Category 6™

QuikSCAT's Replacement, the RapidScat Ocean Wind Sensor, Installed on Space Station

By: JeffMasters, 3:17 PM GMT on September 30, 2014

In November 2009, one of the greatest success stories in the history of satellite meteorology came to an end when the venerable QuikSCAT satellite failed. Launched in 1999, the QuikSCAT satellite became one of the most useful and controversial meteorological satellites ever to orbit the Earth. It carried a scatterometer--a radar instrument that can measure near-surface wind speed and direction over the ocean. Forecasters world-wide came to rely on QuikSCAT wind data to issue timely warnings and make accurate forecasts of tropical and extratropical storms, wave heights, sea ice, aviation weather, iceberg movement, coral bleaching events, and El Niño. Originally expected to last just 2 - 3 years, QuikSCAT made it past ten, a testament to the skill of the engineers that designed the satellite. A QuikSCAT replacement called ISS-RapidScat was funded in 2012 and built in just 18 months. RapidScat was successfully launched on September 20, 2014 on a SpaceX Dragon cargo spacecraft, which docked last week with the International Space Station (ISS.) This morning, RapidScat was plucked out of the Dragon and install it on the Space Station. The heaters have been turned on, and full activation of RapidScat is expected on Wednesday. In a clever reuse of hardware originally built to test parts of NASA's QuikScat satellite, RapidScat cost NASA just $30 million--80% lower than if the instrument had been built new.


Figure 1. Members of the Robotics Flight Control team at NASA and CSA (Canadian Space Agency) sent commands from their ground control center to the ISS to move the robots Canadarm2 and Dextre to install RapidScat on the Space Station on Tuesday, September 30, 2014. The white cylinder is the SpaceX Dragon, docked at the ISS. Thanks go to NASA/CSA's Kamran Bahrami for correcting me on where the commands to install RapidScat originated from. Image credit: Alexander Gerst.

What RapidScat will do
ISS-RapidScat is a radar scatterometer designed to sense near-surface winds over the ocean. The instrument sends a pulse of 13.4 gigahertz microwaves towards the Earth’s surface and measures the intensity of the return pulse that reflects back from the surface. In general, strong radar return signals represent rough surfaces, while weak radar return signals represent smooth surfaces. Stronger winds produce larger waves and therefore stronger radar return signals. The return signal also tells scientists the direction of the wind, since waves line up in the same direction the wind is blowing. The ISS orbit takes the space station between 51.6°N - 51.6°S latitude, and RapidScat will not be able to "see" ocean winds at high latitudes beyond 57°. QuikSCAT measured winds in a swath 1,800 km wide centered on the satellite ground track, but RapidScat's swath will be only 900 km wide, since it is orbiting at a lower altitude (375 - 435 km high versus 800 km for QuikSCAT.) The instrument will be able to "see" with a resolution of up to 12.5 km (7.8 miles.) It completes 15.51 orbits per day, and revisits the same part of the ocean beneath it once every two days. This compares with QuikSCAT, which covered 93% of Earth's surface in 24 hours. The advertised accuracy of RapidScat winds: for wind speeds 7 to 45 miles per hour (3 to 20 meters per second), an accuracy of about 4.5 miles per hour (2 meters per second); for wind speeds of 45 to 70 miles per hour (20 to 30 meters per second), an accuracy within 10 percent; for wind direction, an accuracy of 20 degrees. Precipitation generally degrades the wind measurement accuracy, and accuracy is also reduced at the edge of the swath. Useful data from RapidScat will likely not be available for several months, to allow time for the scientists to validate and calibrate the data being taken. RapidScat's lifetime will be relatively short--just a two-year mission is planned. Scatterometer data is extremely valuable for many aspects of hurricane forecasting, providing early detection of surface circulations in developing tropical depressions, and helping define gale (34 kts) and storm-force (50 kts) wind radii. The information on wind radii from scatterometers is especially important for tropical storms and hurricanes outside the range of aircraft reconnaissance flights conducted in the Atlantic and Eastern Pacific basins, and for the regions where there are no reconnaissance flights (Central Pacific, Western Pacific, and Indian Ocean). Accurate wind radii are critical to the National Hurricane Center (NHC), Central Pacific Hurricane Center (CPHC), and Guam Weather Forecast Office (WFO) watch and warning process, since they affect the size of tropical storm and hurricane watch and warning areas. Between 2003 and 2006, QuikSCAT data were used at NHC 17% of the time to determine the wind radii, 21% of the time for center fixing, and 62% of the time for storm intensity estimates.


Figure 2. Artist's rendering of NASA's ISS-RapidScat instrument (inset), which was sent to the International Space Station in September, 2014 to measure ocean surface wind speed and direction and help improve weather forecasts, including hurricane monitoring. It was installed on the end of the station's Columbus laboratory on September 30. Image credit: NASA/JPL-Caltech/JSC

Alternatives to RapidScat
There are two alternatives to RapidScat available, but neither are as good. There's the European ASCAT satellite, launched in 2007. ASCAT can measure global wind speed and direction twice per day. However, ASCAT sees two parallel swaths 550 km wide, separated by a 720 km gap, and I find it frustrating to use ASCAT to monitor tropical storms, since the passes miss the center of circulation of a storm of interest more than half the time. On the plus side, ASCAT has the advantage that the data is not adversely affected by rain, unlike RapidScat. The other main alternative, the OSCAT instrument, which was sent into orbit on September 23, 2009, on the ISRO (Indian Space Research Organization) Oceansat-2 satellite, suffered an irrecoverable instrument failure on 20 February 2014.The other option is the Windsat instrument aboard the Coriolis satellite (launched in 2003), which measures wind speed and wind direction using a different technique. Evaluation of these data at NHC and NOAA's Ocean Prediction Center (OPC) shown the winds to be unreliable in and around tropical storms.

Related info
QuikSCAT, 1999 - 2009: R.I.P., my November 24, 2009, blog post.
Giving thanks to the Hurricane Hunters and QuikSCAT scientists, my November 21, 2007 post.
Challenging Bill Proenza's QuikSCAT numbers, my July 4, 2007 blog post.
2007 NOAA QuikSCAT user impact study.


Video 1. ‪RapidScat: NASA's Newest Wind Watcher‬

Quiet in the Atlantic
An area of low pressure (Invest 97L) a few hundred miles north-northwest of Bermuda is under high wind shear and is not likely to develop as it heads north and then north-northeast out to sea. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC gave 97L 2-day and 5-day odds of development near 0%. Elsewhere in the Atlantic, the UKMET model is predicting development of a tropical wave on Sunday in the vicinity of the Cape Verde Islands from a tropical wave predicted to come off the coast of Africa on Saturday morning. The GFS and European models give some lukewarm support to this idea. An upper-level trough of low pressure over the Eastern Atlantic will bring high wind shear to the region early next week, making developing difficult.

Eastern Pacific's Rachel weakening; new tropical disturbance 90E developing
In the Eastern Pacific, Tropical Depresion Rachel has weakened to 35 mph sustained winds, and will move little this week and dissipate without affecting any land areas.

An area of disturbed weather (Invest 90E) was located a few hundred miles south of Acapulco, Mexico on Tuesday morning, and was headed west-northwest near 10 mph. This disturbance has good support from all three of our top tropical cyclone genesis models to develop this week. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC gave 90E 2-day and 5-day odds of development of 50% and 90%, respectively. 90E is a threat to bring heavy rains to the Pacific coast of Mexico throughout the week. So far, though, 90E's heavy rains have remained offshore, as seen on satellite loops.

Tropical Storm Phanfone a potential threat to Japan
In the Western Pacific, Tropical Storm Phanfone passed through the Northern Mariana Islands with 50 mph sustained winds on Tuesday morning, and is expected to intensify into a major typhoon, possibly a super typhoon, late in the week. The 00Z Tuesday runs of the GFS and European models show the storm will recurve to the northeast very close to the coast of Japan this weekend.

Jeff Masters

Hurricane

Invest 97L Spinning Near Bermuda; Phanfone a Potential Threat to Japan

By: JeffMasters, 2:27 PM GMT on September 29, 2014

An area of low pressure (Invest 97L) has formed just west of Bermuda, and is bringing heavy rain showers and gusty winds to the island. At 9:45 am AST Monday, the Bermuda Airport reported a waterspout. Winds have gusted as high as 39 mph on the island this morning, and 0.47" of rain had fallen between midnight at 11 am local time on Monday. Satellite loops and Bermuda radar show that 97L has a pronounced low-level spin, but very little in the way of heavy thunderstorms near the center of circulation. The heaviest thunderstorms were in a band 100 - 150 miles to the northeast of the center, and this structure is characteristic of a subtropical storm, not a tropical storm. With wind shear expected to stay a moderate 15 - 20 knots through Monday night, there is a small window of opportunity for 97L to develop into a subtropical cyclone before wind shear rises to a prohibitive 30 - 45 knots on Tuesday. In their 8 am EDT Monday Tropical Weather Outlook, NHC gave 97L 2-day and 5-day odds of development of 30%.


Figure 1. MODIS satellite image of 97L, taken at approximately 1 pm EDT Monday September 29, 2014. Image credit: NASA.

Eastern Pacific's Rachel no threat
In the Eastern Pacific, Hurricane Rachel peaked as a Category 1 storm with 85 mph winds on Sunday morning off the Pacific coast of Baja Mexico, and is now on a weakening trend due to steadily increasing wind shear. Rachel will move little this week and dissipate without affecting any land areas. Rachel's formation gives the Eastern Pacific east of 140°W 17 named storms, 12 hurricanes, and 7 intense hurricanes so far this year. An average Eastern Pacific hurricane season sees 15 named storms, 8 hurricanes, and 3 intense hurricanes during the entire year, with three of those named storms and one hurricane occurring after September 25.

Another area of disturbed weather (Invest 90E) was located near the coast of southern Mexico on Monday morning, and was headed slowly west-northwest to northwest. This disturbance has good support from all three of our top tropical cyclone genesis models to develop late this week. In their 8 am EDT Monday Tropical Weather Outlook, NHC gave 90E 2-day and 5-day odds of development of 20% and 70%, respectively. 90E is a threat to bring heavy rains to the Pacific coast of Mexico throughout the week.


Figure 2. MODIS satellite image of Hurricane Rachel, taken at approximately 6 pm EDT Sunday September 28, 2014. At the time, Rachel was a Category 1 storm with top sustained winds of 75 mph. Image credit: NASA.

Tropical Storm Phanfone a potential threat to Japan
In the Western Pacific, Tropical Storm Phanfone is steadily intensifying as it heads west-northwest at 13 mph towards the Northern Mariana Islands. Phanfone is expected to be near Category 1 typhoon strength when is passes about 250 miles north of Guam near 18 UTC on Tuesday. The storm is expected to intensify into a major typhoon, possibly a super typhoon, late in the week, and the 00Z Monday run of the GFS model shows the storm coming very close to the coast of Japan this weekend.

Hurricane expert Steve Gregory has a more detailed look at 97L in his Monday afternoon post.

Jeff Masters

Hurricane

Tropical Atlantic Uneventful / Tropical Storm Rachel No Threat

By: JeffMasters, 3:18 PM GMT on September 27, 2014

(By Steve Gregory - Substituting for Dr. Masters who is on Vacation.)

Atlantic Basin Hostile to Tropical Cyclone Formation

The weak disturbance that was INVEST 96L is no longer of any significance as it became overwhelmed by both drier and stable air along with increased wind shear. What’s left of the disturbance has turned N/NE.

Although there are 3 other tropical Waves in the Atlantic basin – none pose any threat of development – and no cyclone formations are expected or forecast by the more reliable models for the next 7 days.

TROPICAL STORM RACHEL COULD BRING RAINS TO BAJA

In the East Pacific, Tropical Storm RACHEL is located near 19°N/116°W or some 725NM SW of the southern tip of Baja. The storm intensified some yesterday, with sustained winds now around 55Kts, with some models – along with NHC – now forecasting the system to intensify to just under Hurricane intensity within 12-24 hrs before it begins to weaken rapidly after 48 hrs. Based on my analysis of SAT imagery and trends – it appears a bit unlikely RACHEL will intensify significantly - but regardless, the longer range period will see Rachel weaken rapidly as it moves slowly N/NW or even N/NE at 7Kts into increasingly drier, stable air with increased wind shear.

The GFS has backed off a bit on tracking the remnants of RACHEL to Baja – but whether it spins down to a mere swirl near Baja, or to one just North or west of its current location – the storm will have no impact at all on land.



CLICK IMAGE to open full size image in new window

Fig 1: This mornings overview of the Tropical Atlantic (and East Pacific) shows the remnants of INVEST 96L in the mid Atlantic – actually to the northeast of yesterdays location. An active Tropical Wave from along the western shore of the Yucatan southward into the Pacific is westbound at 10Kts, while a second wave in the east central Caribbean is also westbound at about 10Kts. The only other definable wave is off the west coast of Africa and is drifting westward. None of these Atlantic waves have any chance of developing either due to a very unfavorable upper air wind environment – or dry and stable air. Unlike yesterday when no waves were discernable over Africa, today, a Wave appears to have developed in central Africa within the ITCZ / Monsoonal TROF, and is westbound at 10Kts. This wave is not forecast to develop either.




Fig 2: The color enhanced IR (Infra-Red) image of Rachel shows a small but strong area of convection near the center of the storm, but a somewhat less organized appearance compared to yesterday - with another area of deep convection to the east of the storm center. It appears that there’s been some stable air intrusion from the south, but the environment surrounding the storm remains quite moist, and a weak ‘feeder band’ appears well to the south/southeast.




Fig 3: An early morning 89Ghz microwave pass highlights both the structure of the storm and the exact center. There appears to be a partial eye wall structure and a highly symmetrical spiral band structure – though the only deep convection is found in the eastern semi-circle.



Fig 4: The satellite derived high level wind flow shows a weak, but highly symmetrical outflow atop the storm center, though based on current imagery, and the magnitude of the outflow – intensification to near hurricane force seems unlikely to this observer. A light southeasterly wind shear well under 10Kts doesl, however, support some further deepening over the next 12 hours.




Fig 5: The mean steering current analysis from UW CIMSS for the EPAC show RACHEL in a very light, and variable wind flow area. The storm is still moving NNW, but a deep layered TROF over the West Coast may soon induce a south/southwest flow which would cause RACHEL to turn Northward for awhile until the western US TROF moves east by tomorrow. Most models then show the large High pressure ridge centered northeast of Hawaii building back eastward – turning RACHEL back to the WNW and then West by Monday as the storm rapidly dissipates, and is steered within the general low level trade wind flow.



Fig 6: The official NAVY Forecast track/intensity chart for Rachel (which normally utilizes the NHC forecast in this part of the world) follows the model consensus, and disregards the implied track provided by the GFS.

Jeff will be back on Monday.

Steve

Hurricane

Atlantic Disturbance 96L and Tropical Storm Rachel

By: JeffMasters, 5:19 PM GMT on September 26, 2014

(By Steve Gregory - Substituting for Dr. Masters who is on Vacation.)

INVEST 96L NOT A THREAT

A small area of disturbed weather with periodic bursts of convection near 13°N/42°W remains disorganized as it continues to drift WNW at around 5Kts. Although wind shear remain moderate near 15Kts, there are indications of some outflow at high levels – the system remains surrounded by relatively dry and somewhat stable air which is inhibiting development. None of the global or dynamical specialized hurricane models are forecasting development, while the typically overdone statistically based intensity models are forecasting a slight intensification over the next 5 days. Assuming the system even survives at all, it’s likely to move WNW and then NW before getting absorbed by an approaching upper level TROF.

There are only a couple other Tropical waves across the Tropical Atlantic basin and they’re embedded in generally hostile environments. Meanwhile, I can no longer identify any upstream tropical waves over Africa – a sure sign that the ‘Cape Verdes’ Hurricane Season is rapidly winding down – with the Caribbean region likely to be only area where a cyclone that could threaten the US may yet develop during the remainder of the Fall season.

TROPICAL STORM RACHEL COULD BRING RAINS TO BAJA

Tropical Storm Rachel is located about 450NM SW of the southern tip of Baja, moving WNW at 14Kts. Though NHC is carrying this system as a relatively weak storm with sustained winds near 45Kts, there has been a strong increase in deep convection closer to the low level storm center over the past few hours, and it’s possible winds have increased to near 55Kts – though there has not been a recent Microwave or ASCAT satellite pass to confirm this. Regardless of any intensity change in the short term, the storm is heading towards cooler SST’s and will begin to slowly weaken during the next 72 hrs.

The longer term track of RACHEL is somewhat problematic beyond 72 hours. The western end of a mid-level high pressure ridge over Mexico is expected to weaken during the next few days as a major, deep-layered TROF in the Northeast Pacific digs southeastward towards the western US. The GFS, which is often quite good at track forecasts, calls for Rachel to turn northward this weekend and then head Northeast towards central Baja around the periphery of the high pressure ridge to its east. IF this occurs, the only significant threat would be for locally heavy rainfall, with a low but real chance that high level moisture would eventually stream northeastward across northern Mexico towards the Rockies ahead of the mid-latitude TROF now heading for the western US that will, by next week, be moving eastward across the Rockies. However, depending on how quickly RACHEL spins down to depression or even remnant Low, the much shallower system would most likely never take the turn to the Northeast, but would simply continue on a WNW or NW track as a dissipating remnant swirl.



CLICK IMAGE to open full size image in new window

Fig 1: This mornings overview of the Tropical Atlantic (and East Pacific) shows INVEST 96L essentially in the same area as yesterday about 1,100NM east of the Caribbean, along with Tropical Storm RACHEL well to the southwest of Baja. A Tropical Wave from near western Cuba extends S/SW across the Yucatan and out over the Pacific. This wave is westbound at 18Kts, but lies within an unfavorable area for development. The tropical wave in the far eastern Caribbean is westbound at 14Kts, within an area of deep tropical moisture, but an extremely hostile wind environment. The only other significant tropical wave remains nearly stationary along the west coast of Africa – and is showing signs of being absorbed into the Intertropical Convergence Zone (ITCZ). For the first time since the start of Hurricane Season – no tropical waves are observed over Africa as the ITCZ / African Monsoonal TROF has shifted southward towards the equatorial region, and is also weakening. It would be somewhat surprising to see any strong tropical waves come off the African coast during the remainder of the season.




CLICK BOTTOM IMAGE to open full size image in new window

Fig 2: The (Bottom) image frame of the 72 hour Total Precipitable Water (TPW) ‘Loop’ (top) helps to identify Tropical Waves across the Atlantic. The darker the orange shading – the greater the depth and total volume of moisture derived from satellite imagery. The Loop imagery itself also helps to determine any ‘rotation’ that may be associated with the tropical waves. The more ‘specialized’ last image frame from the loop (Bottom) also includes component wind vector information to show actual areas and magnitudes of ‘rotation. INVEST 96L has become a somewhat ‘lone’ area of deep moisture in mid-Atlantic – and while watching the 72-hour loop, you can see the original large area of deep moisture that had been in this region a few days ago shifted westward to where the TW in the eastern CARIB is now. At the same time, the deep moisture that was orientated east-west as part of the ITCZ ‘bubbled’ northward, and then ‘pinched off’ into the small disturbance 96L. Over the past 24 hours, dry air appears to be infiltrating the deep moisture field associated with 96L.




Fig 3: A closer look at the mostly satellite derived low level winds (with a few surface OBS as well) surrounding 96L show a sharp inverted TROF structure, but little to no clear evidence of an actual low level circulation.




Fig 4: Upper air winds (above 25,000 Ft) is overlaid with the wind shear analysis from the UW CIMSS group, and shows moderate SW wind shear averaging about 15Kts across 96L. There is, however, some outflow wind vectors near some of the heavier convection – but overall, as the system moves WNW over the next few days – it will eventually encounter strong wind shear – and development of this system is extremely unlikely.




Fig 5: The larger overview of the western Atlantic region clearly hints at a rapid shift towards he cool season with a very deep and long wave upper air TROF from the northern Atlantic southwestward to a strong upper Low now over Puerto Rico and continuing into the southern CARIB. A high amplitude ridge extends from near the Yucatan northeastward to just off the east coast. Overall, we find a chaotic and highly energetic but hostile wind pattern across the GOM eastward to the central Atlantic.




Fig 6: The early morning color enhanced IR (Infra-Red) image of Tropical Storm Rachel continues to show very deep convection, with cloud top temperatures near -60°C (indicative of tops near 45,000’).




Fig 7: A closer look at the high level winds near RACHEL shows a very well developed, though not especially strong, anti-cyclonic (clockwise) outflow wind pattern atop the storm. But as the system moves further to the WNW, cooler SST’s and an increasing drier environment surrounding the storm will lead to a slow but steady weakening.




Fig 8: Steering level winds show Rachel still in a E/SE wind flow, but approaching a break in the ridge centered over Mexico and another strong high pressure center well north of Hawaii. The ‘break’ in the ridge is due a relatively deep-layered TROF approaching the west coast. If the storm maintains it strength long enough (as the GFS is calling for) it will eventually be caught up in the southwesterly wind flow around the western periphery of the High over Mexico, and will head towards Baja – weakening considerably by the time it reaches that area. If the storm weakens sooner than the GFS is forecasting, the shallow system will never turn Northeast – instead simply drifting WNW within the general trade wind environment.

The next Tropical Update will be issued tomorrow.

Steve

Hurricane

96L Little Threat; Arctic Sea Ice Bottoms Out at 6th Lowest Extent on Record

By: JeffMasters, 1:04 PM GMT on September 25, 2014

In the Atlantic, a small area of low pressure (Invest 96L) formed Wednesday evening in the middle Atlantic Ocean near 15°N 45°W, about halfway between the Lesser Antilles Islands and the Cape Verde Islands. Satellite loops show that 96L has a pronounced low-level spin, but only a small amount of heavy thunderstorms. Water vapor satellite loops show 96L is surrounded on all sides by large amounts of dry air. With wind shear expected to stay moderate for the next five days, this dry air is likely to keep 96L from developing. None of the reliable tropical cyclone genesis models predict that 96L will develop, and In their 8 am EDT Thursday Tropical Weather Outlook, NHC gave 96L 2-day and 5-day odds of development of 10%. The storm should move slowly northwest during the remainder of the week.


Figure 1. Latest satellite image of 96L.

Two new tropical cyclones in the Pacific
Two new tropical cyclones formed in the Pacific on Wednesday. In the Eastern Pacific, Tropical Storm Rachel formed a few hundred miles southwest of Manzanillo, Mexico. Our reliable computer models keep Rachel well offshore of the coast of Mexico, and this storm is unlikely to be a threat to any land areas. Rachel's formation gives the Eastern Pacific east of 140°W 17 named storms, 11 hurricanes, and 7 intense hurricanes so far this year. An average Eastern Pacific hurricane season sees just 15 named storms, 8 hurricanes, and 3 intense hurricanes during the entire year, with three of those named storms and one hurricane occurring after September 25.

In the Western Pacific, Tropical Depression Kammuri is expected to intensify into a Category 1 typhoon this weekend, but recurve out to sea well offshore from Japan.


Figure 2. Arctic sea ice age (in years) in August during 2004, 2012, and 2014. Comparing 2004 (left) to the all-time record low year of 2012 shows a huge loss of old, thick ice. Old ice is much more difficult to melt off compared to thin first-year ice, which can completely melt out during unusually warm and sunny summers. Old, thick ice has recovered some during 2013 and again in 2014, though there has not been much change in the ice aged 3 or more years. Image credit: University of Colorado.

Arctic sea ice falls to 6th lowest yearly extent on record
Arctic sea ice extent bottomed out at the 6th lowest extent in the 36-year satellite record on September 17 and is now growing, said the National Snow and Ice Data Center (NSIDC) this week. Some of the 2nd-year ice that survived the summer of 2013 has also survived the summer of 2014, so the ice pack is armoring itself a bit going into 2015 with more multi-year ice than usual. This does not mean the Arctic sea ice is on its way to recovery, unfortunately, as Steve Gregory explains in his detailed look at this year's Arctic sea ice minimum in his Wednesday afternoon post.

Jeff Masters

Hurricane Sea Ice

Largest-Ever Meeting of World Leaders on Climate Change Concludes

By: JeffMasters, 2:55 PM GMT on September 24, 2014

Yesterday's Climate Summit 2014 in New York City brought together the largest-ever meeting of world leaders on climate change, with more than 125 world leaders and top government officials in attendance. The meeting, called together by UN Secretary-General Ban Ki-moon with the theme of "Catalyzing Action", sought to challenge leaders to announce bold actions to significantly reduce CO2 emissions, strengthen climate resilience, and mobilize political will for a meaningful legal agreement to be negotiated in Paris in December 2015. “We need to take action now to limit global temperature rise,” said the secretary-general, in opening the session. “We need all hands on deck to ride out this storm.” Plenty of bold promises were indeed made at the meeting, giving hope that next year's climate summit will succeed in negotiating a treaty that will slow down the current record-setting rate of rise in global CO2 emissions. I present below a few of the notable actions and promises made at yesterday's summit and in the days leading up to the event.


Figure 1. U.S. President Barack Obama speaks at the United Nations Climate Summit on September 23, 2014 in New York City. (Photo by Andrew Burton/Getty Images)

Obama promises new U.S. efforts
President Obama promised that in early 2015, the U.S. would announce new, ambitious goals for emissions of greenhouse gases for the post-2020 period. He also announced plans to have federal agencies begin factoring climate resilience into international development programs and investments, to help vulnerable nations better prepare for weather-related disasters, and better plan for long-term threats like steadily rising seas. He opened his speech with this: "The climate is changing faster than our efforts to address it. The alarm bells keep ringing. Our citizens keep marching. We cannot pretend we do not hear them. We have to answer the call. We know what we have to do to avoid irreparable harm. We have to cut carbon pollution in our own countries to prevent the worst effects of climate change. We have to adapt to the impacts that, unfortunately, we can no longer avoid. And we have to work together as a global community to tackle this global threat before it is too late." 


Figure 2. Chinese Vice Premier Zhang Gaoli speaks at the United Nations Climate Summit on September 23, 2014 in New York City. (Photo by Andrew Burton/Getty Images)

China promises to slow down emissions
President Xi Jinping chose not to attend the meeting, and sent Zhang Gaoli, his vice premier, to address the UN. Zhang said that China, the world's biggest emitter of carbon dioxide, would slow the rise of its emissions and reach a peak "as soon as possible." Zhang said China will reveal its goals for reducing emissions for the post-2020 period in early 2015, just as the U.S. promised. As analyzed in detail by Mashable's Andrew Freedman, "the mere mention of a peak in China's carbon dioxide emissions was new and ambitious, considering how quickly the Chinese economy has grown in recent years and how fast emissions have risen as well. During the past decade, for example, China saw about 10% per year increases in carbon dioxide emissions, although that slowed in 2013."

New York City to cut CO2 emissions 80% by 2050
On Saturday, New York City Mayor Bill de Blasio unveiled a plan to reduce the city’s emissions of heat-trapping greenhouse gases by 80 percent over the next four decades. Mayor de Blasio called for “urgent, daring action” in his remarks at the summit, and said he expected to cooperate with leaders of other cities and countries.

Rockefeller Foundation announces plans to divest from fossil fuel companies
The heirs to the Rockefeller oil fortune announced on Sunday that the $860 million philanthropic organization would sell all their assets tied to fossil fuel companies. Divestment from fossil fuel investments has increased significantly in recent years, with 656 individuals and 181 institutions, including philanthropies, religious organizations, pension funds and local governments, divesting assets worth more than $50 billion from portfolios, according to Arabella Advisors, an investment consulting firm.

The World Resources Institute has a more detailed analysis of the outcomes from the U.N. Climate Summit, as does carbonbrief.org.

Quiet in the tropics
The tropics are unusually quiet for September, with no tropical cyclones active. In the Atlantic, none of our reliable models for predicting tropical cyclone genesis shows anything developing over the next five days. A tropical wave coming off the coast of Africa on Friday may be something to watch for development late next week in the Caribbean, the GFS model is predicting, but it is too early to assign a probability of such an event occurring. Dry air will interfere with development of this wave as it crosses between the coast of Africa and the Lesser Antilles Islands. In the Eastern Pacific, a well-organized tropical disturbance (99E) a few hundred miles south of Manzanillo, Mexico was given 5-day odds of development of 90% by NHC in their 8 am EDT Wednesday Tropical Weather Outlook. Our reliable computer models keep 99E well offshore of the coast of Mexico this week as the storm heads west-northwest.

Jeff Masters

Climate Change Politics

A Quiet First Day of Fall for the Tropics

By: JeffMasters, 2:01 PM GMT on September 23, 2014

The tropics are unusually quiet for the first full day of fall, with only one tropical cyclone active--Tropical Depression Fung-Wong in the Western Pacific, which grazed the coast of China near Shanghai Tuesday morning, bringing torrential rains to the coast. Fung-Wong is headed northeast towards South Korea, and will bring heavy rains there on Tuesday and Wednesday before dissipating.

In the Atlantic, none of our reliable models for predicting tropical cyclone genesis shows anything developing over the next five days. A tropical wave coming off the coast of Africa on Friday may be something to watch for development next week, according to the GFS model, but it is too early to assign any probabilities of such an event occurring.

In the Eastern Pacific, a well-organized tropical disturbance (99E) a few hundred miles south of Acapulco, Mexico was given 5-day odds of development of 90% by NHC in their 8 am EDT Tuesday Tropical Weather Outlook. Our reliable computer models keep 99E well offshore of the coast of Mexico this week as the storm heads west-northwest, parallel to the coast of Mexico.


Figure 1. Tropical Storm Fung-Wong as seen by MODIS at approximately 02 UTC Tuesday September 23, 2014. At the time, Fung-Wong had top winds of 40 mph. Image credit: NASA.

Hurricane expert Steve Gregory has a more detailed look at the tropics and this year's Arctic sea ice minimum in his Tuesday afternoon post.

Jeff Masters

Hurricane

People's Climate March Brings 311,000 to New York City

By: JeffMasters, 3:19 PM GMT on September 22, 2014

The largest demonstration supporting climate change action in world history hit the streets of New York City yesterday, when the People's Climate March brought a crowd of 311,000 participants to Manhattan--more than triple pre-march estimates of 100,000. Hurricane Sandy survivors, labor unions, youth groups, congregations from across the religious spectrum and social justice campaigners marched with UN Secretary General Ban Ki–Moon and New York Mayor Bill de Blasio, along with celebrities like Leonardo DiCaprio, Joseph Gordon–Levitt, Mark Ruffalo, Susan Sarandon, and Sting. "This is the planet where our subsequent generations will live," Ban Ki–Moon told reporters. "There is no 'Plan B,' because we do not have 'Planet B.'" Around the world, hundreds of thousands more joined 2,646 events in 156 countries, in a strong show to world leaders that people world-wide demand serious action on climate change at Tuesday's important climate summit in New York City. That meeting, called together by UN Secretary-General Ban Ki-moon, brings together world leaders from government, finance, business, and civil society to galvanize and catalyze climate action.  The Secretary-General has asked these leaders to bring bold announcements and actions to the Summit intended to significantly reduce CO2 emissions, strengthen climate resilience, and mobilize political will for a meaningful legal agreement to be negotiated in Paris in December 2015.


Figure 1. People protest for greater action against climate change during the People's Climate March on September 21, 2014 in New York City. The march, which calls for drastic political and economic changes to slow global warming, was organized by a coalition of unions, activists, politicians and scientists. (Photo by Andrew Burton/Getty Images)


Figure 2. Climate protesters hold a banner reading ' Let's be the change' on the Republique's square during a demonstration to fight climate change, on September 21, 2014 in Paris. Image credit: FRANCOIS GUILLOT/AFP/Getty Images.


Figure 3. Marchers come down 6th Ave during the People's Climate March on September 21 2014, in New York. Image credit: TIMOTHY A. CLARY/AFP/Getty Images

Quiet in the Atlantic and Eastern Pacific
It's quiet in the Atlantic, where none of our reliable models for predicting tropical cyclone genesis shows anything developing over the next five days.

In the Eastern Pacific, Polo has dissipated. A well-organized tropical disturbance (99E) a few hundred miles south-southeast of Acapulco, Mexico was given 5-day odds of development of 80% by NHC in their 8 am EDT Monday Tropical Weather Outlook. Our reliable computer models keep 99E offshore of the coast of Mexico this week as the storm heads west-northwest to northwest, parallel to the coast of Mexico.

In the Western Pacific, Tropical Storm Fung-Wong made landfall in southern Taiwan Sunday morning with sustained winds near 55 mph, knocking out power to 40,000 customers and killing one person. Taiwan's Central Weather Bureau said one remote observation site in the mountains of southern Taiwan recorded 995 millimeters, or nearly 40 inches, of rain Saturday through late Monday morning local time. Fung-Wong brushed the northern end of the Philippines' Luzon Island on Friday morning with sustained winds of 45 mph, bringing torrential rains that flooded Manila and killed eleven people. The storm is headed north towards a third landfall on Monday evening in Zhejiang Province, China.

Jeff Masters

Climate Change Politics

25th Anniversary of Hurricane Hugo Hitting South Carolina

By: JeffMasters, 3:11 PM GMT on September 21, 2014

On September 21, 1989, Hurricane Hugo began the day as a minimum-strength Category 3 hurricane with 115 mph winds. But as a strong trough of low pressure turned the hurricane to the north and accelerated Hugo to a forward speed of 25 mph, the storm took advantage of low wind shear and warm ocean waters to begin a period of rapid intensification. As darkness fell on the 21st, Hugo had grown to huge Category 4 hurricane with 135 mph winds. Its target: the South Carolina coast near Charleston, at Sullivan's Island. At 11:57 pm on the 21st, Hugo made landfall on Sullivan's Island. It was the strongest hurricane on record to hit South Carolina, and the second strongest hurricane (since reliable records began in 1851) to hit the U.S. East Coast north of Florida. Only Hurricane Hazel of 1954 (Category 4, 140 mph winds) was stronger. With a price tag of $9.7 billion (2010 dollars), Hugo was the most expensive hurricane ever to hit the U.S., until Hurricane Andrew surpassed it in 1992.


Figure 1. AVHRR visible satellite image of Hurricane Hugo taken on September 21, 1989. Hugo had intensified to a formidable Category 4 hurricane with 135 mph winds.

On Isle of Palms, a barrier island adjacent to Sullivan's Island, the mayor and several police officers were sheltering in a 2-story building which lay at an elevation of ten feet. As related in a story published in the St. Petersburg Times, they heard the following bulletin on the radio at 10:30pm the night Hugo made landfall:

"The National Weather Service has issued a storm surge update. It appears that the storm surge will be greater than anticipated. It is now expected to reach a height of 17 to 21 feet."

"Mom didn't raise an idiot," said the one cop with the most sense, and he convinced the others to get off the island. They left the island by driving at 5 mph through horizontal sheets of rain and hurricane-force wind gusts over the Ben Sawyer Bridge, which connected Sullivan's Island to the mainland. As they crossed onto the bridge, they passed over a large bump--the bridge and road bed were at different levels. Not good. While crossing the bridge, they could feel it swaying and straining, and heard the sound of metal, twisting and grinding and breaking. They made it, but only barely--minutes later, the hurricane tore the center span of the bridge from its connection on both ends, leaving it a twisted ruin in the bay.


Figure 2. The Ben Sawyer Bridge connecting Sullivan's Island to Charleston, South Carolina, after Hurricane Hugo. Image credit: NOAA Photo Library.

Hugo's storm surge
In McClellanville, on the coast thirty miles northeast of Charleston, between 500 - 1100 people took refuge at the designated shelter for the region, Lincoln High School. Lincoln High is a one-story school, mostly constructed of cinder block, located on the east side of Highway 17, and was believed to be at an altitude of twenty feet. McClellanville is about 4 - 5 miles inland from the open ocean, but lies on the Intracoastal Waterway, so is vulnerable to high storm surges. Near midnight on the 21st, a storm surge of twenty feet poured into Bulls Bay just south of McClellanville, and funneled into the narrow Intracoastal Waterway. Water started pouring into the high school and rose fairly rapidly. Within minutes, people were wading around up to their waists, the water still rising. In the school cafeteria, many refugees gathered on a stage at one end, putting children up on tables. The elevated stage kept them above water; others floated in the water. Another group was in the band room, which had a much lower ceiling than the cafeteria. They had to stand on desks and push out the ceiling tiles for more breathing room, as the water rose within 1 - 2 feet of the ceiling. Fortunately, Hugo's storm surge peaked at that time, at about 16 - 17 feet (Figure 4), and the people sheltering at Lincoln High were spared.


Figure 3. Estimated storm surge (height above ground) as estimated by NOAA's storm surge model, SLOSH. McClellanville (upper right) received a storm surge estimated at 16 - 17 feet.

According to Dr. Stephen Baig, the retired head of the NHC storm surge unit, the back-story is this: To build Lincoln High School, which lies at an altitude of ten feet, the local school board used the same plans that were drawn up for another school that is west of Highway 17, and that IS at 20 feet elevation. Not only the same plans, the same set of working drawings. Those working drawings showed a surveyed elevation of 20 feet above datum (probably NGVD29). Apparently Lincoln High was constructed either without benefit of elevation survey or the plans were not annotated with its site elevation. When the Red Cross inquired as to its utility as an evacuation site, whoever looked at the plans saw the surveyed elevation at 20 feet. That is what the Red Cross published. That is why the school was a designated shelter. Since that near-tragedy, the Red Cross requires a new elevation survey for every potential storm shelter. I think that at the time this was discovered all the designated shelters also were re-surveyed, just to be sure that no similar Lincoln High problems were waiting to happen.

Only one person died from Hugo's storm surge, a woman who sheltered in her mobile home that got struck by the surge. Her death was one of only ten deaths that have occurred due to storm surge in the U.S. in the 35 years between 1969 - 2005 (after the 100+ storm surge deaths due to Hurricane Camille of 1969, and before the 1000+ storm surge deaths due to Hurricane Katrina). This amazingly low death toll can be attributed to four factors:

1) Greater understanding of the storm surge and better storm surge forecasts issued by the National Hurricane Center, thanks to such tools as the SLOSH storm surge model.

2) The excellent job NWS/NHC/FEMA and state and local Emergency Managers have done educating the public on the potential surge they can expect.

3) The success local government has had making evacuations of low-lying areas work.

4) Luck. The 20+ storm surge deaths on the Bolivar Peninsula in 2008 from Hurricane Ike and the 41 storm surge deaths in New York and New Jersey from Hurricane Sandy show that there are still plenty of stubborn, unlucky, or uneducated people who will die when a significant storm surge hits a low-lying populated coast. To illustrate, I'll present an email sent to me from a resident in the Florida Keys during the Keys evacuation order for Hurricane Ike in 2008: I hate to bother you again, but we live on Marathon in the Florida Keys on the Atlantic side, and my husband says that if we see water coming up from storm surge and have an inch of water in our house, that we can outrun the storm surge in our car. Can you please tell me if there is any way this can possibly be true? P.S., I don't know of anyone who lives down here who is planning on evacuating for Ike. Everyone says they are staying. My response: You are right to be skeptical of your husband's idea. Once the surge begins, it typically rises very quickly. If you wait until the water is an inch high before trying to outrun the surge, the odds are that the surge will rise to over a foot high before you get your car out of the driveway. If the water is a foot high, the typical 10 - 15 mph speed of the storm surge's current has enough force to sweep a car away. The Keys have only one road out, and the storm surge will likely be moving perpendicular to the road, cutting off the only escape route well before the hurricane arrives. One of these days, there are going to be a lot of people who fail to evacuate caught and killed in the Keys by the storm surge from a major hurricane.

Kudos and links
I thank Ken Bass for providing the details on the Lincoln High storm surge near-disaster. Ken has written a very readable book about a fictional Category 4 hurricane hitting New York City.

Hurricanes-blizzards-noreasters.com has a web page with links to tons of Hurricane Hugo stories. Included are links to YouTube videos of a "Rescue 911" episode that interviewed survivors of the Lincoln High storm surge scare. The show also did a re-creation of the event.

Our Historical storm surge page has SLOSH model storm surge animations of Hurricane Hugo's landafall, as well as of 39 other famous hurricanes.

My favorite disaster relief charity, Portlight, recommends this 47-minute video documentary about Women's Stories of Reconstruction after Hurricane Hugo hit McClellanville South Carolina in 1989.

If you've never read my story of flying into Hurricane Hugo, do it. Twenty-five years ago on September 15, 1989, I was the flight director on the first hurricane hunter mission into the hurricane. We intercepted Hurricane Hugo as it approached the Caribbean islands, just before Hugo's destructive rampage through the Caribbean and into South Carolina. The crew of the airplane were the first people to encounter the mighty hurricane--and very nearly became its first victims. The mission remains the most harrowing flight ever conducted by the NOAA hurricane hunters. I served as flight meteorologist on that flight, and feel fortunate indeed to be able to tell the story.

Quiet in the Atlantic and Eastern Pacific
Jumping back to September 21, 2014, it's quiet in the Atlantic, where tropical wave 95L off the coast of Africa remains disorganized. In their 8 am EDT Sunday Tropical Weather Outlook, NHC gave the wave 2-day and 5-day odds of development near 0%. This wave will bring heavy rain showers to the Cape Verdes Islands on Sunday and Monday.

In the Eastern Pacific, minimal-strength Tropical Storm Polo continues to weaken due to high wind shear as it heads west-northwest out to sea. All watches and warnings have been dropped in Mexico for Polo. A weak area of low pressure (99E) a few hundred miles south of the Guatemala/Mexico border was given 5-day odds of development of 40% by NHC in their 8 am EDT Sunday Tropical Weather Outlook. Our reliable computer models do not show 99E being a threat to make landfall during the next five days.

In the Western Pacific, Tropical Storm Fung-Wong made landfall in southern Taiwan Sunday morning with sustained winds near 55 mph, knocking out power to 40,000 customers. Fung-Wong brushed the northern end of the Philippines' Luzon Island on Friday morning with sustained winds of 45 mph, bringing torrential rains that flooded Manila and killed ten people. The storm is headed north towards a third landfall in Mainland China, which is expected to occur Monday evening.

Hurricane expert Steve Gregory has a more detailed look at the tropics in his Sunday afternoon post.

Jeff Masters

Hurricane

African Wave 95L and Mexico's Tropical Storm Polo Little Threat

By: JeffMasters, 3:51 PM GMT on September 20, 2014

Satellite loops show that a tropical wave (Invest 95L) off the coast of Africa, a few hundred miles southeast of the Cape Verde Islands, has a moderate degree of spin and heavy thunderstorm activity. The wave is under light wind shear and over warm waters of 28°C (82°F), conditions that favor development, but the 12Z Saturday forecast from the SHIPS model predicts that shear will rise to the moderate range, ocean temperatures will cool, and the air surrounding the storm will grow drier by Sunday, making development unlikely. Our three reliable tropical cyclone genesis models give little support for 95L becoming a tropical depression, and in their 8 am EDT Saturday Tropical Weather Outlook, NHC gave the wave 2-day and 5-day odds of development of 10%. This wave will bring heavy rain showers to the Cape Verdes Islands on Sunday. 95L does not appears to be a threat to any land areas besides the Cape Verde Islands.


Figure 1. MODIS true-color image of Invest 95L off the coast of Africa, at approximately 8 am EDT September 20, 2014. Image credit: NASA.

Tropical Storm Polo weakening, little threat to Mexico
Tropical Storm Polo is steadily weakening due to high wind shear as it heads northwest parallel to coast of Mexico. With cooler waters ahead of it and continued high wind shear likely, Polo does not appear to be a significant threat to bring heavy rains or high winds to hurricane-ravaged Baja, Mexico. The 11 am EDT Saturday Wind Probability Forecast from NHC gave Cabo San Lucas on the southern tip of the Baja Peninsula just an 8% chance of experiencing tropical storm-force winds from Polo. Satellite loops show the classic appearance of a tropical storm experiencing high wind shear, with the low level center exposed to view and all the heavy thunderstorms limited to one side.


Figure 2. Lastest satellite image of Polo.

Tropical Storm Fung-Wong approaching Taiwan
In the Western Pacific, Tropical Storm Fung-Wong is expected to make landfall in southern Taiwan Sunday morning with sustained winds near 55 mph. Fung-Wong brushed the northern end of the Philippines' Luzon Island on Friday morning with sustained winds of 45 mph, bringing torrential rains that flooded the capital of the Philippines, Manila. The resulting flooding killed five people and shut down the city.


Figure 3. Rescuers use a rubber dinghy to rescue trapped residents after heavy monsoon rains spawned by Tropical Storm Fung-Wong flooded Marikina city, east of Manila, Philippines and most parts of the metropolis Friday, Sept. 19, 2014. Heavy rains due to a storm and the seasonal monsoon caused widespread flooding Friday in the Philippine capital and nearby provinces, shutting down schools and government offices. Local authorities reported thousands were evacuated early Friday from severely inundated communities, some under rapid-flowing flood waters more than neck high. (AP Photo/Bullit Marquez)

Jeff Masters

Hurricane

Edouard Dying; Fung-Wong Floods Manila

By: JeffMasters, 2:33 PM GMT on September 19, 2014

The Atlantic's strongest and longest-lived named storm of 2014, Edouard, is near the end of its life. Passage over waters cooler than 23°C (73°F) have resulted in the loss of all of Edouard's heavy thunderstorms, and satellite images show that Edouard is just a swirl of low clouds. Edouard will likely be declared dead by Saturday morning.


Figure 1. Latest satellite image of Edouard.

African tropical wave 95L off the coast of Africa
A tropical wave (Invest 95L) that emerged from the coast of Africa on Wednesday night is being given lukewarm support for development by two of our three reliable tropical cyclone genesis models. Satellite loops show 95L has a moderate degree of spin, but its heavy thunderstorm activity is sparse and disorganized. The wave is under light wind shear and over warm waters of 28°C (82°F), conditions that favor development. In their 8 am EDT Friday Tropical Weather Outlook, NHC gave the wave 2-day and 5-day odds of development of 20% and 30%, respectively. This wave is expected to move northwest near or over the Cape Verdes Islands by Sunday. Once it is northwest of the islands early next week, 95L will encounter drier air, making further development difficult. If 95L does develop, I doubt it would affect any land areas besides the Cape Verde Islands.


Figure 2. MODIS true-color image of Invest 95L off the coast of Africa, at approximately 8 am EDT September 19, 2014. Image credit: NASA.

Odile's rains flooding New Mexico and Texas
Moisture left over from Hurricane Odile continues to slosh over the Southwest U.S., where widespread areas of 2 - 4" of rain have fallen. The heaviest rains were over Southeast New Mexico near the Texas border, where a few areas of 6" fell in a 12-hour period ending Friday morning, causing flooded roads and a number of high-water rescues. Additional rains of 1 - 3" are possible in this area through Saturday morning.


Figure 3. Observed precipitation for the 4-day period ending Friday, September 19, 2014. The remnants of Hurricane Odile dumped a large area of 2 - 4 " of rain over the Southwest U.S. Image credit: National Weather Service.

Tropical Storm Polo brushing Southwest Mexico
Sporadic heavy rains continue to fall along the Pacific coast of Southwest Mexico as Tropical Storm Polo heads to the northwest, parallel to shore. The models are in good agreement that the core of Polo will stay offshore of both Southwest Mexico and the Baja Peninsula, but Polo's heavy rains of 2 - 4" along the coast of Southwest Mexico still represent a flooding threat. The 5 am EDT Friday Wind Probability Forecast from NHC gave Cabo San Lucas on the southern tip of the Baja Peninsula a 25% chance of experiencing tropical storm-force winds from Polo, and a 0% chance of hurricane-force winds. Satellite loops show that Polo is experiencing wind shear that is keeping heavy thunderstorms from developing on its northeast flank.


Figure 4. Tropical Storm Polo as seen by MODIS at 4:35 pm EDT Thursday September 18, 2014. At the time, Polo had top winds of 70 mph. Wind shear was keeping heavy thunderstorms from developing on its northeast flank. Image credit: NASA.

Tropical Storm Fung-Wong floods Manila
In the Western Pacific, Tropical Storm Fung-Wong brushed the northern end of the Philippines' Luzon Island on Friday morning with sustained winds of 45 mph. Monsoon rains intensified by Fung-Wong dumped 10.6" (268 mm) of rain overnight on the capital of the Philippines, Manila, causing widespread flooding that killed one person and shut down the city. Fung-wong has grown disorganized by its passage over Luzon, and is not expected to become a typhoon when it heads north and affects China this weekend.


Figure 5. Residents are rescued by police and rescue volunteers after continued monsoon rains enhanced by tropical storm Fung-Wong inundated parts of Marikina on September 19, 2014 in Manila, Philippines. Thousands were forcibly evacuated from their homes after heavy rains caused flooding in major parts of the metropolis, shutting down schools and government offices. (Photo by Dondi Tawatao/Getty Images)

Jeff Masters

Hurricane

Earth Has its Warmest Summer and August on Record

By: JeffMasters, 6:33 PM GMT on September 18, 2014

August 2014 and the June - August Northern Hemisphere summer period of 2014 were Earth's warmest since records began in 1880, said NOAA's National Climatic Data Center (NCDC) today. NASA also rated August 2014 as the warmest August on record. August is the third time NOAA has ranked a 2014 month as the warmest on record; May and June 2014 were the warmest May and June on record (April 2014 was originally ranked as tied for warmest April on record, but has since been revised downwards to the second warmest April on record.) Global ocean temperatures during August 2014 were the warmest on record, and the 0.65°C (1.17°F) ocean temperature anomaly was the highest ever measured, beating the record set just two months previously in June 2014. Global land temperatures in August 2014 were the 2nd warmest on record. The first eight months of 2014 (January–August) were the third warmest such period on record for the globe, with an average temperature 0.68°C (1.22°F) above 20th century average. If 2014 maintains this temperature departure from average for the remainder of the year, it will be the warmest year on record. Global satellite-measured temperatures in August 2014 for the lowest 8 km of the atmosphere were the 14th or 8th warmest in the 36-year record, according to Remote Sensing Systems and the University of Alabama Huntsville (UAH), respectively. Wunderground's weather historian Christopher C. Burt details the notable global extreme weather events of August 2014 in his latest post.


Figure 1. Departure of temperature from average for August 2014, the warmest August for the globe since record keeping began in 1880. Record-warm conditions were experienced over portions of six continents, and a small area of record cold was observed over Northern Russia. Overall, 26 countries across every continent except Antarctica had at least one station reporting a record high temperature for August. The United States and the Russian Federation each had stations that reported record warm temperatures as well as at least one station with a record cold temperature for the month. Image credit: National Climatic Data Center (NCDC) .



One billion-dollar weather disaster in August 2014
One billion-dollar weather-related disaster hit the Earth during August 2014--a flood disaster in the U.S. that swamped Detroit, Baltimore, and Long Island, according to the August 2014 Catastrophe Report from insurance broker Aon Benfield. They also classified two new billion-dollar disasters from previous severe weather outbreaks in April and June in the U.S., bringing the global number of billion-dollar weather disasters for the first eight months of 2014 to seventeen. This is well behind the record-setting pace of 2013, which had 28 billion-dollar weather disasters by the end of August, and ended up with a record 41 by the end of the year.


Disaster 1. Flooding near Islip, New York, on August 13, 2014. Islip set an all-time New York state record for 24-hour precipitation with 13.57". Image credit: wunderphotographer Hurricane765.

An El Niño Watch continues
August 2014 featured neutral El Niño conditions in the equatorial Eastern Pacific, and sea surface temperatures were about 0.4°C above average in August in the so-called Niño 3.4 region (5°S - 5°N, 120°W - 170°W), where SSTs must be at least 0.5°C above average for five consecutive months for an El Niño event to be declared. NOAA is continuing its El Niño Watch, but in early August dropped their odds of a fall or winter El Niño from 80% to 60 - 65%.

Arctic sea ice falls to 7th lowest August extent on record
Arctic sea ice extent during August was the 7th lowest in the 36-year satellite record and was similar to August 2013 levels, according to the National Snow and Ice Data Center (NSIDC). As of September 17, the end of this year’s Arctic sea ice melt season was imminent and the minimum extent will be slightly lower than last year’s, making it the sixth lowest extent in the satellite record. The Northern Sea Route (also known as the Northeast Passage)--the shipping lane along the north coast of Russia in Arctic waters--has been open for over a month, according to ice edge analyses by the National Snow and Ice Data Center and the University of Illinois Cryosphere Today. The Northwest Passage through the Arctic waters of Canada did not open, and will stay closed in 2014. Mariners have been attempting to sail these passages since 1497. The Northeast Passage opened to ice-free navigation for the first time in recorded history in 2005, with the Northwest Passage following suit during the summer of 2007. Both passages have been open multiple summers since then, as long-term melting of the ice has continued. However, this summer's weather in the Arctic has featured winds favorable for not letting sea ice drift out through Fram Strait, and we have seen the total volume of sea sea as estimated by the University of Washington PIOMAS model pull back from the record low set in 2012. Some of the 2nd-year ice that survived the summer of 2013 has also survived the summer of 2014, so the ice pack is armoring itself a bit going into 2015 with a modest amount of multi-year ice compared to what we went into 2012 with (2012 set the record for lowest Arctic sea ice extent.)

Most spectacular weather videos of August

Video 1. A Russian man pulls out of his garage just as a tornado arrives. He tries to go back in the garage, but it is destroyed before he can. Note: The dash cam date is incorrect; the tornado occurred on August 29, 2014 in Bashkiria, Russia. According to http://www.extremestorms.com.au/tornado-bashkiria-russia/, the tornado was an EF-3 that killed two people and injured 80.


Video 2. This videographer got way too close to a landspout-type tornado which occurred under a non-supercell thunderstorm on August 31, 2014. The tornado had a diameter of about 100 feet, and the photographer was less than 50 feet from the storm. Seriously, take shelter, dude! According to Michael Thuesner of climahaus.com, the video was taken in Butjadingen, Germany, looking NW/N across a small artificial lake. Here is a second video taken from a safe distance.


Video 3. This videographer was also too close to an August 6, 2014 tornado i‪n San Cristóbal de Las Casas, Chiapas, México‬.

Win $100 in this month's wunderground "Climate Lottery"
Every three months, the Weather Channel's Guy Walton runs a "Climate Lottery" in his wunderground blog where players guess U.S. temperatures for the coming three months. This summer's winner earned a cool $100. The lottery for this fall is now open; to participate, simply go to Guy's blog and pick three numbers between 1 and 120 (with 1 representing the coldest possible ranking and 120 being the highest possible ranking) for September, October, and November 2014 U.S. temperatures, plus a tie-breaker “Power Ball” or overall ranking number for fall 2014. Post your prediction in the comments section of the blog. Picks must be made by midnight EDT October 5th. The National Climatic Data Center’s ranking numbers for fall 2014 will be posted on or shortly after December 15th, 2014.

Jeff Masters

Climate Summaries

Odile's Remnants Drench Southwest U.S.; Polo Expected to Stay Offshore of Mexico

By: JeffMasters, 3:16 PM GMT on September 18, 2014

Tropical Storm Odile is no more, destroyed by the rough terrain of Mexico and separation from warm ocean waters, after making landfall in the Northern Gulf of California 110 miles south of the Arizona border early Wednesday afternoon. The moisture from Odile lives on over the Southwest U.S., though, and has brought heavy rains of 2 - 4" over portions of Southeast Arizona, Southern New Mexico, and extreme Western Texas as of Thursday morning. Lubbock, Texas was under an areal flood warning Thursday morning, due to rains of 3 - 5", with some thunderstorms dropping rain at a rate of 5" per hour. Additional heavy rains of 3 - 6" will affect Eastern New Mexico and Western Texas over the next two days, as the core of Odile's remnants push eastwards. A flash flood watch is posted for El Paso in Texas, and Las Cruces and Roswell in New Mexico. During the past day, atmospheric moisture levels have been near or above the highest values on record for so late in the year over much of the region (with records going back to 1947.)


Figure 1. Predicted precipitation for the 7-day period ending Thursday, September 25, 2014, from NOAA's Weather Prediction Center. A large area of 3 - 6 " of rain (orange colors) is expected over Eastern New Mexico and Western Texas.

Hurricane Polo brushing Southwest Mexico
Heavy rains are falling along the Pacific coast of Southwest Mexico as Hurricane Polo heads to the northwest, parallel to shore. The models have come into increasing agreement that the core of Polo will stay offshore of both Southwest Mexico and the Baja Peninsula, but Polo's heavy rains of 5 - 10" along the coast of Southwest Mexico represent a serious flooding threat. The 11 am EDT Thursday WInd Probability Forecast from NHC gave Cabo San Lucas on the southern tip of the Baja Peninsula a 30% chance of experiencing tropical storm-force winds from Polo, and a 1% chance of hurricane-force winds. Satellite loops show that Polo has plenty of heavy thunderstorms, but no eye yet. A hurricane hunter aircraft will investigate Polo Thursday afternoon.


Figure 2. Latest satellite image of Polo.

Edouard still a Category 1 hurricane, but weakening
Hurricane Edouard, the Atlantic's first major hurricane of the past two years, was still a Category 1 storm on Thursday morning, but had begun weakening due to passage over waters cooler than 24°C (75°F). Satellite images show that Edouard has lost its eye and much of its heavy thunderstorms, and is moving very rapidly to the east. Edouard is expected to dissipate without ever hitting any land areas.


Figure 3.The view from NOAA hurricane hunter research aircraft N42RF as it orbited inside the eye of Hurricane Edouard when it was a Category 3 storm with 115 mph winds on September 16, 2014. While in the eye, N42RF launched a drone "coyote" aircraft to take measurements at low altitude in the hurricane, where humans fear to go. Image credit: Kristie Twining, NOAA Hurricane Research Division. See the NOAA Hurricane Research Division blog for more details on this year's research missions.


Figure 4. Hurricane Edouard as seen from the International Space Station at approximately 10:30 am EDT Wednesday September 17, 2014. At the time, Edouard was a Category 1 storm with top sustained winds of 90 mph. Image credit: Reid Wiseman.

New African tropical wave 95L off the coast of Africa
A tropical wave (Invest 95L) that emerged from the coast of Africa on Wednesday night is being given support for developing by two of our three reliable tropical cyclone genesis models. Satellite loops show 95L has a moderate degree of spin, but sparse heavy thunderstorm activity. The wave is under light wind shear and over warm waters of 28°C (82°F), conditions that favor development. In their 8 am EDT Thursday Tropical Weather Outlook, NHC gave the wave 2-day and 5-day odds of development of 10% and 20%, respectively. This wave is expected to move northwest near or over the Cape Verdes Islands over the weekend. Once it is northwest of the islands early next week, 95L will encounter drier air and increased wind shear--conditions hostile for development.

Tropical Storm Fung-wong forms near the Philippines
In the Western Pacific, Tropical Storm Fung-wong spun up in the waters a few hundred miles east of the Philippines on Wednesday, and is expected to intensify into a Category 1 typhoon and brush the northern end of the Philippines' Luzon Island on Friday. Fung-wong may be a threat to Japan early next week.

The iCyclone Facebook page has some frightening video of Odile's landfall in Cabo San Lucas, showing the inside of storm chaser Josh Morgerman's hotel taking heavy damage.

August 2014 was Earth's warmest August on record said NOAA today, and I'll have a new post with the details this afternoon.

Jeff Masters

Hurricane

Odile Nearing the Arizona Border; Polo Nearly a Hurricane; Edouard Weakens to Cat 1

By: JeffMasters, 3:27 PM GMT on September 17, 2014

Tropical Storm Odile is being pulled apart by wind shear as it tracks northeast at 6 mph across the northern Gulf of California. At 11 am EDT Wednesday, Odile was still a minimal 40 mph tropical storm, and had advanced within 110 miles of the Arizona border. According to NOAA's Historical Hurricane Tracks website, only two other named storms since 1949 are recorded to have maintained tropical storm strength in the Gulf of California so close to Arizona--Nora of 1997, and Katrina of 1967. Both were still hurricanes when they made landfall at the northern end of the Gulf of California. Two other named storms, Raymond (1989) and Lester (1992), made landfall in the Gulf of California south of where Odile is, but managed to maintain tropical storm strength all the way into Southeastern Arizona (thanks to wunderground member Webberweather53 for pointing this out.) Satellite loops show that the low-level circulation of Odile is still over water, but nearly all of Odile's heavy thunderstorms and a circulation at mid-levels have moved ashore near the Arizona/Mexico border. Odile will likely become a remnant low Wednesday night. Copious moisture from Odile's circulation brought scattered heavy rains to Southeast Arizona and Southwest New Mexico on Tuesday, with 24-hour rainfall amounts of 0.5 - 1.5" common. Heavy rain will ramp up in intensity significantly on Wednesday evening, though, as the core of Odile's remnants cross the Arizona border. Southeast Arizona and Southwest New Mexico are at the at highest risk of flooding, with rainfall amounts of 3 - 6" likely, and up to 9" may fall in the mountains. A flash flood watch is posted for Phoenix and Tucson in Arizona, and for Las Cruces, New Mexico. Odile's heavy rains come just ten days after moisture from Hurricane Norbert drenched Southern Arizona, bringing Phoenix its heaviest single-day rainfall in recorded history. According the the NWS in Tucson, the arrival of moisture from Odile just ten days after Norbert marks the first time on record that moisture from two tropical storms have brought the state heavy rains in a 10-day span.


Figure 1. Predicted precipitation for the 3-day period 8 am EDT Wednesday - 8 am EDT Saturday, from NOAA's Weather Prediction Center. A large area of 3 - 7 " of rain (orange colors) is expected over Southeast Arizona and Southwest New Mexico.

Tropical Storm Polo brushing Southwest Mexico
The Pacific coast of Mexico has a new hurricane threat to be concerned with--Tropical Storm Polo, which had intensified to 60 mph sustained winds 260 miles SSE of Manzanillo, Mexico at 11 am EDT Wednesday. The models have come into increasing agreement that the core of Polo will stay offshore, but the storm is close enough to the coast that a Tropical Storm Warning has been issued for the coast of Southwest Mexico. The 11 am EDT Wednesday WInd Probability Forecast from NHC gave Cabo San Lucas on the southern tip of the Baja Peninsula a 22% chance of experiencing tropical storm-force winds from Polo, and a 1% chance of hurricane-force winds. Those odds were 43% and 1%, respectively, for Manzanillo. Satellite loops show that Polo has plenty of heavy thunderstorms that are steadily growing more organized.


Figure 2. Latest satellite image of Polo.

Edouard weakens to a Category 1 hurricane
After spending just 6 hours at Category 3 strength on Tuesday, Hurricane Edouard, the Atlantic's first major hurricane of the past two years, has steadily weakened to Category 1 status as of Wednesday morning. Edouard is headed northeast over the Central Atlantic, and is not a threat to any land areas. On Thursday, Edouard will encounter colder waters below 26°C (79°F) and wind shear will rise significantly to 30 knots, which should cause rapid weakening, with dissipation likely by Friday night. Satellite images show that Edouard remained well-organized on Wednesday morning with a prominent eye. Edouard was the first Atlantic major hurricane since Hurricane Sandy made landfall over Cuba as a Category 3 storm with 115 mph winds on October 25, 2012.


Figure 3. Hurricane Edouard as seen from the International Space Station at approximately 3 pm EDT Tuesday September 16, 2014. At the time, Edouard was a weakening Category 2 storm with top sustained winds of 100 mph. Image credit: Alexander Gerst.

New African tropical wave emerging from Africa
A tropical wave coming off the coast of Africa on Wednesday night is being given some lukewarm support for developing near the Cape Verde Islands by Saturday from our reliable tropical cyclone genesis models. In their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave the wave 2-day and 5-day odds of development of 0% and 10%, respectively. This wave looks like it will have too much dry air to contend with to become a tropical storm.


Figure 4. MODIS true-color image of a tropical wave moving off the coast of Africa at approximately 8 am EDT September 17, 2014. Image credit: NASA.

Jeff Masters

Hurricane

Odile Dumping Heavy Rains on Southwest U.S.; Edouard Becomes a Major Hurricane

By: JeffMasters, 3:28 PM GMT on September 16, 2014

Residents of Mexico's Baja Peninsula are picking up the pieces after devastating Hurricane Odile smashed ashore at Cabo San Lucas near 12:45 am EDT Monday as a Category 3 storm with 125 mph winds. Odile was the strongest hurricane on record to hit the Baja Peninsula, tied with Hurricane Olivia of 1967. Odile's powerful winds caused heavy damage on the southern tip of Baja, where the tourist meccas of Cabo San Lucas and San Jose del Cabo lie. The airports in both cities are closed, with the San Jose del Cabo airport (7th busiest in Mexico) closed until September 22, and the Cabo San Lucas airport may be closed until October. Fortunately, no deaths are being attributed to the hurricane--a tribute to the excellence of Mexico's civil defense system.


Figure 1. The Cabo San Lucas Airport was heavily damaged by Hurricane Odile, and will remain closed until October. Photo posted to Twitter by Matthew Perry ‏@perrymatt ‪(pic.twitter.com/WK6SJLyJXL)‬.

Odile's heavy rains
NASA's TRMM satellite estimated that Odile produced rainfall rates of 188.4 mm (7.4 inches) per hour one hour before landfall. La Paz reported 6.58" (168.9 mm) in 24 hours ending at 3:45 pm EDT Monday. A Personal Weather Station in Santa Rosa, about 3 miles inland from the coastal city of San Jose del Cabo, measured 27.36" (695 mm) of rain--though this measurement may not be reliable, since it came from a personal weather station. The annual average rainfalll in Cabo San Lucas is just 8.7" (221 mm).


Figure 2. NASA's TRMM satellite passed directly above Hurricane Odile on September 15, 2014 at 0344 UTC, about an hour before the hurricane hit Baja California near Cabo San Lucas. The image above shows rainfall derived from TRMM's Precipitation Radar (PR) and Microwave Imager (TMI) instruments overlaid on a GOES-WEST enhanced Infrared image received at 0330 UTC. TRMM PR showed that Odile contained intense thunderstorms dropping rain at a rate of over 188.4 mm ( about 7.4 inches) per hour in the hurricane's nearly circular eye wall. Image credit: NASA.

Forecast for Odile
Interaction with the rough terrain of the Baja Peninsula knocked Odile down to Category tropical storm with 55 mph winds as of 11 am EDT Tuesday, and the storm will continue to steadily weaken as it heads north across the Gulf of California and makes a second landfall along the northeast coast of the Gulf on Wednesday. Heavy rains will be the main threat from Odile. The storm's circulation is bringing up plenty of moisture from the Tropical Pacific, and the remnant circulation from Odile will combine with this moisture to create flooding rains over Northern Mexico and the Southwest U.S. most of the week. The 06Z Tuesday run of the GFDL model put Eastern Arizona in the highest risk area for heavy precipitation, while the official 7-day precipitation forecast from NOAA shows Southeast Arizona and Southwest New Mexico at highest risk of flooding rains of 4 - 8". A flash flood watch is posted for Phoenix and Tucson in Arizona. An outer spiral band of Odile was over Southeast Arizona on Tuesday morning, and produced a thunderstorm between Tucson and Phoenix whose high winds derailed a train near Picacho.


Figure 3. Predicted rainfall amounts for the 5-day period beginning at 2 am EDT Tuesday September 16, 2014 from Hurricane Odile, from the GFDL hurricane model. A swath from the Mexican coast of the Gulf of California through Eastern Arizona is predicted to get 4 - 8" of rain. Image credit: NOAA/GFDL.

Tropical Storm Polo a threat to Southwest Mexico
The Pacific coast of Mexico has a new heavy rainfall threat to be concerned with--Tropical Storm Polo, which formed about 360 miles SSE of Acapulco at 5 am EDT Tuesday. Polo is expected to head northwest towards the Pacific coast of Mexico on Tuesday and Wednesday, and will be capable of bringing heavy rains of 4 - 8 inches of rain to the coast of Southwest Mexico near Manzanillo Wednesday through Friday. While most of our reliable forecast models show Polo will miss making landfall, the reliable European model has the storm hitting Mexico near Manzanillo on Thursday, while the UKMET model shows Polo coming very close to the tip of the Baja Peninsula on Sunday. The 11 am EDT WInd Probability Forecast from NHC gives Cabo San Lucas on the southern tip of the Baja Peninsula a 31% chance of experiencing tropical storm-force winds from Polo, and a 2% chance of hurricane-force winds. Satellite loops show that Polo has plenty of heavy thunderstorms, but the storm is just beginning to get organized.

A remarkably active 2014 Eastern Pacific hurricane season
Polo's formation brings the 2014 tally for the Eastern Pacific east of 140°W to 16 named storms, 10 hurricanes, and 7 intense hurricanes. An average Eastern Pacific hurricane season sees 15 named storms, 8 hurricanes, and 3 intense hurricanes during the entire year, and we are close to tying the record of eight intense hurricanes in a season set in 1992. What's really remarkable about the 2014 season is the proportion of named storms that have intensified to major hurricane strength: 8 of 15, or more than 50%. That's really difficult to do, particularly when the cold water wakes left behind by previous major hurricanes chill down the sea surface temperatures. Wunderground member wxgeek723 put together this list of other notable hurricane events in the Eastern Pacific in 2014:

-The strongest May hurricane on record: Category 4 Amanda (155 mph winds)
-Persistent Genevieve, which visited three basins and blossomed into a Category 5 monster
-Twin hurricanes Iselle and Julio threatening Hawaii
-Iselle, with 60 mph winds, the strongest named storm on record to hit the Big Island of Hawaii
-Karina, the seventh longest-lived Eastern Pacific storm
-Category 5 Marie (160 mph winds), the sixth strongest Eastern Pacific hurricane on record
-Category 3 Norbert, which put a sliver of California in its TS cone and fed into Phoenix's wettest day in history
-Odile, the strongest hurricane to ever hit Baja and the twelfth strongest Eastern Pacific hurricane on record


Figure 4. MODIS satellite image of Hurricane Edouard, taken at approximately 12 pm EDT Monday September 15, 2014. At the time, Edouard was a Category 2 storm with top sustained winds of 105 mph. Image credit: NASA.

Edouard becomes the Atlantic's first major hurricane
The Atlantic's first major hurricane since Hurricane Sandy of 2012 is Hurricane Edouard, which intensified into a Category 3 storm with 115 mph winds at 11 am EDT Tuesday. Edouard is heading north-northwest at 13 mph over the Central Atlantic, and is not a threat to any land areas. Satellite images show that Edouard remains well-organized with a prominent eye. Edouard is the first Atlantic major hurricane since Hurricane Sandy made landfall over Cuba as a Category 3 storm with 115 mph winds on October 25, 2012.

New African tropical wave may develop this weekend
There is a new tropical wave predicted to come off the coast of Africa on Wednesday that all three of our reliable genesis models are predicting could develop near the Cape Verde Islands by Friday or Saturday. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC gave the wave 2-day and 5-day odds of development of 0% and 20%, respectively.


Figure 5. MODIS satellite image of Typhoon Kalmaegi over China just north of Hainan Island, taken at approximately 12:30 am EDT Tuesday September 16, 2014. At the time, Kalmaegi was a Category 1 storm with top sustained winds of 80 mph. Image credit: NASA.

Typhoon Kalmaegi hits China
In the Western Pacific, Category 1 Typhoon Kalmaegi hit China just north of Hainan Island near 2 am EDT Tuesday as a Category 1 storm with 80 mph winds. The typhoon hit Luzon Island in the Philippines on Sunday, also as a Category 1 storm with 80 mph winds. The typhoon killed ten people in the Philippines, eight of them when a ferry capsized. Kalmaegi is expected to make a third landfall in northern Vietnam as a tropical storm or minimal Category 1 typhoon around 1 pm EDT Tuesday.

Hurricane expert Steve Gregory has a more detailed look at the tropics in his Tuesday afternoon post.

Jeff Masters

Hurricane

Category 3 Odile the Strongest Hurricane on Record to Hit Baja

By: JeffMasters, 2:00 PM GMT on September 15, 2014

Destructive Hurricane Odile powered ashore at Cabo San Lucas on Mexico's Baja Peninsula near 12:45 am EDT Monday as a Category 3 storm with 125 mph winds. Odile was the strongest hurricane on record to hit the Baja Peninsula, tied with Hurricane Olivia of 1967. An Air Force hurricane hunter plane was in Odile Sunday afternoon, and measured a surface pressure of 922 mb. This pressure puts Odile in pretty select company--only two other Eastern Pacific hurricanes have had lower pressures measured in them by the Hurricane Hunters (though a total of eleven Eastern Pacific hurricanes have had lower pressures, if we include satellite-estimated pressures.) The only major hurricane on record to affect Southern Baja was Hurricane Kiko of 1989, which moved ashore on the Gulf of California side of the peninsula just south of La Paz as a Category 3 storm with 120 mph winds.


Figure 1. MODIS satellite image of Hurricane Odile approaching the tip of Mexico's Baja Peninsula, taken at approximately 4:30 pm EDT Sunday September 14, 2014. At the time, Odile was a Category 3 storm with 125 mph winds. Image credit: NASA.


Figure 2. Last radar image of Hurricane Odile taken at 4:46 pm EDT Sunday September 14, 2014, before the radar failed. Image credit: Conagua.

Damage from Odile will be heavy
A Personal Weather Station in Santa Rosa, about 3 miles inland from the coastal city of San Jose del Cabo, recorded winds of 76 mph, gusting to 114 mph, between 11 - 11:30 pm local time Sunday night. The station measured 27.36" of rain, which I believe (and hope!) is erroneous. All other weather stations, including the official airport stations in San Jose del Cabo and Cabo San Lucas, failed before the eye of the storm hit the coast. Storm chaser Josh Morgerman of iCyclone weathered the storm in a hotel in Cabo San Lucas. His reports last night paint a picture of an extremely violent and dangerous hurricane landfall:

9:20 pm. Front doors of hotel blew out of their frames while I was on with The Weather Channel. We've now piled a mountain of furniture against the broken frames. Wind blowing into lobby. Building getting hammered. Screaming, roaring sounds. Whoa. Building just enveloped in raw power.

9:35 pm. We must be in inner eyewall. High-energy blasts of wind smashing building, finishing off doors. Violence. The mountain of furniture can't keep it out. Whoever said outer eyewall had the max winds was wrong-- inner *way* worse.

10 pm. Ears popping. Front entrance completely destroyed. Debris blowing by opening at great speeds. Car alarms going off. Rain and wind enveloping lobby.

10:10 pm. Sounds of trains going by, with whistling. Ears hurt from pressure. Large, thick plate-glass window just exploded-- didn't break, exploded. Interior walls vibrating. One of the worst cyclones I've ever been in. Frightening.

10:35 pm. It's calming. Yes, I think it's calming, praise the Lord. Barometer just dipping down to 949 mb now.

11:05 pm. Calm-- or what feels like calm when you're shell-shocked. Winds maybe 20 knots. Pressure 942.8 mb. People peeking outside, walking around. The front of the hotel looks like it was put through a blender.

11:25 am. Hissing sounds, and a low howl. A piece of tin tumbling across the parking lot. Pressure back up to 952 mb. The eye is passing and we're going back into the cyclone.

Midnight. CODE RED. At 11:46 pm, the backside of the eyewall hit-- no buildup-- just all of a sudden the howling and banging started up again. The hotel manager joked that it sounded like gunshots. Then at maybe midnight... BOOM!!!!! The entire glass wall of the lobby EXPLODED-- with glass, pieces of building, everything flying to the other end of the lobby. Like an explosion in an action movie. A hotel worker and I ducked under the reception counter-- I physically grabbed his head and pushed it under the counter. Glass was everywhere-- my leg gashed-- blood. We crawled into the office-- me, the worker, and the manager-- but the ceiling started to lift up. After five minutes of debate-- breathing hard like three trapped animals-- we made a run for it-- went running like HELL across the lobby-- which is now basically just OUTSIDE-- and made it to the stairwell and an interior hallway. Two nice women dressed my wound. I don't know where my cameradude, Steven, is. I need to find him. People are scared.

1 am. I found Steve-- we were tearfully reunited. I say tearfully because I was so happy to find him alive and OK in the chaos I got emotional. After roaming the flooded, dark hallways alone, I found him sheltered in a bathroom next to the lobby with two other guests. The lobby itself is a heap of wreckage. Steve was in the cloud of flying glass as that wall exploded. Like us, he had to run like hell-- and like me, he was bloodied. Steve saw me and my partners scampering like rats across the lobby earlier-- when we made our escape-- but I didn't hear his calling over the roar of the wind. What you see here is my leg-- dressed in a towel-- Steve's wound dressed in duct tape, and a shoe he fashioned out of duct tape (because he lost his). We're in an interior hall now. We're OK. I think the wind is quieting down. I think. Parts of the hotel are smashed beyond recognition.


Figure 3. The Cabo Villas Beach Cam was still sending images Monday morning after Odile smashed it to the ground. Image credit: Cabo Villas.

Forecast for Odile
Interaction with the rough terrain of the Baja Peninsula knocked Odile down to Category 2 strength with 110 mph winds by 8 am EDT Monday, and the storm will continue to steadily weaken as it moves along the peninsula and its circulation moves over cooler waters. Wind damage will continue to be a major concern through Monday evening, but by Tuesday, heavy rains will be the main concern. Odile's circulation is bringing up plenty of moisture from the Tropical Pacific and from Tropical Depression Sixteen to its southwest, and this moisture will create flooding rains over Northern Mexico and the Southwest U.S. beginning on Tuesday. The 06Z Monday run of the GFDL model put Central Arizona in the highest risk area for heavy precipitation from Odile's moisture.


Figure 4. Predicted rainfall amounts for the 5-day period beginning at 2 am EDT Monday September 15, 2014 from Hurricane Odile, from the GFDL hurricane model. Regions of Mexico along the Gulf of California are expected to receive 8 - 16", while a portion of Central Arizona is predicted to get 4 - 8". Image credit: NOAA/GFDL.

New tropical storm likely to form off the coast of Mexico this week
Our top models for predicting genesis of tropical cyclones are keen on developing a broad area of low pressure (Invest 97E) located about 500 miles south-southeast of Acapulco, Mexico. This system is predicted to follow a northwesterly path parallel to the Pacific coast of Mexico, and might be a danger to Baja early next week--though it is too early to know. In their 8 am EDT Tropical Weather Outlook, NHC gave the disturbance 2-day and 5-day odds of development of 50% and 70%, respectively.


Figure 5. Tracks of all Category 2 and stronger hurricanes to pass within 75 miles of the southern tip of Mexico's Baja Peninsula (light circle) between 1949 - 2013. Only one major hurricane--Hurricane Kiko of 1989--hit Baja during this time span. Data taken from NOAA/CSC's Historical Hurricane Tracks website.

An incredibly active year for major Eastern Pacific hurricanes
Odile's intensification into a Category 4 storm gives the Eastern Pacific east of 140°W seven major hurricanes so far this year. With the season typically only about two-thirds over by September 14, we have a decent chance of tying or beating the record of eight intense hurricanes in a season, set in 1992. The 2014 tally for the Eastern Pacific east of 140°W currently stands at 15 named storms, 10 hurricanes, and 7 intense hurricanes. An average Eastern Pacific hurricane season sees 15 named storms, 8 hurricanes, and 3 intense hurricanes during the entire year. The records for total number of named storms, hurricanes, and intense hurricanes were all set in 1992, with 25 named storms, 14 hurricanes, and 8 intense hurricanes. If we include the Central Pacific between 140°W and 180°W, these record tallies in 1992 were 28 named storms, 16 hurricanes, and 10 intense hurricanes, compared with the 2014 totals of 15 named storms, 11 hurricanes, and 8 intense hurricanes (Genevieve did not become a hurricane and then major hurricane until it crossed from the Eastern Pacific into the Central Pacific.) What's really remarkable about the 2014 season is the proportion of named storms that have intensified to major hurricane strength: 8 of 15, or more than 50%. That's really difficult to do, particularly when the cold water wakes left behind by previous major hurricanes chill down the sea surface temperatures.

Since July, the Eastern Pacific has had ocean temperatures about 0.6°C (1°F) above average and wind shear about 20% below average. The region has been dominated by moist, rising air and low pressure, leading to above average vertical instability. All of these factors are favorable for an active hurricane season. The Atlantic and Eastern Pacific are usually out of phase with their hurricane seasons--when one is active, the other is inactive. This occurs because when the large-scale atmospheric circulation favors rising air and low pressure over one ocean basin, there must be high pressure and dry, sinking air elsewhere to compensate--which typically occurs over the neighboring ocean basin, suppressing hurricane activity there. See my September 11 post for detailed graphics on why the Eastern Pacific has been so favorable for hurricane formation this year.


Figure 6. Latest satellite image of Edouard.

Edouard becomes a Category 2 hurricane; not a threat to land
The strongest hurricane of the 2014 Atlantic hurricane season so far is Hurricane Edouard, which intensified into a Category 2 hurricane with 105 mph winds at 5 am EDT Monday. The previous strongest storm of 2014 was Hurricane Arthur, which topped out at sustained winds of 100 mph as it hit the Outer Banks of North Carolina in early July. Edouard continues chugging to the northwest at 15 mph over the Central Atlantic, and is not a threat to any land areas. Satellite images show that Edouard remains well-organized with a prominent eye. Edouard is likely to become the first major hurricane in two years in the Atlantic by Tuesday.

Quiet in the rest of the Atlantic
There is a new tropical wave predicted to come off the coast of Africa on Thursday that two of our reliable genesis models are predicting could develop near the Cape Verde Islands by Friday or Saturday. The GFS ensemble forecast is also highlighting the Southwest Caribbean waters near the coasts of Nicaragua and Honduras may be an area to watch for development late this week. NHC is not yet highlighting either of these areas in their Monday morning Tropical Weather Outlook.


Figure 7. Tropical Storm Kalmaegi swirls to the south of the island of Taiwan at night, as seen from the International Space Station by astronaut Reid Wiseman ‏(@astro_reid) at 3 pm EDT September 14, 2014. At the time, Kalmaegi had just crossed the Philippines' Luzon Island as a Category 1 typhoon, and had weakened to a tropical storm with 70 mph winds. Hong Kong is the other bright patch of lights. Image credit: Reid Wiswman.

Typhoon Kalmaegi hits the Philippines
In the Western Pacific, Category 1 Typhoon Kalmaegi hit Luzon Island in the Philippines on Sunday as a Category 1 storm with 80 mph winds, but weakened to a tropical storm with 70 mph winds by the time it emerged into the South China Sea. Kalmaegi has re-intensified into a Category 1 typhoon with 75 mph winds, and is expected to make landfall near China's Hainan Island south of Hong Kong on Tuesday.

Jeff Masters

Hurricane

Dangerous Category 3 Odile Bearing Down on Baja

By: JeffMasters, 10:43 PM GMT on September 14, 2014

Dangerous Category 3 Hurricane Odile is bearing down on Mexico's Baja Peninsula as the storm steams north-northwestwards at 14 mph towards the southwestern tip of Baja. Odile is likely to be the strongest or second strongest hurricane on record to affect Southern Baja. An Air Force hurricane hunter plane was in Odile Sunday afternoon, and measured top surface winds of 125 mph, with a surface pressure of 922 mb. This pressure puts Odile in pretty select company--only two other Eastern Pacific hurricanes have had lower pressures measured in them by the Hurricane Hunters--though a total of eleven Eastern Pacific hurricanes have had lower pressures, if we include satellite-estimated pressures. The only major hurricane on record to affect Southern Baja was Hurricane Kiko of 1989, which moved ashore on the Gulf of California side of the peninsula just south of La Paz as a Category 3 storm with 120 mph winds.


Figure 1. MODIS satellite image of Hurricane Odile off the coast of Mexico's Baja Peninsula, taken at approximately 2 pm EDT Sunday September 14, 2014. At the time, Odile was a Category 3 storm with 125 mph winds. Image credit: NASA.


Figure 2. Radar image of Hurricane Odile taken at 4:46 EDT Sunday, September 14, 2014. Image credit: Conagua.

Odile put on an impressive burst of rapid intensification Saturday night, going from a Category 1 hurricane with 75 mph winds to a Category 4 storm with 135 mph winds in just 24 hours. Satellite loops show that Odile has a large eye and impressive area of very intense eyewall thunderstorms. The eyewall of Odile is likely to pass over or just to the west of the southern tip of the Baja Peninsula just before midnight PDT Sunday night. The 2 pm PDT Sunday NHC Wind Probability Forecast gave Cabo San Lucas on the southwestern tip of the Baja Peninsula a 99% chance of seeing tropical storm-force winds of 39+ mph, and a 84% chance of hurricane-force winds. These odds were 99% and 47%, respectively for San Jose del Cabo, about 30 miles farther to the northeast.


Figure 3. Tracks of all Category 2 and stronger hurricanes to pass within 75 miles of the southern tip of Mexico's Baja Peninsula (light circle) between 1949 - 2013. Only one major hurricane--Hurricane Kiko of 1989--hit Baja during this time span. Data taken from NOAA/CSC's Historical Hurricane Tracks website.

Links
Mexican radar
Villa del Palmar Beach Resort & Spa livecam in Cabo San Lucas

Jeff Masters

Hurricane

Dangerous Category 4 Odile Threatens Baja; Edouard Becomes a Hurricane

By: JeffMasters, 3:58 PM GMT on September 14, 2014

Hurricane Warnings are flying for Mexico's Baja Peninsula as dangerous Category 4 Hurricane Odile approaches. Odile put on an impressive burst of rapid intensification Saturday night, going from a Category 1 hurricane with 75 mph winds to a Category 4 storm with 135 mph winds in just 24 hours. Satellite loops show that Odile has likely topped out in strength, but the storm has a large area of very intense eyewall thunderstorms and a prominent eye. Odile's heavy rains have mostly remained offshore of Mexico, though an outer spiral band brushed the Southwest coast of Mainland Mexico on Saturday, bringing 0.31" of a rain and a wind gust of 32 mph to Manzanillo. Baja will not be so lucky. The eyewall of Odile is likely to pass over or just to the west of the southern tip of the Baja Peninsula just before midnight PDT Sunday night. The 11 am EDT Sunday NHC Wind Probability Forecast gave Cabo San Lucas on the southwestern tip of the Baja Peninsula a 99% chance of seeing tropical storm-force winds of 39+ mph, and a 47% chance of hurricane-force winds. These odds were 98% and 19%, respectively for San Jose del Cabo, about 30 miles farther to the northeast. Tropical moisture flowing northwards from Odile's circulation is likely to bring heavy rains to Northern Mexico and the Southwest U.S. late this week. An Air Force hurricane hunter aircraft will investigate Odile Sunday afternoon.


Figure 1. MODIS satellite image of Hurricane Odile off the coast of Mexico's Baja Peninsula, taken at approximately 4 pm EDT Saturday September 13, 2014. At the time, Odile was a Category 1 storm with 90 mph winds. Image credit: NASA.

Links
Mexican radar
Villa del Palmar Beach Resort & Spa webcam in Cabo San Lucas

An incredibly active year for major Eastern Pacific hurricanes
Odile's intensification into a Category 4 storm gives the Eastern Pacific east of 140°W seven major hurricanes so far this year. With the season typically only about two-thirds over by September 14, we have a decent chance of tying or beating the record of eight intense hurricanes in a season, set in 1992. The 2014 tally for the Eastern Pacific east of 140°W currently stands at 15 named storms, 10 hurricanes, and 7 intense hurricanes. An average Eastern Pacific hurricane season sees 15 named storms, 8 hurricanes, and 3 intense hurricanes during the entire year. The records for total number of named storms, hurricanes, and intense hurricanes were all set in 1992, with 25 named storms, 14 hurricanes, and 8 intense hurricanes. If we include the Central Pacific between 140°W and 180°W, these record tallies in 1992 were 28 named storms, 16 hurricanes, and 10 intense hurricanes, compared with the 2014 totals of 15 named storms, 11 hurricanes, and 8 intense hurricanes (Genevieve did not become a hurricane and then major hurricane until it crossed from the Eastern Pacific into the Central Pacific.) What's really remarkable about the 2014 season is the proportion of named storms that have intensified to major hurricane strength: 8 of 15, or more than 50%. That's really difficult to do, particularly when the cold water wakes left behind by previous major hurricanes chill down the sea surface temperatures.

Edouard becomes a hurricane; not a threat to land
The fourth hurricane of the 2014 Atlantic hurricane season is Edouard, which intensified into a Category 1 hurricane with 80 mph winds at 11 am EDT Sunday. Edouard continues chugging to the northwest at 16 mph over the Central Atlantic, and is not a threat to any land areas. Satellite images show that Edouard has a large area of heavy thunderstorms with an intermittent eye.


Figure 2. Latest satellite image of Edouard.

Quiet in the rest of the Atlantic
The two tropical disturbances we were following Saturday, Invest 92L in the Gulf of Mexico and Invest 93L a few hundred miles west of the Cape Verde Islands, have become disorganized due to excess dry air. None of the three reliable computer models for predicting tropical cyclone genesis develop these systems. There is a new tropical wave predicted to come off the coast of Africa on Thursday that the GFS and European models are predicting could develop near the Cape Verde Islands by Friday. NHC is not yet highlighting this tropical wave in their Tropical Weather Outlook.

Typhoon Kalmaegi hits the Philippines
In the Western Pacific, Category 1 Typhoon Kalmaegi made landfall over Luzon Island in the Philippines on Sunday as a Category 1 storm with 80 mph winds. Kalmaegi is expected lose strength as it passes over the mountainous terrain of Luzon, then re-intensify as it crosses the South China Sea early this week, before making landfall in China south of Hong Kong on Tuesday.

Jeff Masters

Hurricane

Gulf of Mexico Disturbance 92L Disorganized; Baja Watching Hurricane Odile

By: JeffMasters, 3:34 PM GMT on September 13, 2014

A small area of low pressure in the Gulf of Mexico a few hundred miles west of South Florida (Invest 92L) is bringing heavy rains to the waters of the Florida Straits, but satellite loops show that this activity is poorly organized. Strong upper level winds out of the north are creating a moderately high 15 - 20 knots of wind shear, and the atmosphere is fairly dry to the north, interfering with development. Ocean temperatures are a very warm 30°C (86°F) over the Gulf, but the presence of dry air and high wind shear of 15 - 25 knots should keep any development slow until 92L moves inland over Texas on Monday night. Heavy rains from 92L will begin affecting Texas and the Mexican coast south of the Texas border on Monday, with 1 - 3" or rain possible Monday through Tuesday. None of the three reliable computer models for predicting tropical cyclone genesis develop 92L over the Gulf of Mexico. In their 2 pm EDT Saturday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odds of development odds of 10%. The Hurricane Hunters are on call to investigate 92L on Sunday afternoon, if neccessary.


Figure 1. Latest satellite image of Invest 92L.

Tropical Storm Edouard not a threat to land
Tropical Storm Edouard continues chugging to the northwest at 12 mph over the Central Atlantic, and is not a threat to any land areas. Satellite images show that Edouard has lost most of its heavy thunderstorms, but the storm remains well-organized. With wind shear expected to diminish by Sunday and ocean temperatures expected to be warm, the official NHC forecast of Edouard becoming a Category 1 hurricane by Sunday night appears to be on track.


Figure 2. Latest satellite image of Edouard.

Tropical wave 93L
A tropical wave (93L) that emerged from the coast of Africa on Thursday was located a few hundred miles southwest of the Cape Verde Islands on Saturday morning, and was headed west to west-northwest at 10 mph. Satellite images show 93L has a good degree of spin and is fairly well-organized, but has little heavy thunderstorm activity. The system is headed into a region with cooler waters and dry air, and none of the three reliable computer models for predicting tropical cyclone genesis develop 93L. In their 2 pm EDT Saturday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odds of development odds of 10%.


Figure 3. MODIS true-color image of Invest 93L off the coast of Africa, at approximately 8 am EDT September 13, 2014. Image credit: NASA.

Odile becomes a hurricane
In the Eastern Pacific, Hurricane Odile became the 11th hurricane of season Saturday morning, intensifying to a Category 1 storm with 80 mph winds at 11 am EDT. Satellite loops show that Odile continues to grow more organized, but the hurricane's heavy rains are remaining offshore of Mexico. Odile may be undergoing a period of rapid intensification that will take it to at least Category 2 strength; the 12Z Saturday run of the SHIPS model gave Odile a 55% chance of intensifying by 30 mph in 24 hours. While all of the reliable computer models show Odile will track northwest and remain offshore of the southern tip of the Baja Peninsula, just a slight deviation to the east would bring tropical storm conditions to the coast. The 11 am EDT Saturday NHC Wind Probability Forecast gave Cabo San Lucas on the tip of the Baja Peninsula a 51% chance of seeing tropical storm-force winds of 39+ mph , and a 6% chance of hurricane-force winds. As Odile passes southern Baja on Monday, the computer models grow more divergent in their forecast for the hurricane's track, with several reliable models (the European and UKMET) showing landfall over the Central Baja Peninsula. The GFS model keeps the storm out to sea. Regardless of the track, tropical moisture flowing northwards from Odile's circulation is likely to bring heavy rains to Northern Mexico and the Southwest U.S. by the middle of the week.

Typhoon Kalmaegi forms east of the Philippines
In the Western Pacific, Category 1 Typhoon Kalmaegi continues to gather strength in the waters east of the Philippines, and is on course to hit the Philippines' Luzon Island on Sunday. Kalmaegi is then expected to cross the South China Sea and impact China early next week.

Hurricane expert Steve Gregory has a more detailed look at 92L and the rest of the tropics in his latest post.

Jeff Masters

Hurricane

92L Bringing Heavy Rains to Florida; Edouard Forms in Central Atlantic

By: JeffMasters, 2:27 PM GMT on September 12, 2014

A small area of low pressure over South Florida (Invest 92L) is bringing heavy rains to South Florida and the waters of the Florida Straits, but Miami radar and satellite loops show that this activity is less organized than on Thursday. Strong upper level winds out of the north-northeast are creating a high 20 - 25 knots of wind shear, and the atmosphere is moderately dry to the north, interfering with development. While the circulation center of 92L is over land, development into a tropical depression is unlikely, but once the current westward 5 - 10 mph motion of 92L carries it over the Gulf of Mexico on Saturday, development odds will increase. Ocean temperatures are a very warm 30°C (86°F) over the Eastern Gulf, but the presence of dry air and high wind shear of 15 - 25 knots should keep any development slow. As of Friday morning, rainfall amounts from 92L were mostly below 1" over South Florida, but the disturbance will be capable of dumping additional rains of 1 - 3" over the area through Saturday. Heavy rains from 92L will begin affecting Texas and the Mexican coast south of the Texas border on Monday, with the center of 92L likely to move ashore over Texas on Monday evening or Tuesday morning. None of the three reliable computer models for predicting tropical cyclone genesis develop 92L over the Gulf of Mexico. In their 8 am EDT Friday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odds of development odds of 20% and 40%, respectively. I put these odds higher, at 30% and 50%, respectively. The Hurricane Hunters are on call to investigate 92L on Saturday afternoon.


Figure 1. MODIS satellite image of Invest 92L over Florida, taken at approximately 12:30 pm EDT Friday September 12, 2014. Image credit: NASA.

Tropical Storm Edouard not a threat to land
Tropical Storm Edouard formed Thursday night in the Central Atlantic about 1000 miles west of the Cape Verde Islands. Edouard's formation date of September 12 came almost two weeks later than the typical August 31 formation date for the Atlantic's fifth named storm of the season. Satellite images show that Edouard is steadily organizing, and the official NHC forecast of Edouard becoming a Category 1 hurricane early next week appears to be on track. Edouard is not a threat to any land areas.


Figure 2. Latest satellite image of Edouard.

New African tropical wave 93L emerges
A well-organized tropical wave with plenty of spin (93L) emerged from the coast of Africa on Thursday, and was located a few hundred miles south of the Cape Verde Islands on Friday morning. Satellite images show 93L has only a small area of heavy thunderstorms, but the system already has some low-level spiral bands. Ocean temperatures are a very warm 28°C (82°F), wind shear is moderate (10 - 15 knots), and the atmosphere is moderately moist. None of the three reliable computer models for predicting tropical cyclone genesis develop 93L. In their 8 am EDT Friday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odd of development odds of 20%. Given 93L's well-organized appearance on satellite images late Friday morning, I would put these odds at 40%. The storm is headed west-northwest at about 10 mph, and is unlikely to affect the Lesser Antilles Islands.

Tropical Storm Odile's rains avoiding Mexico
In the Eastern Pacific, Tropical Storm Odile is nearing hurricane strength, but satellite loops show that Odile's heavy rains are remaining offshore of Mexico as the storm moves northwest, parallel to the coast. Tropical moisture flowing northwards from Odile's circulation may bring heavy rains to Northern Mexico and the Southwest U.S. late next week.

Tropical Storm Kalmaegi forms east of the Philippines
In the Western Pacific, Tropical Storm Kalmaegi is gathering strength in the waters east of the Philippines, and is on course to intensify into a typhoon that will hit the Philippines' Luzon Island on Sunday. Kalmaegi is then expected to cross the South China Sea and impact China early next week.

Hurricane expert Steve Gregory has a more detailed look at 92L and the rest of the tropics in his latest post.

Jeff Masters

Hurricane

Halfway Point of Hurricane Season Arrives; TD 6 Forms in Central Atlantic

By: JeffMasters, 3:04 PM GMT on September 11, 2014

September 11 marks the halfway point of the Atlantic hurricane season (based on the past 100 years of data, 1914-2013)--and we're doing much better than usual so far. Only four named storms have formed, with three becoming hurricanes (and no major hurricanes.) An average Atlantic hurricane season has 6 named storms, 3 hurricanes, and 1 intense hurricane by the mid-point of the season. The four storms so far in 2014 have inflicted much less punishment than usual for half of a hurricane season. Hurricane Arthur made landfall in North Carolina as a Category 2 hurricane then blasted the Maritime Provinces of Canada as a powerful hurricane-force extratropical storm, but damage was low by Category 2 hurricane standards--just $14 million, with most of the damage occurring in Canada. Hurricane Bertha caused two deaths along the U.S. East Coast due to rough surf and strong rip currents, but did insignificant damage as it recurved out to sea, just off the coast. Hurricane Cristobal also did minimal damage, but killed a total of seven people--three swimmers in the U.S., and flood victims in Haiti (2), the Dominican Republic, and the Turks and Caicos Islands. Tropical Storm Dolly, which made landfall in northeastern Mexico on September 2 with 50 mph winds and torrential rains, killed one person and did millions in damage. Residents of Hurricane Alley shouldn't assume the rest of the season will end with a whimper, though. All it takes is one bad hurricane to make a ruinous hurricane season. Recall that 2012's worst storm--Hurricane Sandy--didn't occur until the third week of October!



Bahamas disturbance 92L struggling to develop
A small area of low pressure over the Northwest Bahamas (Invest 92L) has become more organized since Wednesday, but has limited heavy thunderstorm activity. Long range radar out of Melbourne, Florida shows that 92L has low-level spiral bands with a good degree of rotation, and satellite loops show that a small surface circulation has developed. However, strong upper level winds out of the north-northeast are creating a high 20 - 25 knots of wind shear, and the atmosphere is quite dry to the north, making development of 92L unlikely today and Friday. The current westwards 5 - 10 mph motion of 92L will carry the disturbance over Florida on Friday, and the storm should emerge over the Gulf of Mexico on Saturday. Ocean temperatures are a very warm 30°C (86°F) over the Eastern Gulf, but the presence of dry air and high wind shear of 15 - 25 knots should keep any development of 92L over the Gulf of Mexico slow. The disturbance will likely bring rains of 1 - 3" to much of Florida through Sunday. One of the three reliable computer models for predicting tropical cyclone genesis, the UKMET model, does develop 92L over the Gulf of Mexico. In their 2 pm EDT Thursday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odd of development odds of 30% and 30%, respectively.


Figure 1. MODIS satellite image of Invest 92L off the coast of Florida, taken at approximately 11:30 am EDT Thursday September 11, 2014. Image credit: NASA/GSFC.

Central Atlantic Tropical Depression Six not a threat to land
Tropical Depression Six has formed in the Central Atlantic about 750 miles west of the Cape Verde Islands, and is headed northwest at about 15 mph. Satellite images show TD 6 has a moderate amount of spin and heavy thunderstorm activity, and these thunderstorms are becoming more organized. The disturbance is embedded in a moderately moist air mass, has marginally warm (SSTs) of 27°C (81°F) beneath it, and is experiencing light wind shear. These conditions favor continued development. The 8 am EDT Thursday run of the SHIPS model predicted that wind shear would remain light to moderate (5 - 20 knots) and the atmosphere at mid-levels of the atmosphere (between 500 - 700 mb) would remain moderately moist this week, favoring development. TD 6 does not appear to be a long-range threat to the Lesser Antilles Islands, U.S. East Coast, or Bermuda. It remains to be seen if TD 6 will be a threat to the Canadian Maritime Provinces late next week.


Figure 2. Latest satellite image of Tropical Depression Six.

Flood threat to Mexico from Tropical Storm Odile diminishes
In the Eastern Pacific, Tropical Storm Odile formed on Wednesday morning a few hundred miles southwest of Acapulco. Satellite loops show that Odile has a large area of heavy thunderstorms that are slowly organizing, but the heavy rains of the storm are remaining just offshore of the Pacific coast of Mexico. If Odile follows the current projections from our two top track models, the GFS and European, these rains will remain offshore as the storm moves northwest, parallel to the coast. If the storm deviates to the right of its expected path, it will be capable of dumping 5 - 10" of rain along the coast from Acapulco to Puerto Vallarta.

Why has the Eastern Pacific been so active?
It's been a remarkably active hurricane season in the Eastern Pacific; Odile's formation gives the basin 15 named storms, 10 hurricanes, and 7 intense hurricanes so far this year. An average Eastern Pacific hurricane season sees 15 named storms, 8 hurricanes, and 3 intense hurricanes during the entire year, with about 2/3 of that activity occurring by September 9. Since July, the Eastern Pacific has had ocean temperatures about 0.6°C (1°F) above average and wind shear about 20% below average. The region has been dominated by moist, rising air and low pressure, leading to above average vertical instability. All of these factors are favorable for an active hurricane season. The Atlantic and Eastern Pacific are usually out of phase with their hurricane seasons--when one is active, the other is inactive. This occurs because when the large-scale atmospheric circulation favors rising air and low pressure over one ocean basin, there must be high pressure and dry, sinking air elsewhere to compensate--which typically occurs over the neighboring ocean basin, suppressing hurricane activity there.


Figure 3. Sea Surface Temperatures (SSTs) over the Eastern Pacific in 2014 (blue line) compared to average (black line.) SSTs have been up to 0.6°C (1°F) above average during the summer, increasing the potential for tropical storm formation. Image credit: NOAA/NESDIS/CIRA.


Figure 4. Vertical wind shear (in knots) over the Eastern Pacific in 2014 (blue line) compared to average (black line.) Wind shear has been about 20% below average during the summer, increasing the potential for tropical storm formation. Image credit: NOAA/NESDIS/CIRA.


Figure 5. Vertical instability over the Eastern Pacific in 2014 (blue line) compared to average (black line.) The instability is plotted in °C, as a difference in temperature from near the surface to the upper atmosphere. Thunderstorms grow much more readily when vertical instability is high. Instability has been higher than average during most of the summer, increasing the potential for tropical storm formation. Image credit: NOAA/NESDIS/CIRA.

Tropical Depression 15 forms east of the Philippines
In the Western Pacific, Tropical Depression Fifteen is organizing in the waters east of the Philippines, and is on course to intensify into a typhoon and potentially affect the northern portion of the Philippines' Luzon Island on Sunday. TD 15 will then potentially impact China early next week.

Twenty-five years ago on this date
On September 11, 1989, Tropical Depression Twelve continued to grow more organized, building a large region of heavy thunderstorms near its center. Two hooking spiral bands formed, prompting the National Hurricane Center to upgrade the depression to a tropical storm in their 11 am advisory. The new storm's name: Hugo. Tropical Storm Hugo headed westward across the open Atlantic at 20 mph, still four days from the Lesser Antilles Islands.

That day at NOAA's Miami-based Office of Aircraft Operations--the hurricane hunting division of NOAA--I joked with my colleagues about the fearsome new storm with the same name as the director of NOAA's Atlantic Oceanographic and Marine Laboratory (AOML), Hugo Bezdek. AOML housed the offices of NOAA's Hurricane Research Division, whose scientists would decide whether or not our hurricane hunting group would intercept the new storm once it got close enough to the Lesser Antilles Islands. Even if Hugo was a dud, we figured we'd be flying the storm for sure, since it shared the same first name as the big boss of the hurricane research scientists. We did not suspect at all that this storm named Hugo would go on to be the most destructive hurricane ever seen in the Atlantic.


Figure 6. AVHRR visible satellite image of Tropical Storm Hugo taken on September 11, 1989. Image credit: Google Earth rendition of the NOAA HURSAT data base.

Hurricane expert Steve Gregory has a more detailed look at 92L and the rest of the tropics in his latest post.

Jeff Masters

Hurricane

Futuristic 3-D Weather Graphics Grace the Weather Forecast for 2050

By: JeffMasters, 6:54 PM GMT on September 10, 2014

Futuristic and creative 3-D weather graphics like you've never seen before light up the screen in today's impressive forecast for September 23, 2050 released by the Weather Channel. The video was made in response to an appeal by the World Meteorological Organization (WMO) to television weather presenters world-wide to imagine a “weather report from the year 2050,” based on the best science we have as summarized in the 2014 Intergovernmental Panel on Climate Change (IPCC) report. If humanity’s current "business as usual" approach to emissions of heat-trapping gases like carbon dioxide continues, the average temperature of the Earth’s lower atmosphere could rise more than 4°C (7.2°F) by the end of the 21st century. But what does a global average temperature rise really mean? How would we experience it on a daily basis? Each day between now and the convening of the key 2014 climate summit in New York City the week of September 21, 2014--when the leaders of the world will assemble to lay out the road map to the crucial December 2015 climate negotiations in Paris--the WMO will release a new "Weather Report From 2050" on their website. Today's video from the Weather Channel imagines a future when it wouldn't take a landfalling hurricane to push water levels two feet above normal in Miami Beach--the onshore winds of a hurricane passing 400 miles offshore could cause that level of flooding, due to sea level rise. The report also envisions that the current 15-year drought affecting the Southwest U.S. will continue into 2050, becoming a decades-long "megadrought". On the lighter side, we hear about a new baseball team called the "Alberta Clippers" (named after a type of fast-moving snowstorm that originates in Alberta), and see Jim Cantore calling up hurricane tracking charts on his outstretched hand. It's a unique and impressive effort well-worth checking out, and will air on The Weather Channel's cable station throughout the day today (Wednesday.) I'll be featured in a separate behind-the-scences look at how we came up with the weather stories featured in the video.


Video 1. The daily weather forecast for September 23, 2050, as imagined by The Weather Channel.

Jeff Masters

Climate Change

Two Minor Atlantic Threat Areas; Odile a Serious Rainfall Threat for Mexico

By: JeffMasters, 1:51 PM GMT on September 10, 2014

A tropical wave (91L) located about 600 miles west-southwest of the Cape Verde Islands is headed west-northwest at about 15 mph. Satellite images show 91L has a moderate amount of spin and heavy thunderstorm activity, and these thunderstorms are poorly organized. The disturbance is embedded in a moist air mass, has moderately warm (SSTs) of 28°C (83°F) beneath it, and is experiencing light wind shear. These conditions favor development. The 8 am EDT Wednesday run of the SHIPS model predicted that wind shear would remain light to moderate (5 - 15 knots) and the atmosphere at mid-levels of the atmosphere (between 500 - 700 mb) would remain moist this week, favoring development. All three of our three reliable computer models for predicting tropical storm formation predict development of 91L over the next five days. In their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odd of development odds of 20% and 70%, respectively. A trough of low pressure expected to push off the U.S. East Coast early next week should induce a more northwesterly track for 91L next week, and the disturbance does not appear to be a long-range threat to the Lesser Antilles Islands or U.S. East Coast. It remains to be seen if 91L will be a threat to Bermuda or the Canadian Maritime Provinces late next week.


Figure 1. Visible satellite image of Invest 91L 600 miles west-southwest of the Cape Verde Islands at 8 am EDT September 10, 2014.

Bahamas disturbance 92L very disorganized
A weak area of low pressure over the Bahamas (92L) is bringing a few heavy rain showers to the islands, but this this activity is disorganized. Although wind shear is a moderate 10 - 20 knots and ocean temperatures are a very warm 30°C (86°F), the presence of dry air and cold air aloft associated with an upper level low will allow only slow development of the disturbance as it drifts westwards at 5 - 10 mph. The disturbance should move over Florida on Friday and emerge over the Gulf of Mexico on Saturday, bringing rains of 1 - 3" to much of Florida. None of the three reliable computer models for predicting tropical cyclone genesis develop the disturbance. In their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odd of development odds of 10% and 20%, respectively.

Tropical Storm Odile a serious flooding threat for Mexico
In the Eastern Pacific, Tropical Storm Odile formed on Wednesday morning a few hundred miles southwest of Acapulco. Satellite loops show that Odile has an imposing area of heavy thunderstorms that are steadily organizing, and this storm represents a serious rainfall threat to the Pacific coast of Mexico. The slow-moving storm will be capable of dumping 5 - 10" of rain along the coast from Acapulco to Puerto Vallarta beginning on Thursday.


Figure 2. Predicted rainfall along the track of Odile from the 06Z (2 am EDT) September 10, 2014 run of the GFDL model. The model predicted that TD 15-E would be a strong tropical storm or Category 1 hurricane as it brushed the coast of Mexico this week, bringing widespread rains of 8 - 16" along the coast from Acapulco to Manzanillo. Image credit: NOAA/GFDL.

Moisture from Hurricane Norbert and Tropical Storm Dolly brings heavy rains to U.S.
The counter-clockwise flow of air around Hurricane Norbert, which dissipated off the coast of Mexico's Baja Peninsula over the weekend, pulled moisture from the remnants of Tropical Storm Dolly and from the tropical Eastern Pacific northwards into Northern Mexico and Southern Arizona, bringing epic rainfall amounts and severe flooding on Monday. According to Wunderground's weather historian Christopher C. Burt in his latest post, the official weather site at Phoenix’s Sky Harbor International Airport has its rainiest day in recorded history on Monday, with 3.29” falling. Moisture from Norbert also helped contribute to torrential rains that affected Northern Missouri on Tuesday night into Wednesday morning. As of 8 am EDT Wednesday, 10.54" was recorded in 12 hours in Browning, MO, with 9.61" inches falling at Chillicothe. Moisture from Norbert will spread all the way into Michigan's Upper Peninsula on Wednesday afternoon, and an Areal Flood Watch is posted there for flooding rains of 1 - 3".


Figure 3. The remnants of Hurricane Norbert lie off the coast of Baja, Mexico at 7 pm EDT September 9, 2014, in this photo taken from the International Space Station by Reid Wiseman.

WSI's Mike Ventrice has a technical post on the Atlantic hurricane outlook for the next two weeks at the WSI WeatherWise blog.

Hurricane expert Steve Gregory has a more detailed look at the tropics as well as a discussion of the record rainfall in Arizona yesterday in his latest post.

Jeff Masters

Hurricane

Monsoon Floods Kill 420 in India and Pakistan

By: Jeff Masters , 3:09 PM GMT on September 09, 2014

Torrential monsoon rains of over 12" (305 mm) lashed the India-Pakistan border region of Kashmir and Jammu Provinces on September 3 - 7, triggering devastating floods that swept through the mountainous region, killing at least 420 people, according to Reuters. Thousands more have been trapped by flood waters, and on the Indian side of the border, over 2,000 villages have been inundated, along with the major city of Srinagar. The heavy rains fell in what has been a below-average monsoon season, with rainfall from June 1 - September 3 totaling 15% below average over India and 32% below average over the flood-hit northern provinces of Jammu and Kashmir, according to the India Meteorological Department.


Figure 1. A temple is partially submerged in floodwaters in Jammu, India, Saturday, Sept. 6, 2014. (AP Photo/Channi Anand)


Figure 2. Precipitation totals for the seven-day period ending at 18 UTC September 8, 2014, show that up to 14" (356 mm) fell along the India-Pakistan border in Kashmir. Image credit: NASA/TRMM.


Figure 3. MODIS true-color image of a powerful monsoon low over the India-Pakistan border region of Kashmir on September 5, 2014. Image credit: NASA.

Catastrophic floods: the new normal in Pakistan
In Pakistan, where at least 207 people died in the past weeks' flooding, crippling and catastrophic floods have become the new normal. The past four consecutive monsoon seasons--2013, 2012, 2011, and 2010--have all seen top-five most expensive flood disasters in Pakistani history. The worst came in 2010, when the second heaviest monsoon rains of the past 50 years triggered rampaging floods that inundated one-fifth of the country, killing 1,985 people and causing a staggering $9.5 billion in damage--4% of the nation's GDP--according to the International Disaster Database, EM-DAT. Part of the reason for the increase in destructive flooding is due to poor flood control infrastructure, combined with a rising population and ineffective government policies.


Figure 4. Kashmiri residents struggle to withstand sudden and strong water currents while wading through floodwaters in their efforts to move to safer places in Srinagar, India, Thursday, Sept. 4, 2014. (AP Photo/Dar Yasin)

Heavy monsoon rainfall events are increasing
A warming climate loads the dice in favor of heavier extreme precipitation events. This occurs because more water vapor can evaporate into a warmer atmosphere, increasing the chances of record heavy downpours. In a study published in Science in 2006, Goswami et al. found that the level of heavy rainfall activity in the monsoon over India had more than doubled in the 50 years since the 1950s, leading to an increased disaster potential from heavy flooding. Moderate and weak rain events decreased during those 50 years, leaving the total amount of rain deposited by the monsoon roughly constant. The authors commented, "These findings are in tune with model projections and some observations that indicate an increase in heavy rain events and a decrease in weak events under global warming scenarios." However, a 2011 study by Ghosh et al., "Lack of uniform trends but increasing spatial variability in observed Indian rainfall extremes", cautioned that the observed increase in heavy precipitation events in India had a very complicated pattern that was not easily quantified. In general, we should expect to see an increased number of disastrous monsoon floods in coming decades if the climate continues to warm as expected. Since the population continues to increase at a rapid rate in the region, death tolls from monsoon flooding disasters are likely to climb dramatically in coming decades. However, my greater concern for India is drought. The monsoon rains often fail during El Niño years, and more than 4.2 million people died in India due to droughts between 1900 - 2012. Up until the late 1960s, it was common for the failure of the monsoon rains to kill millions of people in India. The drought of 1965 - 1967 killed at least 1.5 million people. However, since the Green Revolution of the late 1960s--a government initiative to improve food self-sufficiency using new technology and high-yield grains--failure of the monsoon rains has not led to mass starvation in India. It is uncertain whether of not the Green Revolution can keep up with India's booming population, and the potential that climate change might bring more severe droughts. Climate models show a wide range of possibilities for the future of the Indian monsoon, and it is unclear at present what the future might hold. However, the fact that one of the worst droughts in India's history occurred in 2009 shows that serious droughts have to be a major concern for the future. The five worst Indian monsoons along with the rainfall deficits for the nation:

1) 1877, -33%
2) 1899, -29%
3) 1918, -25%
4) 1972, -24%
5) 2009, -22%

References
Ghosh et al., "Lack of uniform trends but increasing spatial variability in observed Indian rainfall extremes", Nature Climate Change 2, 86–91 (2012) doi:10.1038/nclimate1327

Goswami, et al., 2006, " Increasing Trend of Extreme Rain Events Over India in a Warming Environment", Science, 1 December 2006:Vol. 314. no. 5804, pp. 1442 - 1445 DOI: 10.1126/science.1132027

Wunderground's climate change blogger Dr. Ricky Rood wrote a nice 3-part series about the challenges India faces due to climate change after he completed a 2009 trip there.

Over 500 killed in India's Monsoon Floods, my June 21, 2013 blog post

Tropical Wave 91L
A tropical wave (91L) located a few hundred miles south of the Cape Verde Islands is headed west-northwest at about 15 mph. Satellite images show 91L has a moderate amount of spin and a limited amount thunderstorm activity, and these thunderstorms are poorly organized. The disturbance is embedded in a moist air mass, has moderately warm (SSTs) of 28°C (83°F) beneath it, and is experiencing light wind shear. These conditions favor development. The 8 am EDT Tuesday run of the SHIPS model predicted that wind shear would remain light to moderate ( 5 - 15 knots) the atmosphere at mid-levels of the atmosphere (between 500 - 700 mb) will remain moist, favoring development. All three of our three reliable computer models for predicting tropical storm formation predict development of 91L over the next five days. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odd of development odds of 30% and 70%, respectively. A trough of low pressure expected to push off the U.S. East Coast early next week should induce a more northwesterly track for 91L next week, and the disturbance does not appear to be a long-range threat to the Lesser Antilles Islands. It remains to be seen if 91L will be a long-range threat to Bermuda, the U.S. East Coast, or the Canadian Maritime Provinces late next week.

Hurricane expert Steve Gregory has a more detailed look at the tropics as well as a discussion of the record rainfall in Arizona yesterday in his latest post.

Wunderground's weather historian Christopher C. Burt discusses the records rains in Arizona on Monday in his latest post.


97 Hours of Consensus
On Sunday, 9/7, the climate change myth-debunking website skepticalscience.com launched their 97 Hours of Consensus campaign addressing one of the most significant and harmful myths about climate change. Each hour, beginning at 9am Sunday, September 7, they began publishing a playful, hand-drawn caricature of a leading climate scientist along with a statement by them regarding climate change. Each caricature lists the scientists’ name, title, expertise and academic institution. 97 Hours of Consensus communicates the fact that 97% of climate scientists have concluded that humans are causing global warming. The research, conducted by scientists at The University of Queensland’s Global Change Institute, University of Reading, Michigan Technological University and Memorial University of Newfoundland found that 97% of relevant climate papers endorsed human-caused global warming. The paper was published in the academic journal Environmental Research Letters in May 2013. You can see the scientists without names at http://sks.to/97--click on the character for their name, quote, institution and expertise. Also watch as the 3% of dissenting scientists get added to the crowd. All the full quotes (with links to source and scientist bio page) are available at http://skepticalscience.com/graphics.php?c=9.

Jeff Masters

Flood

African Wave 91L Worth Watching; Record Quiet Spell Ends in Western Pacific

By: JeffMasters, 3:11 PM GMT on September 08, 2014

A tropical wave (91L) that emerged from the coast of Africa on Sunday is headed west to west-northwest at about 15 mph. Satellite images show 91L has a moderate amount of spin and heavy thunderstorm activity, but these thunderstorms are poorly organized. The disturbance is embedded in a moist air mass, has moderately warm (SSTs) of 27.5°C (82°F) beneath it, and is experiencing light wind shear. These conditions favor development. The 8 am EDT Monday run of the SHIPS model predicted that wind shear would remain light to moderate ( 5 - 15 knots) for the next five days, favoring continued development. However, development will be slowed by the fact that the atmosphere at mid-levels of the atmosphere (between 500 - 700 mb) should grow steadily grow drier. Two of our three reliable computer models for predicting tropical storm formation predict development of 91L over the next five days. In their 8 am EDT Monday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odd of development odds of 30% and 60%, respectively. A trough of low pressure expected to push off the U.S. East Coast early next week should induce a more northwesterly track for 91L next week, and the disturbance does not appear to be a long-range threat to the Lesser Antilles Islands. It remains to be seen if 91L will be a long-range threat to Bermuda, the U.S. East Coast, or the Canadian Maritime Provinces late next week.


Figure 1. MODIS satellite image of tropical wave 91L off the coast of Africa at approximately 8 am EDT Monday September 8, 2014. Image credit: NASA/GSFC.

Record quiet spell ends in Western Pacific
A remarkable month-long hiatus in tropical cyclone activity in the Western Pacific finally came to an end on Sunday, when Tropical Storm Fengshen formed a few hundred miles south of Japan. Prior to Fengshen, the last named storm to form in the Western Pacific was Tropical Storm Nakri, which formed on July 29 (according the Japan Meteorological Agency, the official agency responsible for typhoon warnings) or August 2 (according the U.S. Joint Typhoon Warning Center.) Typhoon Genevieve, which crossed the Dateline into the Western Pacific on August 7, originated in the Eastern Pacific, so doesn't count as a named storm originating in the Western Pacific. According to the archive of Japan Meteorological Agency Western Pacific typhoons kept at Digital Typhoon, August 2014 marks the first August since records began in 1951 that a tropical storm did not form in the Western Pacific. During the period 1951 - 2013, an average of 5.6 named storms formed in the basin during August. The previous record low for August was two named storms, which occurred in both 1979 and 1980. The lack of activity this August in the Northwest Pacific was due, in part, to an unfavorable phase of the Madden Julian Oscillation (MJO), a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days. The MJO caused dry, sinking air to predominate in the Western Pacific during August. Thanks to a busy July, the Western Pacific has seen 14 named storms so far this year, which is only one behind average.


Figure 2. MODIS satellite image of Tropical Storm Fengshen south of Japan, taken at approximately 03 UTC Monday September 8, 2014. At the time, Fengshen had top sustained winds of 65 mph. Image credit: NASA.

Jeff Masters

Hurricane

African Tropical Waves 90L and 91L Pose Little Threat

By: Jeff Masters , 3:26 PM GMT on September 07, 2014

Two tropical waves spinning off the coast of Africa are worth watching for development, but neither poses a foreseeable threat to any land areas. A tropical wave (90L) located about 700 hundred miles west of the Cape Verde Islands at 10 am EDT on Sunday is headed west to west-northwest at about 10 - 15 mph. Satellite images show 90L has plenty of spin, but heavy thunderstorm activity is limited. The disturbance is embedded in a very dry air mass, has marginal Sea Surface Temperatures (SSTs) of 26.5°C (80°F) beneath it, and is experiencing moderate wind shear. None of our three reliable computer models for predicting tropical storm formation predicts development of 90L over the next five days. In their 8 am EDT Sunday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odd of development odds of 10%. The wave should pass a few hundred miles northeast of the northern Lesser Antilles Islands on Thursday.


Figure 1. MODIS satellite image of tropical waves 90L and 91L off the coast of Africa at approximately 8 am EDT Sunday September 7, 2014. Image credit: NASA/GSFC.

New African Tropical Wave 91L
A tropical wave (91L) that emerged from the coast of Africa on Sunday is headed west to west-northwest at about 15 mph. Satellite images show 91L has a moderate amount of spin and heavy thunderstorm activity. The disturbance is embedded in a moist air mass, has moderately warm (SSTs) of 27.5°C (82°F) beneath it, and is experiencing moderate wind shear. Two of our three reliable computer models for predicting tropical storm formation predict development of 91L over the next five days. In their 8 am EDT Sunday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odd of development odds of 30% and 60%, respectively. The wave should take a more northwesterly track by mid-week, and does not appear to be a long-range threat to the Lesser Antilles Islands.

Norbert rapidly weakening
In the Eastern Pacific, Hurricane Norbert weakened to a tropical storm Sunday morning as it moved over cool waters of 25°C (77°F.) Satellite loops on Sunday morning showed that Norbert had lost almost all of its heavy thunderstorms. The current weakening trend should accelerate until Norbert dissipates by Monday. The counter-clockwise flow of air around the hurricane is pulling moisture from the remnants of Tropical Storm Dolly and from the tropical Eastern Pacific northwards into Northern Mexico and the Southern Arizona, and this moisture will be capable of causing flooding rains in those regions.

Jeff Masters

Hurricane

Norbert Hits Category 3; Three Minor Atlantic Threat Areas to Watch

By: Jeff Masters , 4:13 PM GMT on September 06, 2014

Hurricane Norbert put on an unexpected burst of rapid intensification overnight, topping out as a Category 3 storm with 120 mph winds at 5 am EDT Saturday. Norbert continues to chug parallel and just offshore from the coast of Mexico's Baja Peninsula, bringing heavy rain and tropical storm-force winds to the coast. Satellite loops on Saturday morning showed that Norbert had a small eye and some very impressive eyewall thunderstorms with cold cloud tops. However, the storm is starting to weaken, thanks to cooler ocean temperatures near 27°C (81 °F), and drier air. The models all show the core of the hurricane remaining just offshore as it moves northwest parallel to the Baja Peninsula over the next three days, so heavy rains of 3 - 6" causing flash flooding will be the primary threat from Norbert to Baja. The counter-clockwise flow of air around the hurricane is pulling moisture from the remnants of Tropical Storm Dolly and from the tropical Eastern Pacific northwards into Northern Mexico and the Southern Arizona, and this moisture will be capable of causing flooding rains in those regions.

Norbert's intensification into a Category 3 storm gives the Eastern Pacific seven major hurricanes so far this year. With the season typically only 2/3 over by September 9, we have a decent chance of tying or beating the record of ten intense hurricanes in a season, set in 1992 (this tally includes hurricanes in the Central Pacific.) The 2014 tally for the Eastern Pacific currently stands at 14 named storms, 10 hurricanes, and 7 intense hurricanes. An average Eastern Pacific hurricane season sees 15 named storms, 8 hurricanes, and 3 intense hurricanes during the entire year. The records for total number of named storms, hurricanes, and intense hurricanes were all set in 1992, with 28 named storms, 16 hurricanes, and 10 intense hurricanes (with the Central Pacific tallies included.)


Figure 1. Hurricane Norbert near Mexico's Baja Peninsula at 10:30 am EDT September 6, 2014. At the time, Norbert was a Category 3 storm with 115 mph winds. Image credit: NASA/GSFC.


Figure 2. Predicted seven-day precipitation amounts for the period ending on Saturday, September 13 show a large area of 3+ inches are expected over Southeast U.S., thanks to a weak tropical disturbance. A region of 2+" of rain is expected over Southern Arizona due to the flow of moist air northwards caused by Hurricane Norbert's circulation. Image credit: NOAA/HPC.

Southeast U.S. disturbance bringing heavy rains
A weak area of low pressure near the coast of Georgia is bringing heavy rain showers to the Southeast U.S. coast and adjacent waters, but this this activity is very disorganized. The disturbance will bring heavy rains in excess of three inches to the coast over the next few days as the low drifts northeastward. After that time, the low will likely merge with a frontal zone over the ocean and head out to sea. In their 8 am EDT Saturday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odd of development odds of 0% and 10%, respectively.

Tropical Wave 90L
A tropical wave (90L) located a few hundred miles west of the Cape Verde Islands is headed west to west-northwest at about 15 mph. Satellite images show 90L has plenty of spin, but little heavy thunderstorm activity. Though Sea Surface Temperatures are fairly warm, 27.5°C (82°F), and wind shear is low, 90L is embedded in a very dry air mass that is expected to get dryer as the storm progresses westwards. None of our three reliable computer models for predicting tropical storm formation predicts development of 90L over the next five days. In their 8 am EDT Saturday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odd of development odds of 10%. The wave should arrive in the northern Lesser Antilles Islands by Wednesday night.

New African Tropical Wave
Following on the heels of 90L will be a new tropical wave that is expected to push off the coast of Africa on Sunday night or Monday morning, bringing heavy rain showers and gusty winds to the Cape Verde Islands on Monday and Tuesday. All three of our three reliable computer models for predicting tropical storm formation show development of the new wave by Wednesday. The new wave will see similar conditions to 90L, though, and will struggle with dry air and moderate wind shear. In their 8 am EDT Saturday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odd of development odds of 0% and 30%, respectively. The wave should take a more northwesterly track then 90L, and not threaten the Lesser Antilles Islands.

Jeff Masters

Hurricane

Norbert Drenching Baja; 90L Moving Through Cape Verde Islands

By: JeffMasters, 3:20 PM GMT on September 05, 2014

Hurricane Norbert continues to chug parallel and just offshore from the coast of Mexico's Baja Peninsula, bringing heavy rain and tropical storm-force winds to the coast. Sustained winds as Cabo San Lucas on the southern tip of the Baja Peninsula peaked at 32 mph at 7:43 pm Thursday evening before the airport shut for the night, and the airport recorded 7.4 inches (188 mm) of rain in a 24-hour period ending Friday morning. Satellite loops on Friday morning showed that Category 1 Norbert had no eye but some very intense eyewall thunderstorms with cold cloud tops. Norbert should be able to take advantage of warm SSTs, a moist atmosphere, and moderate wind shear and maintain Category 1 hurricane strength through Saturday morning. By Saturday evening, Norbert will encounter ocean temperatures below 26°C (79 °F), and drier air, which should induce a steady weakening trend. The models all show the core of the hurricane remaining just offshore as it moves northwest parallel to the Baja Peninsula, so heavy rains of 3 - 6" causing flash flooding will be the primary threat from Norbert to Baja. The counter-clockwise flow of air around the hurricane is pulling moisture from the remnants of Tropical Storm Dolly and from the tropical Eastern Pacific northwards into Northern Mexico and the Southwest U.S., and this moisture will be capable of causing flooding rains this weekend in those regions. The heaviest rains in the Southwest U.S. are expected to occur in Southeast New Mexico, where amounts in excess of 3" may fall, due to the assistance of a cold front not related to Hurricane Norbert.

Wunderground member webcamstraveldot has a webcam in Cabo San Lucas that is showing some impressive rough surf today.


Figure 1. MODIS true-color image of Hurricane Norbert near the tip of Mexico's Baja Peninsula at 4:25 pm EDT September 4, 2014. At the time, Norbert had top sustained winds of 90 mph. Image credit: NASA.


Figure 2. Predicted seven-day precipitation amounts for the period ending on Friday, September 12 show a large area of 3+ inches are expected over Southeast New Mexico, thanks to the flow of moist air northwards caused by Hurricane Norbert's circulation and the influence of a weekend cold front. Image credit: NOAA/HPC.

Tropical wave 90L
A tropical wave (90L) is bringing strong winds and heavy rain showers to the Cape Verde Islands off the coast of Africa on Friday as the wave moves west at about 15 mph. Satellite images show 90L has plenty of spin, but little heavy thunderstorm activity. Conditions are marginal for development, with moderate wind shear of 10 - 20 knots, marginal Sea Surface Temperatures of 27°C (81°F), and dry air to the north. One of our three reliable computer models for predicting tropical storm formation (the GFS) shows development of 90L over the next five days. In their 8 am EDT Friday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odd of development odds of 20% and 30%, respectively. The long-range Friday morning runs of the GFS and European ensemble models favored the storm taking a more west-northwesterly track into the open ocean next week, with a low threat to the Lesser Antilles Islands. The Atlantic is expected to be dominated by dry, sinking air next week, due to the phase of the Madden Julian Oscillation (MJO), a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days, so I expect that 90L will struggle to develop. The 2 am EDT Friday run of the SHIPS model showed 90L encountering increasingly dry air over the next five days in the face of moderate wind shear--conditions hostile for development.

Following on the heels of 90L will be a new tropical wave that is expected to push off the coast of Africa on Monday, bringing heavy rain showers and gusty winds to the Cape Verde Islands on Monday on Tuesday. Two of our three reliable computer models for predicting tropical storm formation (the GFS and UKMET) show development of the new wave by Wednesday. The new wave will see similar conditions to 90L, and will struggle with dry air and moderate wind shear.


Figure 3. The "Weather Report From 2050" video from the Japan Broadcasting Corporation imagines a future weather report for Japan with record heat waves and a Super Typhoon.

Weather Reports From 2050
If humanity’s current "business as usual" approach to emissions of heat-trapping gases like carbon dioxide continues, the average temperature of the Earth’s lower atmosphere could rise more than 4°C (7.2°F) by the end of the 21st century. But what does a global average temperature rise really mean? How would we experience it on a daily basis? To find out what could lie in store, the World Meteorological Organization (WMO) invited television weather presenters from around the world to imagine a “weather report from the year 2050.” Each day between now and the convening of the key 2014 climate summit in New York City the week of September 21, 2014--when the leaders of the world will assemble to lay out the road map to the crucial December 2015 climate negotiations in Paris--the WMO will release a new "Weather Report From 2050" on their website. Yesterday's video from the Japan Broadcasting Corporation imagined a future for Japan with record heat waves killing 6,500 people annually, the delay of fall colors in Kyoto until Christmas, the destruction of Okinawa's coral reefs due to increasing ocean acidity and temperature, and an increase in the numbers of Category 4 and 5 Super Typhoons hitting Japan. The Weather Channel's "Weather Report From 2050" video will be released on September 10. It's not to be missed!

Jeff Masters

Hurricane

New Go-To App for the iPad: WunderStation for Personal Weather Stations

By: JeffMasters, 4:46 PM GMT on September 04, 2014

The world's largest Personal Weather Station (PWS) network--Weather Underground's 37,000 individually-owned weather stations across the globe--just got a major software upgrade. WunderStation for iPad, released today (for free) in the App Store and on iPad, provides the weather enthusiast a fantastic interface to the world's most in-depth set of weather observations. Started in 2001, the Weather Underground PWS network was developed to address the growing need for our meteorologists to gain access to more granular data. The network allows us to access weather data from actual neighborhoods, not just from the closest airport, and our meteorologists spent over five years developing and testing a revolutionary forecasting system which produces weather forecasts specific for each personal weather station around the globe.





Some highlights of the new WunderStation for iPad App:
- View current conditions from any weather station including temperature, feels-like temperatures, wind speed and direction, wind gusts, humidity, dew point, pressure, rain accumulation and rate, and moon phase


- 10-day and hourly forecasts including temperature, feels like, dewpoint, pressure, humidity, chance of precipitation, cloud cover, wind speed and direction, sunrise and sunset


- Historical highs and lows for temperature, humidity, pressure, rain accumulation, rain rate, and dewpoint viewable by hour, day, week, month, or year, going back up to 3 years


- Sky conditions including sunrise, sunset, total hours of day, total hours of night, and moon phases


- Rainfall totals and rain rate, with ability to set your own water year


- Customizable graphs: overlay as many or as few measurements as you'd like and compare historical conditions


- Drag, drop, add or delete content widgets to create a customized experience according to your data preferences


- Animated wind direction, rainfall totals, and temperature


- Toggle between different viewing options: infographic or graph view


- View a map of all 37,000 weather stations in Weather Underground's network and save any station to your list


- Swipe right and left to view your saved stations



For PWS owners:
- Update your personal weather station's status to better serve others viewing your station's data


- Solar radiation and UV index widgets available for stations that have these extra sensors

For more info
For additional info on the app and to check out our fun promo video, visit wunderstation.com. Please share with your social networks as well.

Want to join our network? If you’re interested in setting up your own personal weather station or know someone who might be interested, let us know! For additional info on how to get started, visit: http://www.wunderground.com/weatherstation/about.asp.

WunderStation for iPad is available for free in the iTunes App Store.

Jeff Masters

Recent News

Hurricane Norbert Brushing Baja; 90L Emerges From the Coast of Africa

By: Jeff Masters , 12:42 PM GMT on September 04, 2014

Hurricane Norbert took advantage of unusually warm 29.5°C (85°F) Sea Surface Temperatures (SSTs) and intensified into the Eastern Pacific's tenth hurricane of the year on Wednesday evening. The Eastern Pacific has seen an unusually active hurricane season, with 14 named storms, 10 hurricanes, and 6 intense hurricanes so far. An average Eastern Pacific hurricane season sees 15 named storms, 8 hurricanes, and 3 intense hurricanes during the entire year, with about 2/3 of that activity occurring by September 9. Satellite loops on Thursday morning showed that Category 1 Norbert had no eye but some very intense eyewall thunderstorms with cold cloud tops, and Mexican radar showed an outer band of Norbert bringing heavy rains to the tip of the Baja Peninsula and adjacent areas of Mainland Mexico. Norbert should be able to take advantage of warm SSTs, a moist atmosphere, and moderate wind shear over the next two days to maintain Category 1 hurricane strength, but the models all show the core of the hurricane remaining just offshore as it moves northwest parallel to the Baja Peninsula. Norbert is a small storm, and it's hurricane-force winds are only expected to reach out about 25 miles from the center when it makes its closest pass by the tip of the Baja Peninsula on Thursday night and Friday morning. Hurricane force winds will likely stay offshore, but Baja can expect tropical storm-force winds from Norbert. In their 2 am PDT Thursday WInd Probability Advisory, NHC gave Cabo San Lucas on the southern tip of the Baja Peninsula a 63% chance of experiencing tropical storm-force winds of 39+ mph, and a 0% chance of experiencing hurricane-force winds of 74+ mph. Heavy rains of 3 - 5" causing flash flooding will be the primary threat from Norbert to Baja.


Figure 1. MODIS true-color image of Tropical Storm Norbert at approximately 5 pm EDT September 3, 2014. At the time, Norbert had top winds of 70 mph. Image credit: NASA.

New tropical wave 90L emerges from the African coast
A well-organized tropical wave (designated 90L by NHC on Thursday morning) has emerged from the coast of Africa, and is moving to the west at about 15 mph. Satellite images show the wave has plenty of spin, but little heavy thunderstorm activity. Wind shear is moderate, 10 - 20 knots, and the ocean temperatures are warm, near 28°C (82°F.) The core of the wave will pass a few hundred miles south of the Cape Verde Islands on Friday. Two of our three reliable computer models for predicting tropical storm formation show development by Monday, and in their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odd of development odds of 10% and 40%, respectively. The Thursday morning long-range runs of the GFS and European ensemble models favored the storm taking a more west-northwesterly track into the open ocean next week, with a low threat to the Lesser Antilles Islands indicated. The Atlantic is expected to be dominated by dry, sinking air next week, due to the phase of the Madden Julian Oscillation (MJO), a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days, so I expect that 90L will struggle to develop. Indeed, the 2 am EDT Thursday run of the SHIPS model showed 90L encountering increasingly dry air over the next five days in the face of moderate wind shear--conditions hostile for development.


Figure 2. MODIS true-color image of Invest 90L off the coast of Africa, at approximately 8 am EDT September 4, 2014. Image credit: NASA.

Jeff Masters

Hurricane

Tropical Storm Dolly Hits Mexico; Tropical Storm Norbert Threatening Baja

By: JeffMasters, 2:13 PM GMT on September 03, 2014

Tropical Storm Dolly made landfall on Mexico's Gulf of Mexico coast just south of Tampico near 11 pm EDT Tuesday night as a minimal tropical storm with 45 mph winds. While Dolly's winds will not cause major damage, the storm's rainfall has the potential to cause dangerous flash flooding and mudslides as Dolly pushes inland and dissipates today. Radar-estimated rainfall from the Brownsville, Texas radar showed areas of 2 - 4 inches of rain along the coast of Mexico as of Wednesday morning, and isolated rainfall amounts of up to 15" are expected from Dolly. Satellite loops on Wednesday morning showed that Dolly still had some very heavy thunderstorms over the warm waters just offshore from Tampico, though the storm had been downgraded to a tropical depression with 35 mph winds as of 7 am CDT on Wednesday.


Figure 1. Twin tropical storms besiege Mexico: Tropical Storm Dolly nears landfall along Mexico's Bay of Campeche (right) as Tropical Storm Norbert brushes the Pacific coast of Southwest Mexico (left) in this GOES-East image taken at 7:45 pm EDT September 2, 2014. At the time, both storms had 45 mph sustained winds. Image credit: NASA/Goddard Space Flight Center.


Figure 2. Radar-estimated rainfall from the Brownsville, Texas radar as of 9:49 am EDT on September 3, 2014, showed areas of 2 - 4" of rain had fallen along the coast of Mexico.

Tropical Storm Norbert a threat to Baja Mexico
In the Eastern Pacific, Tropical Storm Norbert is approaching hurricane strength in the waters south of the Baja Peninsula, taking advantage of unusually warm 29.5°C (85°F) Sea Surface Temperatures (SSTs.) These SSTs are about 2°C (3.6°F) warmer than average. Satellite loops on Wednesday morning showed that Norbert had developed some very intense eyewall thunderstorms with cold cloud tops, and microwave imagery showed an eye beginning to develop. Norbert should be able to take advantage of warm SSTs, a moist atmosphere, and moderate wind shear over the next two days to intensify into at least a Category 1 hurricane. The 5 am PDT run of the SHIPS model predicted a substantial 30% chance that Norbert could undergo rapid intensification from a tropical storm with 60 mph winds to a Category 2 hurricane with 100 mph winds by Thursday morning. However, Norbert is a small storm, and it's hurricane-force winds are only expected to reach out about 20 - 25 miles from the center when it makes its closest pass by the tip of the Baja Peninsula on Thursday night and Friday morning. In their 2 am PDT WInd Probability Advisory, NHC gave Cabo San Lucas on the southern tip of the Baja Peninsula a 72% chance of experiencing tropical storm-force winds of 39+ mph, and a 10% chance of experiencing hurricane-force winds of 74+ mph.


Figure 3. MODIS true-color image of a well-organized tropical wave preparing to move off the coast of Africa, at approximately 8 am EDT September 3, 2014. Image credit: NASA.

New African tropical wave this weekend may develop
A tropical wave is expected to come off the coast of Africa on Thursday and move to the west at about 15 mph. This wave will be capable of bringing heavy rain and strong winds to the Cape Verde Islands on Friday and Saturday. Two of our three reliable computer models for predicting tropical storm formation show development by Sunday of the wave, and in their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odd of development odds of 0% and 30%, respectively. The Wednesday morning runs of the GFS and European ensemble models favored the storm taking a more west-northwesterly track into the open ocean next week, with a low long-range threat to the Lesser Antilles Islands indicated. However, it is too early to be confident that the storm will miss the islands, as the long-range tracks have shifted closer to the Lesser Antilles since their runs on Tuesday. The Atlantic is expected to be dominated by dry, sinking air next week, due to the phase of the Madden Julian Oscillation (MJO), a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days, so I expect that any tropical waves crossing from Africa towards the Lesser Antilles will struggle to develop.

Jeff Masters

Hurricane

Tropical Storm Dolly Forms in the Gulf of Mexico

By: JeffMasters, 2:24 PM GMT on September 02, 2014

Say hello to the Atlantic's fourth named storm of 2014--Tropical Storm Dolly, which formed Tuesday morning in the Gulf of Mexico's Bay of Campeche. Radar loops out of Altamira, Mexico show Dolly's heavy thunderstorms were already beginning to move ashore over the coast of Mexico a few hundred miles south of the Texas border Tuesday morning, though the heaviest activity was still well offshore. Satellite loops on Tuesday morning showed the classic appearance of a tropical storm struggling with wind shear--a low level circulation center partially exposed to view, with the heavy thunderstorms limited to one side (the south side) by strong upper-level winds. Sea Surface Temperatures (SSTs) were very warm, near 30°C (86°F), but dry air to the north of Dolly was being driven into the center of the storm's circulation by strong upper-level winds from the north-northwest, keeping development slow. Dolly doesn't have long over water before it makes landfall on Wednesday morning, and likely will not have time to intensify into a hurricane, given the dry air to its north and continued moderate levels of wind shear expected to affect the storm. None of the Tuesday morning runs of the reliable hurricane intensity models showed Dolly becoming a hurricane. Heavy rain is the main threat of the storm, and Dolly's rains will be capable of generating dangerous flash floods and mudslides over the mountainous terrain of Mexico near and to the south of the landfall location. The heavy rain threat will be less to the north of the landfall location, due to the presence of dry air.


Figure 1. Latest satellite image of Dolly.

Say Hello, Dolly--again!
Dolly's formation on September 2 comes more than a week later than the usual formation date of the Atlantic's fourth named storm, August 23. The 2014 version of Tropical Storm Dolly is the eighth appearance of a storm named Dolly in the Atlantic. Dolly made its first appearance in 1953 as hurricane that weakened before passing over Bermuda. Dolly's most recent appearance, as a 2008 Category 2 hurricane that hit near the Texas/Mexico border, was its most damaging--$1.5 billion in losses were recorded. This was not enough to get the name Dolly retired, though, and I expect we will see the name Dolly get recycled again in 2020. (The record number of appearances of a storm name for the Atlantic is ten, held by Arlene.)

New African tropical wave this weekend may develop
A tropical wave is expected to come off the coast of Africa on Thursday and move to the west at about 15 mph. This wave will be capable of bringing heavy rain and strong winds to the Cape Verde Islands on Friday and Saturday. Our three reliable computer models for predicting tropical storm formation all show development by Saturday of the wave, and in their 8 am EDT Tuesday Tropical Weather Outlook, NHC gave the system 2-day and 5-day odd of development odds of 0% and 30%, respectively. The Tuesday morning runs of the GFS and European ensemble models favored the storm taking a more west-northwesterly track into the open ocean next week, with no long-range threat to the Lesser Antilles Islands indicated.

Tropical Storm Norbert a potential threat to Baja Mexico
In the Eastern Pacific, Tropical Storm Norbert is gathering strength a few hundred miles south of the southwestern coast of Mexico. Though Mexico's Baja Peninsula was not in NHC's cone of uncertainty for Friday, the 00Z Tuesday run of the reliable European model did show Norbert coming very close to Baja on Friday, and residents there should be alert to a possible shift in the predicted track of Norbert towards them in future NHC advisories. Satellite loops show that Norbert has plenty of heavy thunderstorms, but this activity was just offshore of Southwest Mexico on Tuesday morning. Norbert's formation on September 2 comes more than 5 weeks before the typical October 11 formation date of the season's fourteenth storm in the Eastern Pacific.

Jeff Masters

Hurricane

Invest 99L Organizing Over Gulf of Mexico

By: JeffMasters, 2:22 PM GMT on September 01, 2014

The center of a broad area of low pressure associated with tropical wave 99L is now over the warm waters of the Gulf of Mexico's Bay of Campeche, and the disturbance is growing more organized as it heads west-northwest at about 10 mph. Heavy rains are falling over Mexico's Yucatan Peninsula and southeastern Bay of Campeche coast, and radar loops out of Sabancuy, Mexico show a pronounced rotation to the echoes. Satellite loops on Monday morning showed the storm's heavy thunderstorm activity was increasing in intensity and organization, with a number of low-level spiral bands beginning to form. Sea Surface Temperatures (SSTs) were very warm, near 30°C (86°F), the atmosphere was moist, and wind shear was moderate, 15 - 20 knots. These conditions are favorable for development. The 8 am Monday run of the SHIPS model predicted that conditions will remain favorable for development over Bay of Campeche through Thursday, with moderate wind shear, a moist atmosphere, and warm SSTs of 30°C (86°F.) None of our three reliable computer models for predicting tropical storm formation showed 99L developing into Tropical Storm Dolly in their Monday morning runs. However, I expect that 99L will be at least a tropical depression by Tuesday morning. In their 8 am EDT Monday Tropical Weather Outlook, NHC gave 99L 2-day development odds into a tropical cyclone of 60% (a tropical cyclone is a generic term for all tropical depressions, tropical storms, and hurricanes.) The storm should continue to track to the west-northwest or northwest, with landfall occurring on the Mexican coast several hundred miles south of the Texas border on Tuesday or Wednesday morning. This likely will not give the storm time to intensify into a hurricane, though landfall as a strong tropical storm would not be a surprise. An Air Force hurricane hunter aircraft has been tasked to investigate 99L on Monday afternoon.


Figure 1. Latest satellite image of Invest 99L in the Western Caribbean.

New African tropical wave this weekend may develop
Our three reliable computer models for predicting tropical storm formation all show development by Saturday of a tropical wave expected to come off the coast of Africa on Friday. This wave will be capable of bringing heavy rain and strong winds to the Cape Verde Islands on Friday and Saturday.

Eastern Pacific's 93E a potential threat to Baja
In the Eastern Pacific, tropical disturbance Invest 93E is gathering strength a few hundred miles south of the southwestern coast of Mexico. In their Monday morning runs, both the GFS and European models predicted that 93E would develop into a tropical storm late this week, and pass very close to the tip of Mexico's Baja Peninsula on Friday. Satellite loops show that 93E is poorly organized today, and I expect that the earliest the disturbance would become a tropical depression is Wednesday. In their 8 am EDT Monday Tropical Weather Outlook, NHC gave 93E 2-day and 5-day odd of development of 20% and 70%, respectively.

Jeff Masters

Hurricane


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Category 6™

About

Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather