About Jeff Masters
Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather
By: JeffMasters, 1:27 PM GMT on April 30, 2010
The oil slick from the ruptured well due to the April 20 explosion and sinking of the offshore oil rig Deepwater Horizon has reached the Louisiana coast near the mouth of the Mississippi River. Strong southeasterly winds blowing at 20 - 25 knots will continue through Sunday, which will push a large amount of oil onto most of the eastern Louisiana coast from the mouth of the Mississippi River northwards to the Mississippi border. It is likely that the Mississippi coast will see the arrival of oil by Saturday night or Sunday. On Monday, the winds shift to southwesterly, but weaken. The wind shift will allow oil to move eastwards towards Alabama and the Florida Panhandle, but at just 1 mph or so. The winds remain southwesterly through Tuesday, which should allow the oil to reach Alabama by Monday and possibly the extreme western Florida Panhandle by Tuesday. On Tuesday night, a cold front is expected to move over the Gulf of Mexico, bringing offshore northwesterly winds. These offshore winds will last for two days and blow the oil slick 5 - 10 miles offshore. High pressure is expected to build in late next week, bringing relatively light offshore winds that should cause little transport of the oil spill for the final portion of next week.
Figure 1. The oil spill on April 29, 2010, as seen by the MODIS instrument on NASA's Terra spacecraft. A tendril of oil is beginning to touch the Mississippi River "bird's foot" in Louisiana. Sun glint on the water at this hour happened to be just at the right angle to light up the spill dramatically. Image credit: University of Wisconsin.
Oil continues to gush from the well head at 5,000 feet depth at a rate five times what was previously estimated--210,000 gallons per day. This is equivalent to about 2% of the total spilled oil from America's worst oil spill, the 1989 Exxon Valdez disaster in Alaska, entering the Gulf of Mexico each day. If 210,000 gallons per day has been leaking since the disaster began on April 20, over 2 million gallons of oil has already been spewed into the Gulf, about 20% of the 11,000,000 gallons spilled in the Exxon Valdez disaster.
Figure 2. Previous location and forecast location for today of the Deepwater Horizon oil spill. Image credit: NOAA Office of Response and Restoration.
Oil a long-range threat to southwest and southeast Florida, Cuba, and the Bahamas
The surface ocean currents that transport the oil are driven by the wind and by the large scale ocean current structure of the Gulf of Mexico. The latest surface ocean current forecast (Figure 3) from NOAA's RTOFS model shows a complicated current structure along the Gulf Coast over the next seven days. By Tuesday night, when the winds shift to northwesterly (offshore), the forecast calls for surface currents of about 1 m/s (roughly 2 mph) to transport oil to the southeast from the site of the blowout. There is a danger that the oil thus transported could make it all the way south to the Loop Current, since offshore winds are now expected to last Tuesday through Friday of next week. The warm Loop Current enters the Gulf from the south and loops around to the southeast to exit through the Florida Keys, where it becomes the Gulf Stream. Oil caught in the Loop Current would move relatively rapidly at 2 - 4 mph to the southeast and then eastwards through the Keys, potentially fouling beaches in the Keys, northwest Cuba, the southwest and southeast coasts of Florida, and the western Bahamas. I don't think the spill will be able to make it into the Loop Current next week, since it has to travel about 120 miles south-southeast from the blowout location to reach the Loop Current. The duration and strength of next week's offshore winds are probably capable of pushing the oil slick only half way to the Loop Current. However, that may be close enough so that the oil will reach the Loop Current the following week, unless strong onshore winds develop again. The long range wind forecast is too uncertain to put odds on the possibilities at this point. If the oil keeps spewing from the ocean floor for many months, though, eventually a wind pattern will set up that will take the oil into the Loop Current. This would most likely happen if a persistent trough of low pressure settles over the East Coast in May, or if a tropical storm makes landfall along the Florida Panhandle this summer. Any oil that does make it into the Loop Current will suffer significant dispersion before it makes landfall in Cuba, Florida, or the Bahamas, and far less oil will foul these shores compared to what the Louisiana coast is experiencing this weekend.
Figure 3. Surface ocean current forecast for 8pm EDT Tuesday, May 4 from the NOAA's RTOFS model run made at 8 pm EDT on Wednesday, April 28, 2010. Note that on Tuesday, northwest winds are expected to create surface currents of about 1 m/s (roughly 2 mph) from the site of the spill towards the southeast. It is possible that these currents will be strong enough to transport oil far enough south that it will enter the Loop Current, which would then transport the oil into northwest Cuba, the Florida Keys, and South Florida.
I'll probably do an update this weekend. Keep an eye on the severe weather threat in the Plains today and over the Mississippi and Ohio Valleys on Saturday. Our severe weather expert, Dr. Rob Carver, shows a few nice radar images of yesterday's strongest storms, which generated five tornadoes.
By: JeffMasters, 12:53 PM GMT on April 29, 2010
Work crews burned off oil on the surface of the Gulf of Mexico just 20 miles southeast of the Louisiana coast yesterday, in an effort to keep as much oil as possible from moving shoreward and fouling the beaches of the Gulf Coast. Relatively good weather, with moderate southeast winds of 10 - 15 knots, aided the efforts, and work crews were also able to use skimmers and dispersants to remove and thin the oil spill from the April 20 explosion and sinking of the offshore oil rig Deepwater Horizon. For now, it appears that the fires are not large enough to generate air pollution capable of causing health problems for those living downwind, according to the latest graphics from NOAA's Hazard Mapping System Fire and Smoke Product.
Oil continues to gush from the well head at 5,000 feet depth at a rate five times what was previously estimated--210,000 gallons per day. This is equivalent to about 2% of the total spilled oil from the 1989 Exxon Valdez disaster in Alaska entering the Gulf of Mexico each day. If 210,000 gallons per day has been leaking since the disaster began on April 20, over 2 million gallons of oil has already been spewed into the Gulf, about 18% of the 11,000,000 gallons spilled in America's previous worst oil spill, the Exxon Valdez disaster. With the winds expected to begin blowing the oil spill on shore this weekend, the Deepwater Horizon oil spill appears destined to become one of the most disastrous oil spills in U.S. history.
Figure 1. The oil spill on April 25, 2010, as seen by the MODIS instrument on NASA's Aqua spacecraft. Sun glint on the water at this hour happened to be just at the right angle to light up the spill dramatically. Image credit: NASA.
Figure 2. The oil spill on April 27, 2010, as seen by the MODIS instrument on NASA's Aqua spacecraft. The sun angle was not as favorable during this overpass to see the oil spill. The ability to detect oil slicks in photo-like satellite images is very sensitive to the viewing geometry--the angles between the surface, the Sun, and the satellite--at the time of the image. If the slick happens to be located in the sun glint part of the image, it may be very visible, but if not, it can be faint or even impossible to see.
The winds turn unfriendly
The winds have been relatively kind in the week since the Deepwater Horizon explosion, with offshore winds occurring frequently enough to keep the oil spill at least 20 miles from land. However, beginning today (Thursday), NOAA predicts that on-shore winds out of the southeast will increase to 15 - 20 knots, and strengthen to 20 - 25 knots tonight through Saturday night. These winds should be able to push the oil slick close to or on the coast by this weekend, along the Louisiana's Mississippi River "bird's foot" visible in the satellite images above. The winds will weaken to 10 - 20 knots on Sunday through Monday, but remain on-shore. It is not until Tuesday that offshore winds are expected, when a strong cold front should move into the Gulf of Mexico. These offshore winds will last for two days, then high pressure is expected to build in, bringing relatively light winds that should cause little transport of the oil spill for the final portion of next week. My guess is that the winds will not be able to push the oil all the way to the Florida Panhandle coast over the next ten days, but coastal areas from eastern Louisiana to Alabama will be at risk of getting oil.
Oil a long-range threat to southwest and southeast Florida, Cuba, and the Bahamas
The surface ocean currents that transport the oil are driven by the wind and by the large scale ocean current structure of the Gulf of Mexico. The latest surface ocean current forecast (Figure 3) from NOAA's RTOFS model indicates a complicated current structure along the Gulf Coast over the next seven days, making it difficult to predict exactly where the oil slick might go. The warm Loop Current enters the Gulf from the south and loops around to the southeast to exit through the Florida Keys. A counter-clockwise rotating cool eddy is located a few hundred miles south of the Florida Panhandle, and a clockwise-rotating warm eddy is located south of Louisiana's Mississippi Delta. If next Tuesday's cold front brings strong enough northwesterly winds to the oil spill region, it is possible that a portion of the spill will get caught in the circulation of these two eddies and sucked southwards into the Loop Current. If this occurs, the oil would be move relatively rapidly at 2 - 4 mph to the southeast and then eastwards through the Keys, potentially fouling beaches in the Keys, northwest Cuba, the southwest and southeast coasts of Florida, and the western Bahamas. Based on the movement of the spill earlier this week during offshore winds, I don't think the spill will be able to make it into the Loop Current next week. However, if the oil keeps spewing from the ocean floor for many months, eventually a wind pattern will set up that will take the oil into the Loop Current. This would most likely happen if a persistent trough of low pressure settles over the East Coast in May, or if a tropical storm makes landfall along the Florida Panhandle this summer. We're fortunate that there are no hurricanes to worry about right now, as the strong winds and storm surge of a hurricane would be able to drive the oil far inland along a wide swath of coast.
Figure 3. Surface ocean current forecast for 8pm Thursday from NOAA's RTOFS model. Forecast was made at 8 pm EDT on Tuesday, April 27, 2010.
Oil and coal are essential to modern society, and we need to continue extracting and transporting these fossil fuels to sustain our economy. However, we also need to be aware that the price we pay at the pump for gasoline does not include such expenses as the environmental damage from oil spills, nor the pollution from burning fossil fuels. Any debate about the costs of moving to more expensive but cleaner forms of energy needs to be honest about the tremendous costs due to environmental destruction and pollution that the mining and transport of fossil fuels cause--not to mention the death toll from oil drilling operations, oil refinery accidents, crashes of oil tanker trucks, and wars fought over oil.
Figure 4. Fire boat response crews battle the blazing remnants of the offshore oil rig Deepwater Horizon, April 21, 2010. Note the list of the platform. Image credit: USCG.
I'll have an update Friday or Saturday. Keep an eye on the severe weather threat in the Plains today and over the Mississippi Valley on Friday. Our severe weather expert, Dr. Rob Carver, is following the action.
By: JeffMasters, 2:30 PM GMT on April 27, 2010
The devastating tornado that ripped through Mississippi on Saturday April 24, killing ten, was a violent EF-4 twister with 170 mph winds when it hit Yazoo City, according to a preliminary damage survey by the National Weather Service in Jackson, Mississippi. The tornado touched down near Tallulah, Louisiana, crossed the Mississippi River into Mississippi, and traversed nearly the entire state of Mississippi, carving a 149-mile long path of destruction. It is extremely rare for a tornado to stay on the ground this long. The world record longest path by a tornado is the 219-mile long path of the deadliest tornado in U.S. history, the violent F-5 Tri-State Tornado of 1925, which killed 695 people in Missouri, Illinois, and Indiana.
Figure 1. A church in Yazoo City works to restore its toppled steeple after Saturday's tornado. Image credit: J.A.
Saturday's tornado was strong almost from its initial stage of development in northeast Louisiana. EF-2 and EF-3 damage was common all along the tornado's path into central Mississippi with areas of EF-4 damage observed in both Yazoo and Holmes counties. After crossing Interstate 55, the tornado weakened with EF-1 and occasional EF-2 damage being common as the tornado moved across Attala County. The tornado re-intensified as it moved into Choctaw County, with at least high end EF-3 damage occurring northwest of the Weir community. The tornado remained strong before rapidly weakening and then dissipating just after moving into Oktibbeha County. It was the first violent EF-4 tornado of 2010. Over the past decade, the U.S. has averaged five violent EF-4 or EF-5 tornadoes per year. Our severe weather expert, Dr. Rob Carver, has a more detailed analysis of Saturday's tornado.
Figure 2. One mile wide wedge tornado from near Yazoo City, Mississippi on April 24, 2010. Tornadovideos.net intercepted the tornado near Holly Bluff just east of the Mississippi River, and tracked the huge wedge to the damage path in Yazoo City, after which they assisted with the rescue effort until emergency personnel gained control of the situation.
Portlight assesses needs after the Mississippi tornado
Portlight.org volunteer Riki Chomsky (AKA "kitchengypsy") paid a visit to tornado-ravaged Yazoo City, Mississippi on Sunday to assess whether or not Portlight should mount a response effort. Her report:
At this time, Portlight has decided not to deploy an emergency feeding unit to Yazoo City. We base this decision on 3 factors:
1) Scope. Although the scenes of devastation are terrible, by our estimate, more than half the city is relatively unharmed. With several restaurants, gas stations and other services open for business in such close proximity to the command center, we have faith that continuity of operations will soon be established for the whole city.
2) Current efforts: All current relief teams, with special emphasis on the Red Cross and Salvation Army, are doing an excellent job of handling the situation. They have taken pains to ensure food distribution across the affected areas, and we have confidence that they are truly the best organizations for this type of situation.
3) Anticipated Need / Speed of Recovery: although the extent of the damage will most likely require outside work crews, we saw very encouraging signs of progress. Work crews were active at almost every damaged site, which is highly impressive for less than 24 hours after the storm. Even when volunteer crews are brought in, we anticipate their needs being more than adequately met by the existing local churches, who have already started feeding work crews and rescue personnel. In addition to the Red Cross and Salvation Army, Portlight extends our appreciation to all members of this exemplary community response. While the damage is significant, the Salvation Army and local Red Cross seem to be doing a great job meeting the needs there, and Portlight recommends supporting one of these organizations.
Portlight continues aid efforts in Haiti
Portlight continues to focus its energy and funds on the situation in Haiti, where the rainy season is fast approaching the needs for shelter, medical supplies, food and water remain urgent. Their latest effort is a shipment of 10 pallets of Durable Medical Equipment, 30 pallets of water, 7,000 pounds of rice, a number of tents, tarps and various building supplies totaling some 14,000 pounds of goods. The supplies were loaded onto the schooner Halie and Mathew. The schooner was slowed by bad weather on its way to Haiti, and was forced to dock in Jamaica to make repairs. The ship is expected to land in Haiti later this week to deliver its supplies. Please visit the Portlight.org web site or the Portlight blog to learn more and to donate to this worthy cause.
Figure 3. Relief supplies for Haiti earthquake victims being loaded onto the schooner Halie and Mathew.
By: JeffMasters, 1:22 PM GMT on April 25, 2010
A powerful 1/2 to 1-mile wide tornado cut a path of enormous destruction across the state of Mississippi yesterday, killing at least ten and injuring dozens. It was the deadliest tornado in the U.S. since May 10, 2008, when an EF-4 tornado killed 22 people in Oklahoma and Missouri. The damage I've seen so far from photos of yesterday's tornado appears to be mainly of the EF-3 variety, though we will have to wait for the official damage surveys to be sure. The supercell thunderstorm that spawned the tornado or family of tornadoes maintained a continuous circulation from the time the tornado first touched down in Louisiana near the Mississippi border until the tornado reached the Alabama border. This is an extremely rare occurrence. If the 188-mile path of destruction across Mississippi was from a single tornado, it would rank as one of the longest tracks by a single tornado on record. The record of 219 miles is held by the deadliest tornado of all time, the great Tri-State Tornado of 1925 (though there is some dispute over whether this was one tornado or a family of tornadoes.) Our severe weather expert Dr. Rob Carver has a more complete analysis and imagery of yesterday's tornadoes.
Figure 1. Doppler radar storm-relative velocity of the mile-wide tornado that affected Yazoo City, Mississippi On April 24, 2010. This is an unusually wide and strong circulation for a supercell thunderstorm.
More severe weather expected today along the East Coast
The Storm Prediction Center (SPC) outlined a "Slight Risk" region of concern for severe weather today along the East Coast, from Maryland to Northern Florida. Yesterday, SPC had Mississippi underneath the first "High Risk" area of severe weather concern for the year. As usual, you can follow today's severe weather outbreak with our interactive tornado page and our severe weather page..
Figure 2. Severe weather reports for Saturday. Note the long line of red tornado reports extending across the state of Mississippi. These reports originated from a single supercell thunderstorm that spawned one or more tornadoes that carved out a 188-mile lone path of destruction across the state. Image credit: Storm Prediction Center.
By: JeffMasters, 1:41 PM GMT on April 23, 2010
After a record quiet start to the 2010 severe weather season, the atmosphere finally unleashed one of its classic violent spring weather days yesterday. NOAA's Storm Prediction Center tallied 32 tornado reports in Colorado, Kansas, and Texas. Fortunately, most of the storms occurred over uninhabited areas, and no injuries or major damage were reported. Our severe weather expert Dr. Rob Carver, has the details on the action in his blog today. The action was focused in a region the Storm Prediction Center had put in their "Moderate Risk" area for severe weather in yesterday's outlook. This was the first "Moderate Risk" region declared so far this year, which is a record for the latest day in the year this has occurred. According to Rich Thompson, a forecaster at NOAA's Storm Prediction Center, the previous record latest date for a "Moderate Risk" severe weather day was March 21, 2005. So, we beat the previous record by an entire month, which is a remarkable feat. There has been only one tornado death so far this year, the lowest death toll this far into the season on record. Typically, about half of the 80 or so tornado deaths we average per year have occurred by this point in the season. Yesterday's preliminary tornado count of 32 came close matching the preliminary U.S. tornado count for the entire month of March--36. March was the fourth-quietest March for tornado activity since record keeping began in 1950. The three-year average for March tornadoes is 138. One reason for the quiet tornado season has been the "upside down" winter and early spring we've experienced over North America over the past 3 1/2 months. Temperatures in Canada have been the warmest on record during this period, but have been unusually cold over the southern U.S. and Gulf of Mexico. Since the instability that severe thunderstorms need to occur comes from warm, moist air from the Gulf of Mexico encountering cold, dry air from Canada, this year's unusual "upside down" configuration has led to a much more stable than usual atmosphere over tornado alley in the U.S.
Figure 1. Doppler radar storm-relative velocity of the mile-wide tornado that affected western Kansas at 4:40 MDT April 22, 2010. No damage or injuries were reported from the tornado. A second tornado's Doppler radar signature is also visible at the bottom of the image.
Another severe weather outbreak expected today and Saturday
The Storm Prediction Center has outlined another "Moderate Risk" region of concern for severe weather today, this time centered over Arkansas, Mississippi, and northern Louisiana (Figure 2.) Tomorrow, the action moves eastwards and will be centered over Mississippi, Alabama, and Tennessee. This 3-day severe weather event will probably end up being one of the most significant of the year. Our severe weather expert Dr. Rob Carver will blog about today's action after it is over. As usual, you can follow today's severe weather outbreak with our interactive tornado page and our severe weather page..
Figure 2. Severe weather risk areas for Friday April 23, 2010.
Tornado and associated severe weather leave 1 million homeless in India
The U.S. has the world's most violent and numerous tornadoes, but second place goes to Bangladesh and eastern India. There, warm moist air from the Bay of Bengal often encounters cold, dry air from the Himalayas, setting up the instability needed to support severe thunderstorms. On Tuesday, April 13, and very unstable airmass (CAPE values > 3000) with strong westerly wind shear set up over eastern India, providing the classic set-up for supercell thunderstorms. Radar loops from the Kolkatta radar that day show a severe thunderstorm formed over extreme northeast India, near the Bangladesh border, and moved southeast into Bangladesh. The thunderstorm appeared to form a "bow echo", a configuration that often generates strong winds in excess of hurricane force near the bowed-out portion of the radar echo. Winds of 75 mph affected a large area of densely populated land, killing 137, severely damaging or destroying 200,000 homes, and leaving 1 million homeless. A weak tornado may have accompanied the storm. This may be the greatest number of people ever left homeless by a severe thunderstorm in world history.
Figure 3. Radar image from the Kolkatta Regional Meteorological Centre of the Indian Meteorological Department, showing the severe thunderstorm that killed 137 people and left 1 million homeless. Thanks go to Steve Nesbitt of UIUC for saving this image.
By: JeffMasters, 1:26 PM GMT on April 22, 2010
Today is Earth Day, a day to celebrate the beauty of the atmosphere, oceans, and biosphere of the planet that sustains us. As is my tradition on Earth Day, I'll present my five favorite wunderphotos uploaded to our web site over the past year. I want to thank everyone who has participated in making this the best weather photo gallery on the Internet--your photos are truly an inspiration! If you take a great image, I encourage you to upload your photo at higher resolution, so it can be considered for our new Worldview Gallery, updated weekly with the top wunderphotos of the week.
Of special note today is a photo posted by wunderground user Trigirl, who has posted some fantastic wunderphotos over the years. Her wunderphoto of eight young Mennonite women standing in the fog and light rain of the Smoky Mountains was posted on June 9 of last year. She entered the photo in the Smithsonian Magazine's photo contest in the Americana category, and won first prize out of 60,000 entries. Congratulations, Debra!
Figure 1. Eight young Mennonite women stand in the fog and light rain of the Smoky Mountains, on the scenic overlook wall.
Severe weather today for Texas and Oklahoma
The Storm Prediction Center has outlined a "Slight Risk" region of concern for severe weather over Texas, Oklahoma, Kansas, and Colorado today. Tomorrow, the action moves eastwards into the Mississippi Valley, and we could get one of the larger severe weather events of this quiet severe weather season. Our severe weather expert Dr. Rob Carver will blog on the action, if it cranks up.
By: JeffMasters, 12:56 PM GMT on April 21, 2010
The worst is now over for European air traffic disruptions from the ongoing eruption of Iceland's Eyjafjallajökull volcano. The eruptions are currently only throwing ash up to 16,000 feet (4900 meters), according to the latest advisory from the UK Met Office. Lightning images from UK Met Office show no new lightning strikes from the volcano's plume since Sunday. The lower amounts of ash are due, in part, to the fact that the volcano has melted most of the ice and snow covering the crater. This ice had caused the hot magma erupting through it to fragment into fine ash capable of reaching much higher heights of 6 - 11 km (20,000 - 36,000') in the early stages of the eruption. Ash is also reduced because the volcano has entered a phase where it is producing more magma. Although it is possible that the volcano could enter a more explosive eruption phase that would throw ash high into the air once again, the winds are expected to shift over Iceland late this week. The northwest winds that have been "stuck" in place over Iceland over the past week due to a persistent trough of low pressure over northern Europe, will gradually shift to westerly by Friday and southwesterly by Saturday. This means that new eruptive material will blow over the northern British Islands and northern Scandanavia late this week, avoiding the main portion of Europe. Ash should be confined to northern Scandanavia and Greenland through most of next week, since the southwesterly winds are expected to continue through most of next week.
Figure 1. Iceland’s Eyjafjallajökull volcano began to ease out of the ash-producing phase of its eruption and started to emit magma on April 19, 2010, said the Icelandic Met Office. The cloud of ash coming from the volcano was lower than it had been in previous days, rising just 4 to 6 kilometers (2 to 3 miles) into the atmosphere. In this photo-like image, taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite, the ash extends south in a broad brown plume. Smaller plumes extend from the coast east of the primary plume. These are likely re-suspended ash, fine volcanic ash that had settled on the land, but is now being picked up by the wind. The plume blows south and then curves east over the ocean, blending with the outer bands of a low-pressure system. Image credit: NASA.
I'll have a new post Thursday (Earth Day!)
By: JeffMasters, 2:45 PM GMT on April 19, 2010
The eruption of Iceland's volcano with the unpronounceable name, Eyjafjallajökull, has virtually ceased over the past few hours, with ash only reaching up to 6,000 feet (1800 meters), according to the latest advisory from the UK Met Office. Lightning images from UK Met Office show no new lightning strikes from the volcano's plume since midnight local time today. The relatively small amount of ash present at low altitudes will probably not be able to make it all the way to mainland Europe before falling to the surface and dissipating, since 6,000 feet is below the altitude that the strong winds of jet stream blow. Wednesday through Sunday, the volcano emitted a towering cloud of volcanic ash 6 - 11 km (20,000 - 36,000') high in the air from its 1666 meter (5500') high peak. The jet stream blows strongly at that altitude range, which allowed for efficient transport of the ash cloud to mainland Europe.
Figure 1. Lightning lights up the night sky in this photo of Eyjafjallajökull's eruption taken on April 16, 2010. Ash particles colliding together separate electric charge, much as ice particles in a thunderstorm do, leading to spectacular lightning displays. Image credit: Marco, Fulle, Stromboli Online.
Forecasts of the movement of the ash cloud are made using trajectory models, which have a number of uncertainties to consider. Firstly, the amount of ash ejected by the volcano is highly uncertain, since our measurements of this quantity are limited. Secondly, the models must compute how high the ash cloud will rise (plume rise), based on the best available measurements of atmospheric stability. Since upper air-observations are taken just twice daily by a very coarse network of balloon soundings, our knowledge of the stability is rather crude. Finally, the trajectory models use forecast winds from a global model such as the GFS model to predict where the plume may go. The forecast winds from this model do not capture much of the complicated structure of the wind field over Europe, leading to a rather fuzzy approximation of where the ash will go. Nevertheless, these models have in general done a respectable job forecasting where the ash from Eyjafjallajökull will go over the past few days.
Figure 2. Cross section of the atmosphere over time over Paliseau, France, on April 16, 2010, as observed using ground-based lidar. Image taken using a 532nm cross polarization NFOV telescope. Note how the ash layer sinks closer to the ground as time progresses, as gravity makes the ash sink to the ground. There may also be some atmospheric subsidence occurring (downward moving air due to large-scale atmospheric processes.) Image credit: Ray Hoff, World Meteorological Organization's Global Atmosphere Watch's Aerosol Lidar Network (GALION).
For the next few days, these models continue to indicate that northwest winds at the jet stream level will continue to affect Iceland. As a result, Spain, Portugal, and Greece will offer the best locations to fly from. The northwesterly winds are expected to continue for the remainder of the week, thanks to an upper-level trough of low pressure over northern Europe. On Saturday April 24, the ECMWF model predicts that the trough will slide eastwards, and a ridge of high pressure will build over Europe. This will bring upper-level winds out of the southwest to Iceland, directing any volcanic ash northwards over the North Pole. Thus for the remainder of this week, expect continued ash clouds over much of Europe if the volcano resumes significant eruptions. But by next Sunday, the ash over Europe should decline considerably. For the latest one-day forecasts of where the ash cloud is expected to go, consult the UKMET Office. The Rhenish Institute for Environmental Research at the University of Cologne also has some excellent simulations from an atmospheric dispersion model of Eyjafjallajökull's eruption plume. The Norwegian Institute for Air Research runs a computer trajectory model called FLEXPART that has 1-day forecasts showing a cross section of the atmosphere. NOAA's Air Resources Laboratory (ARL) lets you perform your own model run using their HYSPLIT model, going out up to 48 hours, using the GFS model as input.
Figure 3. NASA's Aqua satellite captured this image of the eruption at 1:20 UTC on April 17, 2010. Image credit: NASA Earth Observatory.
An excellent source of links of information on the eruption is available at http://islande2010.mbnet.fr/2010/04/eyjafjallajok ul-links-liens-a-propos-de-leyjafjallajokul/. My post on Thursday discusses the likely non-impact of this eruption on Earth's climate. Finally, we need to be keeping an eye on earthquake activity at the dangerous Katla volcano next to Eyjafjallajökull. If that volcano blows, it could mean dwarf the headaches caused by Eyjafjallajökull.
By: JeffMasters, 2:20 PM GMT on April 16, 2010
The globe recorded its warmest March since record keeping began in 1880, according to the National Oceanic and Atmospheric Administration's (NOAA's) National Climatic Data Center. The March temperature anomaly of 0.77°C (1.39°F) beat the previous record set in 2002 by 0.03°C. The last time the globe had a record warmest month was in January 2007 (according to NOAA) or in November 2009 (according to NASA). NASA's Goddard Institute for Space Studies rated March 2010 the second warmest March on record, 0.01°C behind the record set in 2002. The year-to-date period, January - March, is the 4th warmest such period on record, according to NOAA, and the warmest on record, according to NASA. March 2010 global ocean temperatures were the warmest on record, while land temperatures were the 4th warmest. Global satellite-measured temperatures for the lowest 8 km of the atmosphere were the warmest on record in March, according to both the University of Alabama Huntsville (UAH) and Remote Sensing Systems (RSS) groups. The March temperature anomaly of 0.66°C was the third highest monthly anomaly on record, behind the 0.76°C anomalies measured in February and April of 1998.
For those interested, NCDC has a page of notable weather highlights from March 2010.
Figure 1. Departure of temperature from average for March 2010. Image credit: NOAA National Climatic Data Center.
A warm March for the U.S.
For the contiguous U.S., it was the 32nd warmest March in the 116-year record, according to the National Climatic Data Center. For the third month in a row, Florida was the coldest state, relative to average. It was Florida's 4th coldest March. No other state had a top-ten coldest March. Rhode Island had its warmest March on record, and thirteen other states had a top-ten warmest March, including all of New England, plus Michigan, Wisconsin, Minnesota, and Montana.
U.S. precipitation and drought
For the contiguous U.S., March 2010 ranked as the 35th driest in the 116-year record. Michigan, Wisconsin, and Montana recorded a top-ten driest March. However, all-time March precipitation records were set in Massachusetts, New Jersey, and Rhode Island. New Hampshire and Connecticut each had a top-five wettest March. At the end of March, 2.0% of the contiguous United States was in severe-to-exceptional drought. This is the lowest March drought footprint in the U.S. in the past ten years.
Figure 2. Computer model forecasts of El Niño/La Niña made in April. The forecasts that go above the red line at +0.5°C denote El Niño conditions; -0.5°C to +0.5°C denote neutral conditions, and below -0.5°C denote La Niña conditions. No computer models predict El Niño conditions and six predict La Niña for the upcoming hurricane season (ASO, August-September-October). The rest of the models predict neutral conditions. Image credit: Columbia University's IRI.
El Niño fades from moderate to weak
El Niño slowly weakened during late March and early April, and El Niño conditions crossed the threshold from moderate to weak during the past two weeks. Sea surface temperatures over the tropical Eastern Pacific in the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region", were at 0.83°C above average on April 11, which is just below the 1.0°C threshold to be considered a moderate El Niño, according to the Australian Bureau of Meteorology. Anomalously strong westerly winds along the Equator that had helped maintain the current El Niño slackened in late March, and winds are now near average over the Equatorial Pacific. It now appears very likely that El Niño will be gone by hurricane season. None of the sixteen El Niño models (updated as of April 15) are predicting El Niño will be around during the height of hurricane season (August-September-October); six are predicting La Niña conditions for hurricane season. The expected demise of El Niño, coupled with sea surface temperatures in the tropical Atlantic that are currently at record levels, have prompted two major hurricane forecasting groups (tropicalstormrisk.com and Colorado State University) to predict a well-above average 2010 Atlantic hurricane season.
March sea ice extent in the Arctic 5th lowest on record
March 2010 Northern Hemisphere sea ice extent was the 5th lowest since satellite measurements began in 1979. Ice extent was lower than in 2009 and 2008, but greater than in 2004, 2005, 2006, and 2007, according to the National Snow and Ice Data Center (NSIDC). The weather pattern over the Arctic during much of March 2010 featured a strongly negative Arctic Oscillation (AO). This pattern tends to slow the winds that typically flush large amounts of sea ice out of the Arctic between Greenland and Iceland, and the Arctic lost less ice this winter compared to the previous few years. The larger amount of multi-year ice could help more ice to survive the summer melt season. However, this replenishment consists primarily of younger, two- to three-year-old multi-year ice; the thickest ice more than three years old has continued to decline.
Iceland's Eyjafjallajökull volcano continues to disrupt European air travel
The Eyjafjallajökull volcano on Iceland erupted Wednesday, sending a towering cloud of volcanic ash 6 - 11 km (20,000 - 36,000') high in the air from its 1666 meter (5500') high peak. The ash cloud continues to cause a dramatic interruption of air traffic over much of northern Europe today, and this disruption will spread southwards and eastwards as the ash cloud gradually spreads and disperses. For the latest forecasts of where the ash cloud is expected to go, consult the UKMET Office. The Norwegian Institute for Air Research runs a computer trajectory model called FLEXPART that has longer, 3-day forecasts. The FLEXPART model shows that ash will continue to be a problem for much of Europe through Tuesday. Spain and Portugal look like the best bet to have airports that will stay open. An excellent source of links of information on the eruption is available at http://islande2010.mbnet.fr/2010/04/eyjafjallajok ul-links-liens-a-propos-de-leyjafjallajokul/. My post on Thursday discusses the likely non-impact of this eruption on Earth's climate.
Figure 3. Forecast extent of the plume from the Iceland volcano with the unpronounceable name. Forecast was made at 17 UTC Saturday, April 17, 2010, and is valid for 12 UTC Tuesday, April 20, 2010. Image credit: Norwegian Institute for Air Research.
By: JeffMasters, 2:11 PM GMT on April 15, 2010
The Eyjafjallajökull volcano on Iceland erupted Wednesday, sending a towering cloud of volcanic ash 6 - 11 km (20,000 - 36,000') high in the air from its 1666 meter (5500') high peak. The ash cloud has caused a dramatic interruption of air traffic over much of northern Europe today, and this disruption will spread southwards and eastwards over the next day as the ash cloud gradually spreads and disperses (Figure 2.)
Figure 1. Ash plume from Eyjafjallajokull Volcano over the North Atlantic at 11:35 UTC April 15, 2010. Image credit: NASA.
Figure 2. Forecast extent of the ash cloud from the Eyjafjallajökull volcano on Iceland at 12 UTC (8 am EDT) and 00 UTC tonight (8 pm EDT.) The red colors show the extent between the surface and 20,000', the green colors between 20,000 - 35,000', and the blue line between 35,000 - 55,000'. Commercial jetliners typically cruise at 35,000'. Image credit: UKMET Office.
Iceland volcano not likely to significantly affect the climate or weather
Volcanic eruptions are capable of significantly cooling the climate for 1 - 2 years after a major eruption spews sulfur dioxide gas forcefully enough so that it reaches the stratosphere. Once in the stratosphere, the gas reacts to form highly reflective sulfuric acid droplets mixed with water (sulfate aerosol particles). Our volcanoes and climate page covers the topic in more detail. Let's examine recent volcanic eruptions that have had a significant cooling effect on the climate. In the past 200 years, Mt. Pinatubo in the Philippines (June 1991), El Chichon (Mexico, 1982), Mt. Agung (Indonesia, 1963), Santa Maria (Guatemala, 1902) Krakatoa (Indonesia, 1883), and Tambora (1815) all created noticeable cooling. The Mt. Pinatubo and El Chichon eruptions caused a greater than 10% drop in sunlight reaching the surface. The eruption of Tambora in 1815 had an even greater impact, triggering the famed Year Without a Summer in 1816. You'll notice from the list of eruptions above that all of these climate-cooling events were from volcanoes in the tropics. Above the tropics, the stratosphere's circulation features rising air, which pulls the sulfur-containing volcanic aerosols high into the stratosphere. Upper-level winds in the stratosphere tend to flow from the Equator to the poles, so sulfur aerosols from equatorial eruptions get spread out over both hemispheres. These aerosol particles take a year or two to settle back down to earth, since there is no rain in the stratosphere to help remove them. However, if a major volcanic eruption occurs in the mid-latitudes or polar regions, the circulation of the stratosphere in those regions generally features pole-ward-flowing, sinking air, and the volcanic aerosol particles are not able to penetrate high in the stratosphere or get spread out around the entire globe.
There have been at least two exceptions to the tropics-only rule. Realclimate.org discusses the eruption of the Laki volcano in Iceland, between 1783-1784. The eruption was probably not able to inject much sulfur into the stratosphere. However, since the eruption was sustained for so long, significantly elevated sulfur concentrations were seen in the lower atmosphere over much of the Atlantic and European regions, which had a pronounced cooling effect on the region.
scienceblog.com has an interesting article about the largest volcanic eruption of the 20th century--the 1912 eruption of Alaska's Mt. Novarupta, located in the same chain of volcanoes as Mt. Redoubt. According to a NASA computer model, Novarupta's climate-cooling aerosols stayed north of 30°N latitude, and did not cause global cooling. However, the model indicates that the eruption may have indirectly weakened India's summer monsoon, producing an abnormally warm and dry summer over northern India.
It does not appear that the current eruption of the Eyjafjallajökull volcano on Iceland was large enough to alter the atmospheric circulation of the Northern Hemisphere and cause a change in the late spring/early summer weather patterns. A series of several major eruptions over the next few weeks would be required for that to happen. The volcano is also too far north for the cooling effect of its ash cloud to affect the sea surface temperatures in the tropical Atlantic for the coming hurricane season. However, the ash could should bring spectacular sunsets to Europe over the next week, and to North America by sometime next week, as the jet stream wraps the ash cloud eastwards across the Northern Hemisphere.
Portlight aid ship nears Haiti
Portlight.org continues to work hard to get food and medical supplies into the earthquake zone in Haiti. Their latest effort is a shipment of 30,000 pounds of rice and 20,000 pounds of other supplies, mostly medical equipment, that has been loaded onto the schooner Halie and Mathew. The schooner is expected to land in Haiti today to deliver the supplies. Please visit the Portlight.org web site or the Portlight blog to learn more and to donate to this worthy cause.
Figure 2. Relief supplies for Haiti earthquake victims being loaded onto the schooner Halie and Mathew.
Paul Timmons (Presslord) and Pat Pearson (Patrap) of Portlight will on the Internet radio show, the Daily Downpour Link. The hosts are wunderground meteorologists Shaun Tanner and Tim Roche. The show airs today, Thursday, April 15, at 4pm Eastern.
By: JeffMasters, 2:42 PM GMT on April 12, 2010
Sea Surface Temperatures (SSTs) in the Atlantic's Main Development Region for hurricanes had their warmest March on record, according to an analysis of historical SST data from the UK Hadley Center. SST data goes back to 1850, though there is much missing data before 1910 and during WWI and WWII. The region between 10°N and 20°N, between the coast of Africa and Central America (20°W - 80°W), is called the Main Development Region (MDR) because virtually all African waves originate in this region. These African waves account for 85% of all Atlantic major hurricanes and 60% of all named storms. When SSTs in the MDR are much above average during hurricane season, a very active season typically results (if there is no El Niño event present.) SSTs in the Main Development Region (10°N to 20°N and 20°W to 85°W) were an eye-opening 1.26°C above average during March. This easily beats the previous record of 1.06°C set in 1969. SSTs in the Main Development Region are already warmer than they were during late June of last year, which is pretty remarkable, considering that March is one of the coldest months of the year for SSTs in the North Atlantic. Last month's anomaly of 1.26°C tied with June 2005 as the greatest monthly anomaly ever recorded in the Atlantic MDR.
Figure 1. The departure of sea surface temperature (SST) from average for April 12, 2010. Image credit: NOAA/NESDIS.
What is responsible for the high SSTs?
As I explained in detail in last month's post on record February SSTs in the Atlantic, the Arctic Oscillation (AO) and its close cousin, the North Atlantic Oscillation (NAO), are largely to blame for the record SSTs. The AO and NAO are climate patterns in the North Atlantic Ocean related to fluctuations in the difference of sea-level pressure between the Icelandic Low and the Azores-Bermuda High. If the difference in sea-level pressure between Iceland and the Azores is small (negative NAO), this creates a weak Azores-Bermuda High, which reduces the trade winds circulating around the High. During December - February, we had the most negative AO/NAO since records began in 1950, and this caused trade winds between Africa and the Lesser Antilles Islands in the hurricane Main Development Region to slow to 1 - 2 m/s (2.2 - 4.5 mph) below average. Slower trade winds mean less mixing of the surface waters with cooler waters down deep, plus less evaporational cooling of the surface water. As a result, the ocean heated up significantly, relative to normal, over the winter. This heating is superimposed on the very warm global SSTs we've been seeing over the past few decades due to global warming. Global and Northern Hemisphere SSTs were the 2nd warmest on record this past December, January, and February. We are also in the warm phase of a decades-long natural oscillation in Atlantic ocean temperatures called the Atlantic Multi-decadal Oscillation (AMO). This warm phase began in 1995, and has been partially responsible for the high levels of hurricane activity we've seen since 1995.
What does this imply for the coming hurricane season?
The high March SST anomaly does not bode well for the coming hurricane season. The three past seasons with record warm March SST anomalies all had abnormally high numbers of intense hurricanes. Past hurricane seasons that had high March SST anomalies include 1969 (1.06°C anomaly), 2005 (0.93°C anomaly), and 1958 (0.93°C anomaly). These three years had 5, 7, and 5 intense hurricanes, respectively. Just two intense hurricanes occur in an average year. The total averaged activity for the three seasons was 15 named storms, 11 hurricanes, and 6 intense hurricanes (an average hurricane season has 10, 6, and 2.) Both 1958 and 2005 saw neutral El Niño conditions, while 1969 had a weak El Niño. So, even if this year's El Niño lingers on into hurricane season, it may not protect us from a hyper-active hurricane season--the weak El Niño year of 1969 had 18 named storms, 12 hurricanes, and 5 intense hurricanes.
April forecast for the 2010 Atlantic hurricane season issued by Colorado State University
A well above-average Atlantic hurricane season is on tap for 2010, according to the latest seasonal forecast issued last week by Dr. Phil Klotzbach and Dr. Bill Gray of Colorado State University (CSU). The Klotzbach/Gray team is calling for 15 named storms, 8 hurricanes, and 4 intense hurricanes. An average season has 10 named storms, 6 hurricanes, and 2 intense hurricanes. The forecast calls for 30% above-average chance of a major hurricane hitting the U.S., both along the East Coast (45% chance, 31% chance is average) and the Gulf Coast (44% chance, 30% chance is average). The Caribbean is also forecast to have an above-average risk of a major hurricane (58%, 42% chance is average.)
The forecasters cited two main reasons for their forecast of an active season:
1) Sea surface temperature (SST) anomalies in the tropical Atlantic are at their warmest levels on record in the Main Development Region for hurricanes in the tropical Atlantic. Warmer-than-normal waters provide more heat energy for developing hurricanes. In addition, an anomalously warm tropical Atlantic is typically associated with lower sea level pressure values and weaker-than-normal trade winds, indicating a more unstable atmosphere with decreased levels of vertical wind shear, favoring hurricane development. Part of the reason for the substantial warming is because a weaker than average Bermuda-Azores High drove weak trade winds over the winter and early spring. These weaker winds acted to reduce evaporative cooling of the ocean. Weaker winds also decreased the mixing of cool waters to the surface from below.
2) Hurricane activity in the Atlantic is lowest during El Niño years and highest during La Niña or neutral years. The CSU team expects the current weak to moderate El Niño conditions to transition to neutral and perhaps weak La Niña conditions by this year's hurricane season. April and May are typically the months when the atmosphere will swing between El Niño and La Niña, which makes any seasonal forecasts of hurricane activity during April low-skill. The current computer models used to predict El Niño (Figure 2) mostly favor neutral conditions for the coming hurricane season. The models used include statistical models, which observe how previous El Niño events have evolved, and sophisticated computer-intensive dynamical models (similar to the GFS model we use to make weather forecasts). The reliability of all of these models is poor, but the CSU team believes the ECMWF model (yellow-orange squares) is the best one. The ECMWF model only goes out to JJA (June-July-August) in this plot, and is forecasting neutral conditions.
Figure 2. Computer model forecasts of El Niño/La Niña made in March. The forecasts that go above the red line at +0.5°C denote El Niño conditions; -0.5°C to +0.5°C denote neutral conditions, and below -0.5°C denote La Niña conditions. Three computer models predict El Niño conditions and three predict La Niña for the upcoming hurricane season (ASO, August-September-October). However, most of the models predict neutral conditions. Image credit: Columbia University's IRI.
The CSU team picked five previous years when atmospheric and oceanic conditions were similar in April to what we are seeing this year. Those five years were 2005, the most active Atlantic season in history; 1998, which had Category 5 Hurricane Mitch in the Western Caribbean; 1969, which featured Category 5 Hurricane Camille, the strongest hurricane ever to hit the U.S.; 1966, which had Category 4 Hurricane Inez that killed 1,000 people in the Caribbean and Mexico; and 1958, which had five major hurricanes. The mean activity for these five years was 16 named storms, 10 hurricanes, and 5 intense hurricanes.
How accurate are the April forecasts?
While the formulas used by CSU do well in making hindcasts--correctly modeling the behavior of past hurricane seasons--their April hurricane season forecasts have no skill in predicting the future. This year's April forecast uses the same formula as was used in 2008 and 2009. This scheme successfully predicted an active hurricane season in 2008, but failed to properly predict the relatively quiet 2009 hurricane season. A different formula was used prior to 2008, and the April forecasts using that formula showed no skill over a simple forecast using climatology. CSU maintains an Excel spreadsheet of their forecast errors (expressed as a mathematical correlation coefficient, where positive means a skilled forecast, and negative means they did worse than climatology) for their their April forecasts. For now, these April forecasts should simply be viewed as an interesting research effort that has the potential to make skillful forecasts. The next CSU forecast, due on June 2, is the one worth paying attention to. Their early June forecasts have shown considerable skill over the years.
2010 Atlantic hurricane season forecast from Tropical Storm Risk, Inc.
The British private forecasting firm Tropical Storm Risk, Inc. (TSR), issued their 2010 Atlantic hurricane season forecast last week, and they are also calling for a very active year: 16.3 named storms, 8.5 hurricanes, and 4.0 intense hurricanes. TSR predicts a 74% chance of an above-average hurricane season, 20% chance of a near-normal season, and only a 6% chance of a below normal season. They give a 77% chance that 2010 will rank in the top third of most active hurricane seasons on record.
Like the CSU April forecasts, the TSR April forecasts have little skill. I like how TSR puts their skill level right next to the forecast numbers: 12% skill above chance at forecasting the number of named storms, 7% skill for hurricanes, and 6% skill for intense hurricanes. That's not much better than flipping a coin.
TSR projects that 5.1 named storms will hit the U.S., with 2.3 of these being hurricanes. The averages from the 1950 - 2009 climatology are 3.2 named storms and 1.5 hurricanes. Their skill in making these April forecasts for U.S. landfalls is 9 - 13% above chance. In the Lesser Antilles Islands of the Caribbean, TSR projects 1.6 named storms, 0.7 of these being hurricanes. Climatology is 1.1 named storms and 0.5 hurricanes.
TSR cites two main factors for their forecast of an active season: they predict slower than normal trade winds from July - September over the Main Development Region (MDR) for hurricanes over the Atlantic (the region between 10° - 20° N from Central America to Africa, including all of the Caribbean). Trade winds are forecast to be 0.81 meters per second (about 2 mph) slower than average in this region, which would create greater spin for developing storms, and allow the oceans to heat up due to reduced evaporational cooling and reduced mixing of cooler sub-surface waters to the surface. TSR forecasts that SSTs will be 0.42°C above average in the MDR during hurricane season.
Figure 3. Accuracy of long-range forecasts of Atlantic hurricane season activity performed by Phil Klotzbach and Bill Gray of Colorado State University (colored squares) and TSR (colored lines). The CSU team's April forecast skill is not plotted, but is less than zero. The skill is measured by the Mean Square Skill Score (MSSS), which looks at the error and squares it, then compares the percent improvement the forecast has over a climatological forecast of 10 named storms, 6 hurricanes, and 2 intense hurricanes. TS=Tropical Storms, H=Hurricanes, IH=Intense Hurricanes, ACE=Accumulated Cyclone Energy, NTC=Net Tropical Cyclone Activity. Image credit: TSR.
I'll have a new post by Thursday.
By: JeffMasters, 4:06 PM GMT on April 10, 2010
Always obey your air traffic controllers. That's the cardinal rule of of aviation, and one apparently violated by the pilot of the aircraft carrying the Polish president and dozens of the country's top political and military leaders, which crashed in heavy fog this morning near Smolensk, Russia. All 96 people aboard perished. According to the New York Times, air traffic controllers had recommended the president's jet land in nearby Minsk because of bad visibility, but the crew decided to land anyway. The Polish news channel TVN24 reported that moments before the crash, air traffic controllers had refused a Russian military aircraft permission to land, but that they could not refuse permission to the Polish plane. Russian media reported that the airplane's crew made several attempts to land before a wing hit the treetops and the plane crashed about half a mile from the runway.
Figure 1. a large patch of fog covers the Russian city of Smolensk and regions to the east in this visible light image captured by NASA's Terra satellite between 08:00 - 11:15 UTC Saturday, April 10, 2010. Image credit: NASA MODIS Rapid Response System, visualized using Google Earth.
At 10 am local time, near the time of the crash, the Smolensk airport reported heavy fog with visibility 0.5 km (3/10 of a mile). As seen in the satellite image taken near this time (Figure 1), a large bank of fog covered Smolensk and neighboring regions of Russia and Belarus.
By: JeffMasters, 5:06 PM GMT on April 09, 2010
The world's deadliest and most expensive weather disaster so far this year hit Brazil this week, where at least 183 people are dead due to flooding and mudslides in the Rio de Janeiro region. Damage from the flooding has been estimated at 23.76 billion reais (US$13.3bn, €9.9bn), about 8% of the gross domestic product (GDP) of Rio de Janeiro State. Rio's heavy rains began near 5 pm local time (2000 UTC) on Monday April 5, and continued for 24 hours, with a total of 28.8 cm (11.5") of rain falling--more than the average rainfall for the entire month of April. It was the heaviest rainfall ever recorded in Brazil's 2nd largest city. The rains triggered devastating mudslides that roared through slums built on steep, unstable hillsides. According to the Associated Press, crews have pulled 17 bodies from the debris so far at at a new mudslide that hit in Niteroi, next to Rio, on April 7. Authorities fear an additional 150 people may have died there.
Figure 1. Flooding from this week's record rains in Rio de Janeiro. Image credit: Carolina Goncalves / Agência Brasil.
Figure 2. A mudslide in Niteroi, next to Rio de Janeiro, is feared to have killed 200 people. Image credit: Vitor Abdala / Agência Brasil.
The previous deadliest weather disaster this year was the snow avalanche in Afghanistan that killed 172 people on February 8 and 9.
The next post will be Monday.
By: JeffMasters, 1:37 PM GMT on April 05, 2010
Could global warming increase wind shear over the Atlantic, potentially leading to a decrease in the frequency of Atlantic hurricanes? There is a growing consensus among hurricane scientists that this is indeed quite possible. Two recent studies, by Zhao et al. (2009), "Simulations of Global Hurricane Climatology, Interannual Variability, and Response to Global Warming Using a 50-km Resolution GCM", and by Knutson et al. (2008), "Simulated reduction in Atlantic hurricane frequency under twenty-first-century warming conditions", found that global warming might increase wind shear over the Atlantic by the end of the century, resulting in a decrease in the number of Atlantic hurricanes. For example, the second study took 18 relatively coarse (>60 km grid size) models used to formulate the 2007 IPCC climate report, and "downscaled" them using a higher-resolution (18 km grid size) model called ZETAC that was able to successfully simulate the frequencies of hurricanes over the past 50 years. When the 18 km ZETAC model was driven using the climate conditions we expect in 2100, as output by the 18 IPCC models, the authors found that a reduction of Atlantic tropical storms by 27% and hurricanes by 18% by the end of the century resulted. An important reason that their model predicted a decrease in the frequency of Atlantic hurricanes was due to a predicted increase in wind shear. As I explain in my wind shear tutorial, a large change of wind speed with height over a hurricane creates a shearing force that tends to tear the storm apart. The amount of wind shear is critical in determining whether a hurricane can form or survive.
Figure 1. Top: predicted change by 2100 in wind shear (in meters per second per degree C of warming--multiply by two to get mph) as predicted by summing the predictions of 18 climate models. Bottom: The number of models that predict the effect shown in the top image. The dots show the locations where tropical storms formed between 1981-2005. The box indicates a region of frequent hurricane formation where wind shear is not predicted to change much. Image credit: Geophysical Research Letters, "Increased Tropical Atlantic Wind Shear in Model Projections of Global Warming", by Vecchi and Soden, 2007.
Since the Knutson et al. study using the 18 km resolution ZETAC model was not detailed enough to look at what might happen to major Category 3 and stronger hurricanes, a new study using a higher resolution model was needed. This was done by a team of modelers led by Dr. Morris Bender of NOAA's GFDL laboratory, who published their results in Science in February. The authors used the GFDL hurricane model--the model that has been our best-performing operation hurricane track forecasting model over the past five years--to perform their study. The GFDL hurricane model runs at a resolution of 9 km, which is detailed enough to make accurate simulations of major hurricanes. The researchers did a double downscaling study, where they first took the forecast atmospheric and oceanic conditions at generated by the coarse (>60 km grid) IPCC models, used these data to initialize the finer resolution 18 km ZETAC model, then used the output from the ZETAC model to initialize the high-resolution GFDL hurricane model. The final results of this "double downscaling" study suggest that although the total number of hurricanes is expected to decrease by the end of the century, we should expect an increase of 81% in the number of Category 4 and 5 storms in the Atlantic. This trend should not be clearly detectable until about 60 years from now, given a scenario in which CO2 doubles by 2100. The authors say that their model predicts that there should already have been a 20% increase in the number of Category 4 and 5 storms since the 1940s, given the approximate 0.5°C warming of the tropical Atlantic during that period. This trend is too small to be detectable, given the high natural variability and the difficulty we've had accurately measuring the exact strength of intense hurricanes before the 1980s.The region of the Atlantic expected to see the greatest increase in Category 4 and 5 storms by the year 2100 is over the Bahama Islands (Figure 2), since wind shear is not expected to increase in this region, and sea surface temperatures and atmospheric instability are expected to increase there.
The net effect of a decrease in total number of hurricanes but an increase in the strongest hurricanes should cause an increase in U.S. hurricane damages of about 30% by the end of the century, the authors compute, assuming that hurricane damages behave as they did during the past century. Over the past century, Category 4 and 5 hurricanes made up only 6% of all U.S. landfalls, but accounted for 48% of all U.S. damage (if normalized to account for increases in U.S. population and wealth, Pielke et al., 2008.)
Figure 2. Expected change in Atlantic Category 4 and 5 hurricanes per decade expected by the year 2100, according to the Science paper by Bender et al. (2010).
These results seem reasonable, since the models in question have been successfully been able to simulate the behavior of hurricanes over the past 50 years. However, the uncertainties are high and lot more research needs to be done before we can be confident of the results. Not all of the IPCC models predict an increase in wind shear over the tropical Atlantic by 2100, so the increase in Category 4 and 5 hurricanes could be much greater. Also, the GFDL model was observed to under-predict the strength of intense hurricanes in the current climate, so it may not be creating enough Category 4 and 5 hurricanes in the future climate of 2100. On the other hand, IPCC models such as the UKMO-HadCM3 predict a very large increase in wind shear, leading to a drastic reduction in all hurricanes in the Atlantic by 2100, including Category 4 and 5 storms. So Category 4 and 5 hurricane frequency could easily be much greater or much less than the 81% increase by 2100 found by Bender et al.
The estimates of a 30% increase in hurricane damages by 2100 may be considerably too low, since this estimate assumes that sea level rise will continue at the same pace as was observed in the 20th century. Sea level rise has accelerated since the 1990s, and it is likely that this century we will see much more than than the 7 inches of global sea level rise that was observed last century. Higher sea level rise rates will sharply increase the damages due to storm surge, which account for a large amount of the damage from intense Category 4 and 5 hurricanes.
Keep in mind that while a 30% in hurricane damage by the end of the century is significant, this will not be the main reason hurricane damages will increase this century. Hurricane damages are currently doubling every ten years, according to Pielke et al., 2008. This is primarily due to the increasing population along the coast and increased wealth of the population. The authors theorize that the Great Miami Hurricane of 1926, a Category 4 monster that made a direct hit on Miami Beach, would have caused about $150 billion in damage had it hit in 2005. By 2015, the authors expect the same hurricane would do $300 billion in damage. This number would increase to $600 billion by 2025 (though I think it is likely that the recent recession may delay this damage total a few years into the future.) It is essential that we limit coastal development in vulnerable coastal areas, particularly along barrier islands, to reduce some of the astronomical price tags hurricanes are going to be causing. Adoption and enforcement of strict building standards is also a must.
The authors of the GFDL hurricane model study have put together a nice web page with links to the paper and some detailed non-technical explanations of the paper.
Bender et al., 2010, "Modeled Impact of Anthropogenic Warming on the Frequency of Intense Atlantic Hurricanes", Science, 22 January 2010: Vol. 327. no. 5964, pp. 454 - 458 DOI: 10.1126/science.1180568.
Vecchi, G.A., B.J. Soden, A.T. Wittenberg, I.M. Held, A. Leetmaa, and M.J. Harrison, 2006, "Weakening of tropical Pacific atmospheric circulation due to anthropogenic forcing", Nature, 441(7089), 73-76.
Vecchi, G.A., and B.J. Soden, 2007, "Increased Tropical Atlantic Wind Shear in Model Projections of Global Warming", Geophysical Research Letters, 34, L08702, doi:10.1029/2006GL028905, 2007.
By: JeffMasters, 4:04 PM GMT on April 02, 2010
The flood waters have receded in Rhode Island and surrounding regions of New England, leaving hundreds of millions of dollars in damage, but no flood-related deaths. The floods were caused by the third in a series of three extraordinarily wet Nor'easters that drenched the region with record rains over the past month. It was the wettest March on record over most of coastal New England from New York City to Boston, and the wettest month of any kind for several stations, including Providence, Rhode Island, and Blue Hill Observatory, Massachusetts. The rainfall amounts and resulting flooding in many cases exceeded the records set 55 years ago, during the notorious double-punch hurricanes of August 1955, when hurricanes Connie and Diane hit New England within five days of each other. However, this year's flooding event pales in comparison to the 1955 event, when considering damage and death toll. Hurricane Connie killed 25 people, and Hurricane Diane killed nearly 200 people when its record rains drenched regions already in flood because of Hurricane Connie. The single deadliest event occurred when a creek near Stroudsburg, Pennsylvania overflowed, killing fifty people unable to escape the rising water. Diane was the costliest hurricane in U.S. history, until it was surpassed by Hurricane Betsy in 1965. Accounting for inflation, Diane was the 16th costliest hurricane in U.S. history, with total damages of $7 billion (2004 USD.)
Figure 1. Total rainfall from hurricanes Connie and Diane in 1995. Image credit: NOAA.
Figure 2. Observed precipitation for the month of March 2010. Image credit: NOAA.
Severe weather today for Texas, Arkansas, and surrounding states
NOAA's Storm Prediction Center has designated portions of Texas and surrounding states as being at "slight" risk of severe weather today, as a strong springtime storm sweeps through the region. Check out the blog of our severe weather expert, Dr. Rob Carver, to get the details of this potential severe weather episode, which may bring damaging winds, hail, and possible tornadoes to the Dallas/Fort Worth metroplex this afternoon.
Portlight shipping 30,000 pounds of rice to Haiti
Portlight.org continues to work hard to get food and medical supplies into the earthquake zone in Haiti. Their latest effort is a shipment of 30,000 pounds of rice and 20,000 pounds of other supplies, mostly medical equipment, that has been loaded onto the schooner Halie and Mathew. The schooner is laying in Miami, fully loaded, waiting for a decrease in the easterly trade winds. These trade winds will blow at 10 - 20 knots over the next few days, thanks to the clockwise circulation of air around a high pressure system located just east of the Florida coast. According to the latest run of the GFS model, as visualized using our wundermap with the model map layer turned on, the high will slowly move eastward over the next week, and the easterly trade winds will finally die down by Thursday, allowing the Halie and Mathew to set sail for Hispaniola. Please visit the Portlight.org web site to learn more and to donate to this worthy cause.
Figure 3. Some of the 30,000 pounds of rice that has been loaded onto the schooner Halie and Mathew.
By: JeffMasters, 12:49 PM GMT on April 01, 2010
Global warming has unthawed an entire race of warrior mermen and mermaids in the Arctic, scientists revealed today. At a packed press conference in Boulder, Colorado, Dr. Mark Xyzzy of the National Institute for Cryosphere Exploration and Tertiary Research on Yetis (NICETRY) revealed the details of the discovery: "We've been operating robot research submarines under the sea ice in the Chukchi Sea north of Barrow, Alaska this winter, as part of International Geophysical Year studies on the dynamics of arctic sea ice loss," commented Dr. Xyzzy. "Last week, one of our submersibles caught a remarkable video of a warrior mermaid, armed with a trident, riding past the submarine on the back of a narwhal. We were able to track the mermaid to her home--an underwater merfolk city at the bottom of the Chukchi Sea. The city had been thawed out in 2005 by warm water currents invading the Arctic due to global warming. These mermaids and mermen had been frozen into the underwater permafrost since the onset of the last ice age, 115,000 years ago. We undertook immediate efforts to establish communications with the merfolk, by sending in divers with underwater writing boards who were able to work out a simple symbol-based language. We learned that the Chukchi Sea merfolk are at war with a tribe of rival merfolk in the Greenland Sea. The two tribes have been fighting a heated underwater battle for dominance of the Arctic Ocean ever since global warming thawed out both tribes in 2005. It is the explosions from their undersea battles that have been the dominant cause of arctic sea ice loss since 2005, not global warming, as had been previously assumed. A team of experienced United Nations negotiators is now in the Arctic, attempting to broker a truce between the rivals and save the arctic sea ice from further destruction."
Figure 1. Merfolk negotiator Urgok Nzgradborkan and an exhausted U.N. diplomat take a break after a grueling all-night round of peace talks.
Critics of climate change science immediately pounced upon the news to unleash a new barrage of criticism against the National Intergovernmental and Territorial Panel to Investigate Climate Change (NITPICC). "The computer climate models used by the NITPICC utterly failed to anticipate the record loss of arctic sea ice due to underwater explosions from merfolk battles," commented spokesman Markoff Chaney of the Very Competitive Free Enterprise Institute. The Institute maintains of staff of top-notch scientists who swear that their funding from the fossil fuel industry does not affect the objectivity of their science. "This new "mermaid-gate" scandal proves that we can't trust climate models to say diddly-squat that's right about global warming, nah-nah-na-nah-nah!" taunted Chaney.
The head of NITPICC, Dr. R. J. Donteventrytopronouncemylastname, conceded that his organization had some work to do. "We're working very hard to incorporate the effect of underwater explosions from merfolk sea battles into the NITPICC models," said Dr. Donteventrytopronouncemylastname. "We've also begun to explore the impacts on sea ice should other denizens of the Arctic unthaw. For instance, the possibility exists that plesiosaurs from the time of the dinosaurs may be frozen in the underwater arctic permafrost. Should global warming thaw out these great leviathans of the deep, the turbulence from their swimming motions could cause significant cracking and breakup of the sea ice. We now have a new plesiosaur parameterization module built into our top models to account for this possibility."
Dr. Xyzzy of NICETRY commented, "I applaud NITPICC's efforts to incorporate their Underwater Merfolk Battle Module and Plesiosaur Parameterization Module into the climate models. However, I caution that they might also need to build modules to simulate the effects of astrology, thermography, ice-nine, and the warming effect of hot air coming out of Washington politicians, before critics of the NITPICC models will be satisfied."
Internet radio appearance today
I'll be appearing with San Francisco-based wunderground meteorologists Shaun Tanner and Tim Roche on The Daily Downpour Internet radio show at 4:20 pm EDT today, to talk about weather, hurricanes, and climate change. There will not be the opportunity to call in today. No foolin'!
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.
Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather