Category 6™

Winston's Damage Highest in South Pacific History; Extreme February Warmth in Eurasia

By: Jeff Masters and Bob Henson , 3:19 PM GMT on February 29, 2016

The nation of Fiji is struggling to recover from the staggering blow Tropical Cyclone Winston delivered on February 20 when the mighty storm made landfall at Category 5 strength on multiple islands. The storm killed at least 42 people, making it the deadliest in Fiji history. Fiji's previous deadliest storm was Category 3 Cyclone Eric of 1985, which made a direct hit on the capital of Suva, killing 25. Cyclones rarely take many lives across the South Pacific, but the modest population of South Pacific islands means that even a relatively small death toll can have a major impact. Fortunately, Winston's human toll was not as large as it could have been. Several South Pacific cyclones since 1980 are known to have taken more lives than the confirmed total from Winston. The deadliest appears to be Cyclone Namu, which killed at least 150 people during its prolonged trek across the Solomon Islands in May 1986. Thanks to WU member skycycle for bringing other South Pacific cyclone tolls to our attention.


Figure 1. VIIRS infrared image of Tropical Cyclone Winston at 0057 UTC February 20, 2016. At the time, Winston was the strongest storm ever recorded in the Southern Hemisphere, with sustained winds of 185 mph. Koro Island (see damage photo below) is in the eye. Image credit: NOAA/NESDIS.


Figure 2. An example of how Category 5 winds can completely flatten human-built structures: Koro Island received a direct hit from Winston when the storm was at peak strength with 185 mph winds. Image credit: My Fijian Images and Jah Ray.

Winston the most destructive cyclone in South Pacific history
While many cyclones in the South Pacific have caused severe devastation, the roughly half-billion-dollar cost of Winston appears to be a record-setter for this region. Thousands of homes and businesses were destroyed by Winston, with northern and western regions of Fiji receiving catastrophic damage. The government of Fiji estimated on Thursday that the cost of the disaster would be at least $468 million, making it the costliest tropical cyclone in South Pacific history. The previous most costly cyclone in the South Pacific was just last year, when Category 5 Tropical Cyclone Pam tore through Vanuatu, causing $360 million in damage. According to insurance broker Aon Benfield, the previous costliest cyclone in Fiji was Tropical Cyclone Kina in January 1993, at $182 million (2016 USD) in damage. The next-highest damage total was from Cyclone Heta (2003), which inflicted about $150 million in damage (in 2004 US dollars) to American Samoa as well as Niue and Tonga. Fiji's Tropical Cyclone Evan of December 2012 was similar in cost, with damages estimated at $150 million (2016 USD).

Winston's damage is roughly 10% of Fiji's GDP--the type of economic blow that will take many years to recover from. To put this into a U.S. perspective, if the U.S. had a 10% hit to its GDP, that would be a roughly $1.7 trillion disaster, on par with 15 simultaneous Hurricane Katrinas. Unfortunately, insurance penetration in Fiji is only about 2%, making it difficult for people who lost everything to get back on their feet. At least 55,000 people--about 6% of Fiji's population--are in evacuation shelters. Most of the nation's resorts and tourist facilities have reopened, though, and tourism represents about 17% of Fiji's GDP. Another good sign of normalcy returning: schools opened today for the first time since the disaster.


Figure 3. Australian and New Zealand Defense Forces unload relief supplies on February 24, 2016 in Fiji to assist in Tropical Cyclone Winston relief. Image credit: Government of Fiji. Charities asking for donations for Fji cyclone relief include UNICEF, the Australian Red Cross, and Save the Children.


Video 1. The eyewall and eye of Tropical Cyclone Winston, as experienced by a volunteer for Think Pacific working to deliver a youth and sports program for rural school children in the village of Tuatua on Koro, Fiji.

Unprecedented February warmth in Eurasia
December 2015 and January 2016 were Earth's warmest months in recorded history (expressed as the departure of temperature from average), and record-smashing heat in February is making this month a threat to join the parade. Two northward extensions of subtropical heat--one in eastern Europe and one in central Asia--led to phenomenally mild temperatures for February in the last two weeks. At least a dozen countries set or tied their all-time records for February during the latter half of the month, according to international weather records researcher Maximiliano Herrera:



Serbia, 26.6°C (79.9°F) at Knjazevac on Feb. 15
Montenegro, 27.8°C (82.0°F) at Ulcinj on Feb. 16
Romania, 26.0°C (78.8°F) at Patarlagele on Feb. 16 (tied record)
Turkey, 32.4°C (90.3°F) at Milas on Feb. 16
Albania, 28.6°C (83.5°F) at Qyteli Stalin on Feb. 16
Austria, 23.2°C (73.8°F) at Pottschach on Feb. 22 (tied record)
Slovakia, 20.3°C (68.5°F) at Bratislava Airport on Feb. 22
Uzbekistan, 30.1°C (86.2°F) at Termez on Feb. 25
Tajikistan, 29.7°C (85.5°F) at Isambaj on Feb. 25
Kyrgyzstan, 25.8°C (78.4°F) at Dzhalalabad on Feb. 25
Kazakhstan, 26.9°C (80.4°F) at Ciili on Feb. 25
Russia, 24.5°C (76.1°F) at Goriatchi Klioutch on Feb. 27
 
Not to be totally outdone, the midsection of North America had an impressively mild weekend, with temperatures between 55°F and 60°F setting daily records across southern Canada from Edmonton to Toronto. Top pick among the U.S. records: Bismarck, ND, where the 73°F high notched on Saturday was the state’s warmest for the entire month of February in 126 years of record-keeping, a full 41°F above Bismarck’s average high for the date of 32°F. Thanks to WU weather historian Chris Burt for catching this noteworthy statistic. Monthly record highs were also set in Mobridge, SD (73°F) and St. Cloud, MN (58°F), as noted by weather.com.
 
Happy Leap Day, everyone!


Jeff Masters and Bob Henson

Hurricane Heat

Tornado Researchers Head to Alabama for VORTEX Southeast

By: Bob Henson , 4:50 PM GMT on February 26, 2016

The venerable series of studies known as VORTEX is about to enter its third chapter in 22 years, this time with a change in venue. VORTEX Southeast gets an official kick-off with a media day on February 29 in Huntsville, Alabama, the experiment’s home base. As its name implies, VORTEX-SE is focused on the southeastern U.S., where tornadoes can ravage the heavily forested, densely populated landscape at just about any time of year--including February, as highlighted in this week’s deadly outbreak on Tuesday and Wednesday.

VORTEX-SE is targeting a relatively small area in its first field phase this March and April, relying more on fixed instruments and radiosondes (weather balloons) than on the mobile radars that crisscrossed the southern Great Plains during the earlier experiments. The new project also has a beefed-up social science component: investigators will be looking closely at how meteorologists present information about tornadic threats, and how people use and interpret that information.
 

Figure 1. Photographed here in southeast Mississippi, this violent tornado raged across more than 122 miles of Mississippi and Alabama during the Super Outbreak of April 27, 2011. Rated an EF4, it killed seven people. Image credit: NWS/Jackson, MS.
 
Rolling through a different alley
The original VORTEX project (Verification of the Origins of Rotation in Tornadoes, 1994-95) was a landmark in many ways. It was the first major use of the NSF-supported Doppler on Wheels mobile radars, which have become mainstays of weather research. Data from the first VORTEX and its successor, VORTEX2 (2009-10), helped lead to a much more detailed and nuanced picture of how supercell thunderstorms gather and organize rotational energy (vorticity) and why only a small number of supercells manage to parlay their energy into making tornadoes.
 
The southern-Plains focus of the first two VORTEX projects emerged naturally, given that supercell tornadoes are more frequent and often more violent across this region than anywhere else on Earth. But deadly tornadoes also plague other parts of the nation. Geographer Michael Frates outlined four distinct tornado “alleys” during his graduate studies at the University of Akron. As shown in Figure 2, these include the traditional Tornado Alley as well as Hoosier Alley (centered on Indiana), Carolina Alley (spanning parts of the North Carolina Piedmont and Coastal Plain), and Dixie Alley (extending from far east Texas to north Georgia).
 

Figure 2. The four “alleys” of peak U.S. tornado activity, as analyzed by geographer Michael Frates. Colored boxes denote the relative frequency of long-track F3, F4, and F5 tornadoes between 1950 and 2006. Image credit: Michael Frates, University of Akron.
 
 
It’s easy to quibble over exactly what constitutes a tornadic alley, or where its boundaries should be drawn, but it’s also clear that the southeast U.S. is especially tornado-vulnerable. That point was hammered home by the 2011 Super Outbreak. Concentrating its fury in Mississippi, Alabama, Georgia, and southern Tennessee, the outbreak took more than 300 lives on April 27. It was the nation’s largest single-day tornado toll since the Super Outbreak of April 3, 1974, which also hit the same area hard (as well as points further north).
 
With their constituents suffering, regional lawmakers decided to work toward bringing tornado research from the Plains into the hard-hit Southeast. Congress provided guidance in 2014 to NOAA and NSF to collaborate in organizing and conducting a VORTEX-SE research study, and more than $5 million was allocated by Congress in fiscal year 2016. VORTEX-SE organizers have put in place a planning process for a succession of research projects that, if funding support continues, are designed to lead to improvements in tornado forecasts and responses in the Southeast.
 
A grab bag of threats
Tornadoes obey the same laws of physics no matter where they develop, but some types of tornadoes are especially problematic in the Southeast. Violent “wedge” tornadoes can be more difficult to see than on the Plains because of lower cloud bases produced by richer low-level moisture and because of the widespread hills and trees. The region’s high frequency of severe weather year-round leads to a perennial threat from weaker, short-lived (but still dangerous) tornadoes produced by quasi-linear convective systems (QLCSs), or what are traditionally known as squall lines. Thunderstorms are often moving quickly, sometimes at more than 50 mph. Nighttime tornadoes are also more common here than in many areas, which adds to public safety concerns.
 
Rebecca Morss (National Center for Atmospheric Research) is shepherding the VORTEX-SE social science component as a member of the project’s scientific steering committee. “The Southeast has unique issues related to tornadoes--meteorologically, operationally, and societally,” Morss told me in an interview. One key example: about half of the nation’s mobile/manufactured homes are located across the Southeast, where they constitute more than 20% of housing units in many counties. Thousands of manufactured homes are located on small acreages, which complicates the task of getting to shelter.
 
Along with challenges unique to the Southeast, Morss and colleagues are teaming up with NWS forecasters to advance a longer-term, national-scale effort to improve forecast and warning communication. Those warnings aren’t received in a vacuum, she stressed. “What do people do when they get a warning? Do they look at social media?  Do they look outside? We often think of individual decision making, but it’s really a social process. People are usually making decisions about how to act in conjunction with other family members and what friends are doing.”
 

Figure 3. A soda machine is seen in debris in the Holt neighbourhood of Tuscaloosa, Alabama, on May 1, 2011, following the devastating tornado of April 27. Many trailer homes in the area were destroyed by the tornado. Image credit: Mandel Ngan/AFP/Getty Images.
 
 
Spinning up an experiment at tornadic speed (or close to it)
Most major atmospheric research campaigns--including the first two VORTEX projects--emerge after several years of proposals (typically to NSF and/or NOAA), which means the scientific goals tend to be fully developed by the time the campaign gets under way. In the case of VORTEX-SE, researchers have funding in hand while they continue to work out the priorities and strategies that are most relevant to the study area. A workshop held in Huntsville last November drew more than 100 on-site participants, with virtual collaborations boosting the total number of researchers involved to around 150.

“It’s turning into a really good science program,” said coordinator Erik Rasmussen. A veteran tornado researcher involved with the two prior VORTEX projects, Rasmussen is steering VORTEX-SE from NOAA’s National Severe Storms Laboratory, the official organizing agency.
 
Much of the funding thus far has gone into an initial set of NOAA-allocated grants to scientists scattered across the Southeast and beyond. Some of these research threads will extend beyond the spring, such as one aimed at improving prediction of tornadoes in landfalling hurricanes and tropical storms. Others are being woven into a set of intensive observing periods this March and April. These IOPs will be conducted from an operations center at the University of Alabama in Huntsville’s new SWIRLL facility (Severe Weather Institute & Radar Lightning Laboratory). Local researchers will figure heavily into VORTEX-SE. Along with a number of scientists and facilities from UAH’s Atmospheric Science Department, the project will draw on the capabilities of the Huntsville-based NASA Marshall Space Flight Center and its expertise in lightning and storm electricity.
 
This year’s field campaign will focus on the boundary layer, the lowest mile or so of the atmosphere. Many of the Southeast’s severe weather episodes are intense but localized, with high wind shear and relatively low instability (or CAPE). “Some people have hypothesized there are little pockets of CAPE in these situations,” says Rasmussen. “Are models keeping up with such developments? I think that’ll end up being the main focus this year.”
 

Figure 4. A StickNet unit is deployed in far western Nebraska ahead of a tornado-producing thunderstorm on June 5, 2009, during the VORTEX2 experiment. Image credit: Bob Henson.
 
 
Out in the field, there’ll be radiosonde-launching mobile units from the University of Louisiana at Monroe as well as Mississippi State, North Carolina State, Purdue, and Texas Tech. Fixed-site launches will be conducted by UAH and NOAA’s Air Resources Laboratory. A dozen compact StickNet instrument packages from Texas Tech will also be deployed. To see how much the StickNet data improves model performance, NOAA’s Earth System Research Laboratory will carry out post-storm runs using the high-resolution HRRR and RAP models. The extra data may help better characterize pools of cool surface air left behind by thunderstorms. This, in turn, could improve short-term forecasts of storm rotation and longevity.
 
Rather than moving along with major supercells for dozens or even hundreds of miles, as was the case during prior VORTEX campaigns, the observing platforms this spring will be concentrated in northern Alabama and southern Tennessee, largely in the warning area served by the National Weather Service office in Huntsville.
 
“We have greatly limited mobility, and to complicate that, we have fast-moving storms,” said Rasmussen. “We’re going to throw a network up in a good dual-Doppler coverage area and take most of the obervations in that network.”
 
Another VORTEX veteran, Yvette Richardson (Pennsylvania State University), is heading up the physical science wing of the VORTEX-SE steering committee. “We’re putting a great deal of thought into which problems can be addressed in the Southeast, given the topography and tree cover. It's a challenging part of the country to do an observing campaign.” Rounding out the steering committee is Kevin Laws, science and operations officer at the NWS/Birmingham office, who will shepherd the operational science elements.
 


Tornadoes and terrain
The role of landscape will get increasing emphasis in 2017 and beyond. One of the current grant-funded projects, led by NOAA/ARL, will use high-resolution, 3-D observations to assess the variations in the low-level atmosphere as well as the roughness of the land surface. “This knowledge will lead to a better understanding of how local conditions can lead to more favorable environments for tornadoes when conventional understanding would indicate tornadoes are unlikely,” states the grant abstract.



Figure 5. Rotational tracks corresponding to tornadoes during the Super Outbreak of April 27, 2011. This map was produced by the On-Demand system of NOAA’s National Severe Storms Laboratory. Image credit: NOAA/NSSL.
 


The extent to which tornadic storms can be shaped by landscape and topography has long been controversial and difficult to assess. Generations of Tornado Alley dwellers grew up hearing about towns that were “protected” from tornadoes by hills or ridges. (Some residents of Topeka, KS, thought that a local feature called Burnett’s Mound would steer tornadoes away, until a devastating twister plowed through town on June 8, 1966, killing 17 people.) It’s now clear that tornadoes can maintain their strength while climbing and descending hills, a message forecasters have been stressing for years. Yet this doesn’t rule out the possibility that some tornadic storms get a boost from landscape features that help to channel low-level winds.
 
At Penn State, graduate student Branden Katona is looking into such possibilities. He’s built a climatology of where environmental characteristics that could influence storm rotation are maximized, based on three years of HRRR forecasts across the Southeast. Katona focused on two variables: significant tornado parameter (STP, which incorporates both instability and wind shear) and storm-relative helicity (SRH, a measure of potential storm rotation). “Quite a few local maxima in both SRH and STP follow terrain contours,” Katona pointed out in an email. “In particular, the SRH maxima are aligned with local ridge axes in both northeastern Alabama and in the Great Smoky Mountains in southeastern Tennessee. Additionally, a local STP maximum stretching from northeast Mississippi down into western Alabama is aligned with a local valley axis.” Katona will soon be comparing the HRRR data to actual tornado paths: “I expect at least some of the model perturbations to coincide with clusters of tornadoes.”

Bob Henson
 
PS from Dr. Jeff Masters and Bob Henson: Help us re-name this blog!
As regular readers know, we have been co-authoring this blog since early 2015. It’s time for a name change from “Dr. Jeff Masters’ WunderBlog” to a new name that reflects our dual authorship. We have some ideas in mind, but we’re hoping that you, our readers, can help us expand our pool of nominees. We’re looking for a cool, pithy name--ideally just two or three words--that reflects the spirit of this blog in covering both weather and climate, with particular emphases on tropical meteorology, severe weather, and climate change. Please feel free to chime in with your suggestions in the comments section of this post. If you’re a WU member, you can drop us a line via WU Mail if you prefer. All suggestions made by March 10 will be considered. Thanks in advance for your creativity!


Figure 6. Climatological locations of storm-relative helicity (STH) in the lowest kilometer of the atmosphere (left) and elevation (right), generated by the high-resolution HRRR model and averaged across 358 days with thunderstorms during the period Feb. 1 through Sept. 30, 2013-2015. All STH calculations are at 2100 UTC (4 PM or 5 PM local time, around peak solar heating, when most surface-based thunderstorms would be developing or ongoing). Storm-relative helicity indicates the likelihood that updrafts in a right-moving supercell storm will rotate. Image credit: Branden Katona, Penn State University.


Tornado

At Least 5 Killed as Tornadoes, Howling Thunderstorm Winds Rake Eastern US

By: Bob Henson and Jeff Masters , 5:58 PM GMT on February 25, 2016

Whipping northward at interstate speeds, multiple rounds of severe thunderstorms raced from the Carolinas to New England on Wednesday and early Thursday. The springlike round of severe weather--which extended unusually far north for February--took one life in South Carolina and at least four in Virginia, making Wednesday the latter state’s deadliest tornado day since the notorious Super Outbreak of April 27, 2011. Three people, including a two-year-old boy, were killed in hard-hit Waverly, VA, and another man died in Appomattox County (see photo of the Appomattox tornado at bottom).


Figure 1. Lightning lights up the night sky behind a home in Waverly, Va, that was hit by a tornado earlier in the day, Wednesday, Feb. 24, 2016. Fast-moving storms swept into Virginia on Wednesday, leaving at least three dead in the tiny farming town of Waverly and injuring several others across the state, authorities said. Image credit: Todd Spencer/ The Virginian-Pilot via AP.

Fierce winds at the surface and aloft
Wednesday’s storms lived up to the soberly worded outlooks issued by NOAA’s Storm Prediction Center (SPC) earlier in the day. Local NWS offices across the region had their hands full keeping up with dozens of tornadic supercells and line segments with embedded rotation. Many locations were under tornado warnings at least twice throughout the day. Winds at all levels were howling from the south, which allowed individual storm cells to scream north while lines of storms translated slowly eastward. At least one warning cited a cell motion of 100 mph, which is extremely unusual in an NWS warning. These “training” echoes led to many 2” - 3” rain totals from the Washington, D.C., area north across much of New England. Capital Weather Gang’s Jason Samenow dubbed the storm in D.C. “arguably one of the fiercest since the June 2012 derecho.”

Even apart from thunderstorms, the southerly winds produced widespread gusts above 40 mph. By 7 am EST Thursday morning, NOAA/SPC had racked up at least 17 tornado reports and more than 300 reports of high wind, extending from Florida to Maine. Hail up to baseball size was reported near Tungsten, NC, and Castle Heights, VA.

The surprise element Wednesday night was how far north the action extended. A wedge of cold air eroded more quickly than expected, allowing warm, moist air to surge north ahead of a slow-moving cold front. This warm front set the stage for late-night thunderstorms that would be impressive for the region in May, much less February. By late Wednesday night, severe thunderstorm watches had been placed as far poleward as southern Vermont and eastern Massachusetts “If not unprecedented, I'd characterize yesterday as ‘highly unusual’,” said Greg Carbin, warning and coordination meteorologist for NOAA/SPC.

At 9 PM EST Tuesday, Boston’s Logan Airport was fogged in, with nearly calm winds and the temperature a clammy 42°F. By 3 AM Wednesday, the temperature had jumped to 61°F, with south winds gusting to 46 mph. Meteorologist Jacob Wycoff noted that the last time western Massachusetts experienced a severe thunderstorm warning in February was nearly 20 years ago--on Feb. 22, 1997. Winds at the iconic Blue Hill Observatory, the nation’s oldest continuous weather station, gusted to 74 mph just before the storms moved in around 3 AM.


Figure 2. Model depictions of winds at 250 mb, or about 34,000 feet (left) and 850 mb, or about 5,000 feet (right), produced at 7:00 pm EST Wednesday, Feb. 24, 2016, and valid at 1:00 am Thursday. The strong upper-level jet at left was projected to head toward New England with 250-mb winds topping 140 knots (160 mph). Strong diffluence--evident in the wind contours parting as they approach New England--supported vigorous thunderstorm growth. At right, a large area of 850-mb winds was projected to exceed 64 knots (74 mph). Image credit: Levi Cowan, tropicaltidbits.com.


Figure 3. WunderMap radar depiction at 2:15 am EST Thursday showed a robust line of thunderstorms--several of them severe--moving across central New England, with weaker secondary storms over central New York. A shield of snow extended from Quebec into the central U.S.

Winter weather pummels Midwest
While the Eastern Seaboard grappled with springlike storms, areas from Missouri to Michigan were plastered by a more seasonable round of heavy snow. Power was knocked out to thousands, and dozens of vehicles were stuck overnight in Chicago’s Grant Park, according to weather.com. Accumulations of up to 11" hit the northern suburbs of Detroit, and the exceptionally wet, heavy nature of the snow led to warnings that heart attacks were likely for those with heart conditions who attempted to shovel the cement-like stuff.


Figure 4. My Davis Weather Station needed a solar panel brush-off after 11" of wet, heavy snow caked it overnight. The northern suburbs of Detroit where I live got the highest accumulations of anywhere in Michigan from the storm. - Jeff Masters

Next week: rinse and repeat?
After a more tranquil weekend and an uneventful start to next week, the eastern U.S. could see another powerhouse storm system. Long-range models are suggesting the potential for an inland nor’easter not unlike the one just departing, with severe weather again possible from the South to the mid-Atlantic and perhaps northward from there. El NIño commonly intensifies severe weather across the Gulf states during winter, but multiple rounds of severe storms north of the Carolinas would be a more unorthodox happening.

Portlight disaster relief charity responds to this week's tornadoes
The Portlight.org disaster relief charity, founded and staffed by members of the wunderground community, is responding to this week's devastating tornadoes. Since a large area was affected, Portlight is focusing on identifying those who lost their mobility thru loss of walkers, wheel and powerchairs, and where home ramps will need to be rebuilt or replaced. You can check out their progress on the Portlight Blog or donate to Portlight's disaster relief fund at the portlight.org website.

We’ll be back on Friday with our next post.

Bob Henson and Jeff Masters



Extreme Weather Severe Weather Winter Weather

Tornadoes Kill Three in Southern U.S.; Significant Tornado Outbreak Today in VA, NC

By: Jeff Masters , 4:25 PM GMT on February 24, 2016

The deadliest severe weather outbreak thus far in 2016 hit the Deep South on Tuesday, when at least eighteen tornadoes tore across portions of Louisiana, Mississippi, Alabama, Florida, and Georgia. Hardest hit was Louisiana, where the town of Convent saw a tornado rip through an RV park, killing two and injuring 31, with seven of those people in critical condition. An additional fatality was reported in a mobile home near Purvis, Mississippi. Major damage occurred late Tuesday morning in Prairieville, southeast of Baton Rouge, where a Gold's Gym and several other buildings nearby were heavily damaged around the time a tornado was reported in the area. Just 18 miles northeast, in Livingston, several homes had their roofs completely torn off. For the second time this month, a tornado caused major damage in Escambia County, located in the far western portion of the Florida Panhandle near Pensacola. A rotating supercell thunderstorm that formed over the Gulf of Mexico moved ashore and spawned a tornado that crossed Interstate 10, flipping several cars and a tractor trailer on the Escambia Bay Bridge, leaving the highway closed from mile marker 17 to mile marker 43. Twenty-four units of The Moorings apartment complex in Pensacola were completely destroyed, and an additional six suffered minor damage, according to Be Ready Escambia, the official disaster readiness website of the county's emergency management agency.


Figure 1. Destroyed trailers and vehicles are all that remain of the Sugar Hill RV Park after a tornado hit Convent, Louisiana on Tuesday, Feb. 23, 2016. The tornado killed two people in the trailer park. In total, 31 people were hospitalized from the trailer park, and seven were in critical condition, officials told the AP. (AP Photo/Max Becherer)


Figure 2. A large waterspout with two smaller satellite waterspouts moved across Louisiana's Lake Ponchartrain on Tuesday afternoon, February 23, 2016. Image credit: Casey Rogers/Facebook. This impressive WWLTV.com video shows the waterspouts in more detail. Thanks go to wunderground member Patrap for posting this link in the blog comments.


Figure 3. Severe weather reports for Tuesday, February 23, 2016, from NOAA’s Storm Prediction Center.

Another dangerous severe weather day on Wednesday
The storm system responsible for Tuesday’s severe weather is moving northeast, and severe thunderstorms began firing up on Wednesday morning ahead of the cold front that was sweeping through Florida, South Carolina, North Carolina. Tornado warnings were issued late Wednesday morning in Tampa, Florida, and in southern North Carolina, but the main severe threat will occur late Wednesday afternoon in eastern North Carolina and southeastern Virginia, where a strong mid-level jet stream with winds in excess of 125 mph and plenty of wind shear will provide spinning motion to afternoon thunderstorms that will fire up in the unstable air ahead of the approaching cold front. NOAA’s Storm Prediction Center is warning of the possibility of strong EF2 and EF3 tornadoes in this area, along with severe thunderstorms likely to cause straight-line wind damage.


Figure 4. The severe weather outlook for Wednesday, February 24, 2016 from NOAA's Storm Prediction Center calls for another major day of severe weather, with portions of eastern North Carolina and eastern Virginia under a "Moderate Risk" of severe weather.

You can follow today's outbreak on our special Live Blog.

Jeff Masters

Tornado

Late-Winter Severe Weather on Tap Across Southeast; Strong Tornadoes Possible

By: Bob Henson , 7:45 PM GMT on February 23, 2016

A compact, potent streak of upper-level energy diving into the Southeast on Tuesday is expected to trigger widespread severe weather from Tuesday afternoon into Wednesday, with the potential for a regional tornado outbreak across the Deep South late Tuesday. The set-up has some of the earmarks of earlier outbreaks this winter that have brought intense storms to the central Gulf Coast and Florida, but in this case the dynamics in play are especially strong. At midday Tuesday, NOAA’s Storm Prediction Center (SPC) was calling for a moderate risk of severe weather from far eastern Louisiana across southern Mississippi and Alabama into far southwest Georgia and the western Florida Panhandle. Strong tornadoes are possible across the moderate-risk area. A larger slight-risk area surrounds the moderate risk (see Figure 1).

Severe weather had already kicked off just after noon CST Tuesday in southeast Louisiana, as an apparent tornadic waterspout formed over Lake Ponchartrain. Waterspouts often develop from relatively modest lines of cumulus clouds, typically moving quite slowly, but they can also emerge from severe thunderstorms in much the same way as land-based tornadoes do. These tornadic waterspouts can move quickly onshore and pose a much greater threat to coastal communities. A tornado watch was issued late Tuesday morning across most of southern Louisiana, with more watches sure to follow further east.



Figure 1. Areas of severe weather anticipated by NOAA’s Storm Prediction Center for Tues., Feb. 23 (left, extending through 7:00 am EST Wednesday) and Wed., Feb. 24 (right, extending through 7:00 am EST Thursday). The strongest activity is expected late Tuesday near the upper Gulf Coast and on Wednesday afternoon over eastern North Carolina. These outlooks were issued at 11:30 am EST (left) and 12:30 pm EST (right) on Tues., Feb. 23. Image credit: NOAA/SPC.


Today’s watchword: dynamics
The upper-level feature heading toward the Gulf Coast is a small but very energetic lobe at the base of a larger upper trough moving across the central states into the Midwest. A ribbon of jet-stream-level winds exceeding 120 mph, over the central Rockies early Tuesday, will be diving into the southeast US by late Tuesday. The lobe will spin up a powerful surface low expected to track from Louisiana on Tuesday afternoon to western Ohio by Wednesday, pushing a cold front across the Southeast. Warm, unstable air from the Gulf of Mexico will struggle to make it very far northward before the front arrives, but moderately unstable air with dew points above 60°F should envelop most of Mississippi and Alabama by Tuesday night. A narrow wedge of instability will shoot up the East Coast on Wednesday, perhaps making it north of the Washington, D.C., area by evening.


Figure 2. Jet-stream winds at the 250-mb level (about 34,000 feet) predicted by the GFS model in its 24-hour forecast valid at 7:00 am EST Wednesday, Feb. 24, 2016. Very strong winds will be in place across the severe weather risk area late Tuesday night. Upward motion favoring supercells will be maximized near the upper-level jet streak, or across southern Mississippi and Alabama and the western Florida Panhandle late Tuesday night. Image credit: Levi Cowan, tropicaltidbits.com.


In some cases, the modest amounts of instability on Tuesday and Wednesday might produce only garden-variety thunderstorms. However, in this case the relatively low instability will be more than compensated for by extremely strong dynamics. It is rare for an upper-level feature this strong to travel so far south across the upper Gulf Coast. As the surface low organizes well to the northwest, vertical wind shear will dramatically increase across the moderate risk area, as winds strengthen at all levels and veer from southeasterly near the surface to southwesterly just aloft. The wind shear will be approaching levels observed in some of the stronger Gulf Coast severe weather outbreaks on record. WU contributor Lee Grenci has a new post explaining why the low-level jet stream is especially important on a day like today in generating storm rotation.

At midday Tuesday, Weather Channel’s Dr. Greg Forbes raised the TOR:CON level to 8 across the SPC’s moderate-risk area. This means there is a 80 percent chance of a tornado within 50 miles of any location in the specified areas.

Residents of the upper Gulf Coast within the moderate risk area who lack adequate shelter at home would be well advised wherever possible to identify potential safe-shelter areas before nightfall. Storms will be moving and evolving at an increasingly faster pace as this evening unfolds. The most dangerous tornadoes are most likely to occur in any isolated supercell thunderstorms that develop ahead of the main front. However, strong winds and brief tornadoes are also possible with a squall line or line segments that should develop near the front later tonight.


Figure 3. Simulated radar reflectivity from the 14Z Tuesday run of the HRRR model, valid at midnight EST Tuesday night, Feb. 23, 2016. Even at this late hour, powerful thunderstorms should be rumbling across parts of Alabama, western Georgia, and the Florida Panhandle. Image credit: NOAA/ESRL.

Eastern NC at risk of strong tornadoes on Wednesday
Wednesday’s severe potential will depend on part on how extensive and long-lived Tuesday night’s storms end up becoming. However, there is some confidence that eastern North Carolina will be under the gun, given the timing of the system (it will be approaching eastern NC by mid/late afternoon, when surface temperatures and instability would normally be peaking). In its Day 2 convective outlook for Wednesday updated at 1:30 pm EST Tuesday, SPC introduced a risk area of significant tornadoes over eastern NC.

Follow the severe weather on our live blog
We’ve launched a WU live blog to provide frequent updates on the severe weather this afternoon and evening into Wednesday. You can get to the live blog from this link and from the “Tornado Risk” box on the right hand-side of the WU home page.

Bob Henson

Severe Weather

Incredible Destruction and at Least 21 Deaths in Fiji From Tropical Cyclone Winston

By: Bob Henson and Jeff Masters , 5:32 PM GMT on February 22, 2016

At least 21 deaths had been reported by late Monday Fiji time as the island nation slogged through the daunting early stages of recovery from ferocious Cyclone Winston, the strongest tropical cyclone on record in the Southern Hemisphere. Officials expect the death toll to rise when they're finally able to reach outlying islands that were hit hardest by the powerful storm, said the BBC, and it would not be surprising if Winston ends up being the deadliest and costliest natural disaster in Fiji's history. Fiji's deadliest tropical cyclone in recorded history was Category 3 Cyclone Eric of 1985, which made a direct hit on the capital of Suva, killing 25.

Since satellite records began in 1970 (with high-quality satellite images only available since 1990), just eleven Cat 5s (including Winston) have been observed anywhere in the South Pacific east of Australia. Winston is the strongest of these, according to records from the Joint Typhoon Warning Center. As Winston passed over Fiji’s Koro Island on Saturday, its winds were estimated by satellite at 180 mph (note: Winston was originally assessed to have 185 mph peak winds, but these were reduced to 180 mph in post-analysis.) This puts Winston in fifth place for Earth's strongest landfalling tropical cyclone on record. The only stronger storms were 2013's catastrophic Super Typhoon Haiyan (190 mph winds in Samar, Philippines), 2016's Super Typhoon Meranti (190 mph winds on Itbayat Island in the Philippines), 1959’s Typhoon Joan (185 mph winds in Taiwan) and the 1935 Labor Day Hurricane in the Florida Keys (185 mph winds). Wind speeds of 180 mph are characteristic of an EF4 tornado, and damage photos from the New Zealand Air Force showed many areas of incredible damage characteristic of at least EF3 tornado speeds (136 - 165 mph) on Koro Island (Figure 1.)


Figure 1. Wind damage in the village of Vatulele, on the northeast tip of Koro Island, Fiji. Tropical Cyclone Winston was at peak strength with 185-mph winds (Category 5 strength) when the eye passed directly over this village on February 20, 2016. Without knowing the quality of the construction, a good guess is that damage in this photo is from EF3 tornado wind speeds (136 - 165 mph), implying that this portion of Koro did not receive the full force of Winston's winds. This may be because high terrain behind this village blocked the full force of the wind--similar to what happened in Tacloban, Philippines, during the landfall of Super Typhoon Haiyan when it was at Category 5 strength. Image credit: Fijian government Facebook page.


Figure 2. Infrared imagery of Hurricane Winston as it bore down on the northeast coast of Fiji’s largest and most populous island, Viti Levu, on February 20, 2016. Koro Island (not shown) is located beneath the eastern eyewall of Winston, with the eye of Winston having passed directly over the island. Image credit: NOAA Weather Prediction Center.

A terrible track
Despite its relatively small size, Winston successfully took aim at Fiji along an unusual and especially destructive track. The cyclone had arced well south and east of Fiji last week before doing a 180-degree reversal in track and heading westward toward Fiji, strengthening from Category 2 to Category 5 en route. The storm’s powerful eyewall passed directly over several smaller islands and ground across the northern coast of Viti Levu, Fiji’s largest and most populous island. Photos taken from aboard New Zealand Air Force planes on Sunday, Feb. 21, 2016, and posted by the Fiji government on Facebook revealed the extent of the devastation from Winston on the island of Koro (see Figure 1) as well as Lau and Taveuni. The more highly touristed areas of Fiji, largely on Viti Levu, experienced relatively little damage, and no tourist casualties have been recorded, according to a Guardian report. On the west side of Viti Levu, Nadi International Airport resumed limited operations on Sunday, which will greatly facilitate relief efforts at the more remote islands. Most of the damage from WInston was due to the storm's extreme winds, though storm surge expert Hal Needham documented evidence of a storm surge of up to ten feet (3 meters) in a Monday blog post.


Figure 3. Cyclone Winston has carried out a large counterclockwise loop since its designation as a tropical cyclone on Feb. 10, 2016 (beginning of track at upper left). This tweet from Dan Lindsey includes a 12-day loop of Winston imagery from Japan’s Himiwari-8 satellite.

Patricia and Winston: strongest cyclones in Northern and Southern Hemisphere records
Remarkably, both the Northern and Southern Hemisphere have experienced their strongest cyclones in decades of record-keeping in the space of the last five months. NOAA recently announced the result of its post-storm analysis of Hurricane Patricia from October 2015, which spun up phenomenal sustained winds of 215 mph--the strongest ever measured by instruments via Hurricane Hunter aircraft--as the storm was approaching the Pacific coast of Mexico. Like Winston, Patricia was a relatively small storm, so its central pressure was not as low as its fierce winds might imply.

Since early 2015, we have had four Category 5 landfalls: Tropical Cyclone Pam (Vanuatu), Super Typhoon Maysak (Micronesia), Super Typhoon Noul (Philippines), and Cyclone Winston (Fiji). (Patricia was a strong Category 4 at landfall.) Although several of these tropical cyclones left major devastation in island nations that have relatively modest resources, we can take some comfort in the fact that none produced the kind of tragic death toll that occurred when Haiyan came ashore in the central Philippines. Haiyan was a large and fearsomely strong typhoon to begin with, and its destructive power was greatly exacerbated by its track into a large city on a shallow coastline prone to storm surge. The same could have easily occurred with several recent Cat 4s/5s: for example, only a slight eastward jog could have sent Patricia into Manzanillo Bay and the city of Manzanillo, Mexico. The very rapid strengthening of both Patricia and Winston--well beyond official forecasts in both cases--is a sobering reminder of the potential of real catastrophe in many areas, including the United States.


Figure 4. The most intense world tropical cyclones at landfall, using the advisories taken from the National Hurricane Center in the Atlantic and Eastern Pacific, and the Joint Typhoon Warning Center (JTWC) for the rest of the world's oceans. Both agencies use 1-minute averaging times for their advisories, as opposed to the 10-minute averaging time used to report wind speeds by most international weather agencies and at most international airports. Note that Super Typhoon Haiyan was originally assessed to have 195 mph winds at landfall by JTWC, but these were reduced to 190 mph after a post-season reanalysis. Also, Hurricane Camille's winds at landfall have also been reduced in a recent reanalysis, from 190 mph to 175 mph.

Climate change and Category 5s
In 2015, Earth saw a total of nine Category 5 storms, the second-highest total on record. This explosion of cyclonic fury was fed by ocean temperatures that were at record-warm levels globally, with especially warm readings across tropical and subtropical areas. El Niño has played a large role over the last few months by spreading warm surface water across vast swaths of the Pacific. However, Earth has also experienced a decade of intensified oceanic heat storage (which largely explains the temporary slowdown in the rate of atmospheric warming from about 2000 to 2012).

Tropical cyclones are heat engines at heart: they transfer energy from low-latitude oceans to the higher-latitude atmosphere. As human-produced greenhouse gases continue to pump energy into Earth’s oceans (where more than 90% of the excess heat from those greenhouse gases is stored), it is no surprise that some of that heat is being expressed in the form of record-setting typhoons, hurricanes, and cyclones. Now that ocean temperatures are considerably warmer than they were a few decades ago, the maximum potential intensity a hurricane can reach is higher. Climate models generally agree that we can expect a greater proportion of Earth’s tropical cyclones to attain Category 5 strength over the coming decades.

At Discover's ImaGeo blog, Tom Yulsman has an excellent distillation of Winston's connections to climate change as well as El Niño and the Madden-Julian Oscillation.

UNICEF and Save the Children are asking for donations to assist in Fiji relief efforts.

Dangerous weather brewing for Tuesday along Gulf Coast
We're keeping our eye on an expected outbreak of severe weather on Tuesday that could bring several strong tornadoes along the central Gulf Coast. Watch for more details here on Tuesday.

Bob Henson and Jeff Masters


Figure 5. Expected change in Atlantic Category 4 and 5 hurricanes per decade expected by the year 2100, according to Knutson et al. (2013), "Dynamical Downscaling Projections of 21st Century Atlantic Hurricane Activity: CMIP3 and CMIP5 Model-based Scenarios." This research used the latest generation of climate models from the 2013 IPCC report, and found "marginally significant" increases in Atlantic Category 4 and 5 hurricanes of 39% - 45% by 2100.


Hurricane

Winston's 180 mph Winds in Fiji: Southern Hemisphere's Strongest Storm on Record

By: Jeff Masters , 6:47 PM GMT on February 20, 2016

The strongest storm in recorded history for the Southern Hemisphere--mighty Category 5 Tropical Cyclone Winston--smashed through the islands of Fiji Friday night and Saturday morning with top sustained winds estimated at 180 mph (note: Winston's top winds were originally estimated at 185 mph, but these were reduced to 180 mph in post-analysis.) These winds vaulted Winston into a tie as the third strongest landfalling tropical cyclone in world recorded history (see Figure 3). Winston began its march at Category 5 strength through the Fiji Islands beginning at 18 UTC (1 pm EST) Friday. At that time, Winston had 165 mph winds as it moved westwards over the small Fiji island of Vanua Balavu (population 1,200). The island's airport was in the western eyewall of Winston, and at 18 UTC measured 10-minute average winds of 106 mph (roughly equivalent to 120 mph winds using the U.S. 1-minute averaging time.) Winston continued to intensify, then crashed ashore on the Fiji island of Koro (population 4,500) at peak strength--sustained winds of 185 mph--near 02 UTC Saturday (9 pm EST Friday.) This is the third strongest landfall by any tropical cyclone, globally, in recorded history. Only Super Typhoon Haiyan's 190 mph winds at landfall in 2013 in Samar, Philippines, and Super Typhoon Meranti's 190 mph winds at landfall in Itbayat Island, Philippines have been rated higher. After likely demolishing most of Koro with a long period of sustained winds of EF4 tornado strength, Winston's northern (weaker) eyewall brushed the south coast of Fiji's second largest island, Vanua Levu. The city of Nambouwalu on the south coast of Vanua Levu reported 10-minute sustained winds of 121 mph at 06 UTC Saturday (roughly equivalent to Category 4 winds of 135 mph using the U.S. 1-minute averaging time.) Winston then wobbled more to the west-southwest, possibly due to interaction with the high terrain of the two largest islands of Fiji. Maintaining winds of 180 mph, Winston slammed ashore along the northeast coast of Fiji's main island of Viti Levu in Rakiraki, a district of close to 30,000 people, near 07 UTC Saturday. The eye of Winston travelled westwards along the north coast of Viti Levu for two hours, pounding the entire north coast of the island with the strongest part of the storm, the southern eyewall. When Winston finally emerged from the island near 09 UTC Saturday, the storm was slightly weaker, but still had Category 5 winds of 160 mph. At that time, the edge of Winston's south eyewall moved over the second largest city in Fiji, Lautoka (population 80,000). The top sustained winds at the Lautoka tide station were 83 mph, gusting to 110 mph. These 10-minute average winds imply that at least Category 2 hurricane conditions (95 - 100 mph 1-minute averaged winds) were likely experienced there (thanks go to wunderground member Carnivorous for this link.) Damage to Fiji is going to be severe to catastrophic, but it will be several days before the true scope of the destruction is realized.


Figure 1. Radar image from the Fiji weather service showing Tropical Cyclone Winston at 07 UTC Saturday, February 20, 2016. At the time, Winston was making landfall on Fiji's main island of Viti Levu as a Category 5 storm with 180 mph winds and a 915 mb central pressure.


Figure 2. Visible MODIS image from NASA's Terra satellite of Tropical Cyclone Winston taken at 0300 UTC February 20 (10 pm EST February 19), 2016. At the time, WInston was a Category 5 storm with 185 mph winds, and its eye was over Koro Island on Fiji. Image credit: NASA.

Winston the strongest tropical cyclone on record in the Southern Hemisphere
Winston's 180 mph sustained winds at its peak intensity at 00 UTC February 20 are tied for the highest for any Southern Hemisphere tropical cyclone ever rated by the Joint Typhoon Warning Center (JTWC). The other 180 mph cyclones were Cyclone Zoe of 2002 and Cyclone Monica of 2006. Winston's lowest central pressure as estimated by the Fiji Meteorological Service was 915 mb at 06 UTC February 20. This ranks Winston as the 29th most intense tropical cyclone in the Southern Hemisphere by pressure. The record lowest pressure is 890 mb by Cyclone Zoe of 2002. Winston's top winds were higher than its central pressure might imply because it was a relatively small cyclone, so the wind-generating difference in pressure was packed into a small area. Winston joins a very select club of Category 5 storms ever recorded to churn the South Pacific waters east of Australia. Since satellite records began in 1970 (with high-quality satellite images only available since 1990), just eleven Cat 5s (including Winston) have been observed in the South Pacific east of Australia. Only two of the ten previous Cat 5s have made landfall as a Category 5. The most recent was last year's Cyclone Pam, which was at its peak strength, with 165-mph Category 5 winds, when it passed over several small Vanuatu Islands to the north of Efate Island, Vanuatu's most populous island. The other Category 5 landfall was by Cyclone Zoe of 2002, which made a direct hit as a Category 5 storm on several small islands in the Temotu Province of the Solomon Islands with a total population of 1700. There was one other close call, though: the eye of Category 5 Tropical Cyclone Olaf passed 15 miles east of Ta'u, American Samoa, on February 16, 2005, but caused minimal damage.


Figure 3. The most intense world tropical cyclones at landfall, using the advisories taken from the National Hurricane Center in the Atlantic and Eastern Pacific, and the Joint Typhoon Warning Center (JTWC) for the rest of the world's oceans. Both agencies use 1-minute averaging times for their advisories, as opposed to the 10-minute averaging time used to report wind speeds by most international weather agencies and at most international airports. Note that Super Typhoon Haiyan was originally assessed to have 195 mph winds at landfall by JTWC, but these were reduced to 190 mph after a post-season reanalysis. Also, Hurricane Camille's winds at landfall have also been reduced in a recent reanalysis, from 190 mph to 175 mph.


Figure 4. Track of all Category 5 storms in the South Pacific (east of 135°E) since satellite records began in 1970. The strongest tropical cyclones in the Joint Typhoon Warning Center’s records are Zoe (2002/2003) and Monica (2006), which topped out with 180 mph winds. Image credit: Michael Lowry, TWC.

Forecast for Winston
Winston has moved past Fiji, and is no longer a high wind threat to the islands. Some residual heavy rains will continue over the western portion of Viti Levu on Saturday, though. Winston will likely weaken to Category 4 strength and head southwards during the remainder of the weekend, with no other islands in its path, thankfully. The cyclone may restrengthen slightly on Monday before a more significant weakening takes hold.

Fiji's tropical cyclone history
Category 4 Tropical Cyclone Evan of December 17, 2012 walloped Fiji with sustained winds of 135 mph, as the storm's southern eyewall--the most intense part of the storm--brought hurricane conditions to a long stretch of the north and west coasts of Fiji's main island, Viti Levu. According to a database maintained by NOAA's Coastal Service Center, Evan was the strongest tropical cyclone on record to affect Fiji's main island, with records going back to 1941 (however, more accurate satellite records extend back to only about 1990.) Evan did $109 million in damage (2012 dollars) to Fiji, making it the second most destructive storm in their history. The most devastating cyclone to affect Fiji in recorded history was Category 2 Cyclone Kina of January 1993, which killed 23 people and did $100 million in damage (1993 dollars.) The only deadlier storm than Kina was Category 3 Cyclone Eric of 1985, which made a direct hit on the capital of Suva, killing 25.


Figure 5. Tracks of all Category 1 and stronger tropical cyclones to pass within 100 miles of Fiji's main island of Viti Levu since 1941. Evan of 2012 (Category 4 with 135 mph winds) was the strongest cyclone on record to affect Fiji, but Winston of 2016 was much stronger. Image credit: NOAA's Coastal Service Center.

Links
Radar images from the Fiji weather service
Long radar loops of Winston
Satellite imagery from NOAA/NESDIS.
Fiji weather observations from wunderground.
Long Himawari-8 satellite animation in MP4 or animated GIF format.
Fiji Met Service Facebook page.


Cyclone Winston: Incredible conditions in Savusavu, Fiji, February 20, 2016. (Thanks go to wunderground member barabmz for posting this video in the comments.)

Jeff Masters

Hurricane

Fiji Pounded by its First Category 5 Storm on Record: Tropical Cyclone Winston

By: Jeff Masters and Bob Henson , 10:22 PM GMT on February 19, 2016

Mighty Category 5 Tropical Cyclone Winston, upgraded to 165 mph winds at 1 pm EDT Friday by the Joint Typhoon Warning Center (JTWC), is now the strongest tropical cyclone and first Category 5 storm on record to hit the South Pacific island nation of Fiji. The eye of Winston passed over the small Fiji island of Vanua Balavu near 1 pm EST Friday, when the storm was at Category 5 strength. At that time, the island's airport was in the western eyewall of Winston, and measured 10-minute average winds of 106 mph (perhaps roughly equivalent to 120 mph winds using the U.S. 1-minute averaging time.) Winston's central pressure was estimated at 920 mb at 1 pm EST Friday by the Fiji Meteorological Service. Winston is tracking north of its previous forecast track, and is now expected to make landfall on Fiji's second largest island, Vanua Levu, near Nambouwalu at approximately 0600 UTC (1 am EST) Saturday, as a Category 5 storm with 185 mph winds, according to the Joint Typhoon Warning Center (JTWC). This would make Winston the strongest tropical cyclone ever recorded in the South Pacific waters east of Australia.


Figure 1. Radar image from the Fiji weather service showing Tropical Cyclone Winston bringing rain to Fiji at 2121 UTC Friday, February 19, 2016.

On Friday afternoon, Winston was in a nearly ideal environment for intensification, with wind shear a moderate 10 - 15 knots, excellent upper-level outflow channels to both the north and the south, and sea surface temperatures (SSTs) near 31°C (88°F). These SSTs are about 1.5°C (2.7°F) above average. Unusually warm waters extend to great depth, giving Winston a high Tropical Cyclone Heat Potential (TCHP) in excess of 75 kJ/cm^2, a value which is often associated with rapid intensification. Satellite imagery on Friday afternoon showed that Winston had a large area of heavy thunderstorms concentrated in a donut shape around a 18-mile diameter eye, with very few outer spiral bands. This structure may qualify Winston as an "annular" hurricane--a special subclass of hurricanes which are more resistant to weakening than regular hurricanes. With such an annular structure, and with SSTs that will warm even further as Winston moves closer to Fiji, the storm should be able to maintain its Category 5 intensity until landfall.


Figure 2. Visible image from the Himawari satellite of Tropical Cyclone Winston taken at 2100 UTC (4 pm EST) February 19, 2016. At the time, WInston was a Category 5 storm with 165 mph winds. Image credit: Japan Meteorological Agency.

Winston only the 11th Category 5 storm east of Australia since 1970
Winston joins a very select club of Category 5 storms ever recorded to churn the South Pacific waters east of Australia. Since satellite records began in 1970, just eleven Cat 5s (including Winston) have been observed in the South Pacific east of Australia. The strongest tropical cyclones in the Joint Typhoon Warning Center’s records are Zoe (2002/2003) and Monica (2006), which topped out with 180 mph winds (thanks go to Phil Klotzbach of CSU for this stat.) Only two of the ten previous Cat 5s have made landfall as a Category 5. The most recent was last year's Cyclone Pam, which was at its peak strength, with 165-mph Category 5 winds, when it passed over several small Vanuatu Islands to the north of Efate Island, Vanuatu's most populous island (population 66,000.) The other Category 5 landfall was by the strongest tropical cyclone on record in the basin, Cyclone Zoe of 2002. Zoe made a direct hit as a Category 5 storm on several small islands in the Temotu Province of the Solomon Islands with a total population of 1700. There was one other close call, though: the eye of Category 5 Tropical Cyclone Olaf passed 15 miles east of Ta'u, American Samoa, on February 16, 2005, but caused minimal damage.


Figure 3. Track of all Category 5 storms in the South Pacific (east of 135°E) since satellite records began in 1970. The strongest tropical cyclones in the Joint Typhoon Warning Center’s records are Zoe (2002/2003) and Monica (2006), which topped out with 180 mph. Image credit: Michael Lowry, TWC.

Fiji's tropical cyclone history
Category 4 Tropical Cyclone Evan of December 17, 2012 walloped Fiji with sustained winds of 135 mph, as the storm's southern eyewall--the most intense part of the storm--brought hurricane conditions to a long stretch of the north and west coasts of Fiji's main island, Viti Levu. According to a database maintained by NOAA's Coastal Service Center, Evan was the strongest tropical cyclone on record to affect Fiji's main island, with records going back to 1941 (however, accurate satellite records extend back to only about 1990.) Evan did $109 million in damage (2012 dollars) to Fiji, making it the second most destructive storm in their history. The most devastating cyclone to affect Fiji in recent decades was Category 2 Cyclone Kina of January 1993, which killed 23 people and did $100 million in damage (1993 dollars.) The only deadlier storm than Kina was Category 3 Cyclone Eric of 1985, which made a direct hit on the capital of Suva, killing 25.


Figure 4. Tracks of all Category 1 and stronger tropical cyclones to pass within 100 miles of Fiji's main island of Viti Levu since 1941. Evan of 2012 (Category 4 with 135 mph winds) was the strongest cyclone on record to affect Fiji, but Winston of 2016 is stronger. Image credit: NOAA's Coastal Service Center.

Climate change and Fiji
Storm surge from Winston is of particular concern for Fiji, where sea level rise and coastal erosion have already begun to displace people. The nation includes more than 300 islands; some are volcanic in origin, while many of the smaller islands are low-lying coral atolls especially vulnerable to sea level rise. The nation has already assisted one small village, Vunidogolo, in moving to a new location as part of its climate change adaptation program. More than 30 other Fijian villages have been identified as vulnerable.

Although it represents only a tiny share of the world’s fossil fuel emissions, Fiji is doing its part to reduce them. On February 12, Fiji became the first nation on Earth to ratify the global pact on reducing greenhouse emissions that was hammered out at the UN Conference of Parties meeting (COP15) last December in Paris. Fiji has pledged to boost the renewable share of its electricity generation from around 60% in 2013 to near 100% by 2030. Together with energy efficiency improvements, this will reduce Fiji’s carbon dioxide emissions from fossil fuels in 2030 by roughly 30% compared to a business-as-usual approach.


Figure 5. In February 2014, the village of Vunidogoloa on Vanua Levu became the first community in Fiji to relocate because of coastal erosion and flooding attributed in part to climate change. The village moved to higher ground two kilometers inland. Image credit: Nansen Initiative, courtesy UN Office for the Coordination of Humanitarian Affairs.

Links
Radar images from the Fiji weather service
Long radar loop of Winston
Satellite imagery from NOAA/NESDIS.
Fiji weather observations from wunderground.

We'll be back on Saturday with an update on Winston.

Jeff Masters and Bob Henson

Hurricane

Trouble in Paradise: Cat 4 Winston May be Fiji's Strongest Tropical Cyclone on Record

By: Jeff Masters and Bob Henson , 4:58 PM GMT on February 19, 2016

There's trouble in paradise. The strongest storm ever to threaten the South Pacific island of Fiji, Category 4 Tropical Cyclone Winston, is poised to make a direct hit on the island nation on Saturday. Winston's formidable winds of 145 mph are not expected to change much before then, and when the storm makes its expected landfall on Fiji's main island, Viti Levu, at approximately 1200 UTC (7 am EST) Saturday, the Joint Typhoon Warning Center (JTWC) expects that Winston will be Fiji's strongest tropical cyclone on record: a Category 4 storm with sustained winds of 145 - 150 mph. At 10 am EST Friday, winds at Vanua Balavu Island, which was in the western eyewall of Winston, were sustained at 46 mph, gusting to 103 mph. Winston's central pressure was estimated at 925 mb at 8:11 am EST Friday by the Fiji Meteorological Service.


Figure 1. Visible image from the VIIRS satellite of Tropical Cyclone Winston taken at 0115 UTC February 19, 2016. At the time, WInston was a Category 4 storm with 145 mph winds. Image credit: NASA.

On Friday morning, Winston was in a nearly ideal environment for intensification, with wind shear a low 5 - 10 knots, excellent upper-level outflow channels to both the north and the south, and sea surface temperatures (SSTs) near 30.5°C (87°F). These SSTs are about 1 - 1.5°C (1.8 - 2.7°F) above average. Unusually warm waters extend to great depth, giving Winston a high Tropical Cyclone Heat Potential (TCHP) in excess of 75 kJ/cm^2, a value which is often associated with rapid intensification. Satellite imagery on Friday morning showed that Winston had a large area of heavy thunderstorms concentrated in a donut shape around a 18-mile diameter eye, with very few outer spiral bands. This structure may qualify Winston as an "annular" hurricane--a special subclass of hurricanes which are more resistant to weakening than regular hurricanes. With such an annular structure, and with SSTs that will warm to 31°C (88°F) as Winston moves closer to Fiji, the storm should be able to maintain its Category 4 intensity until landfall.


Figure 2. Radar image from the Fiji weather service showing the outer spiral bands of Tropical Cyclone Winston bringing rain to Fiji at 1541 UTC Friday, February 19, 2016.

Fiji's tropical cyclone history
Category 4 Tropical Cyclone Evan of December 17, 2012 walloped Fiji with sustained winds of 135 mph, as the storm's southern eyewall--the most intense part of the storm--brought hurricane conditions to a long stretch of the north and west coasts of Fiji's main island, Viti Levu. According to a database maintained by NOAA's Coastal Service Center, Evan was the strongest tropical cyclone on record to affect Fiji's main island, with records going back to 1941 (however, accurate satellite records extend back to only about 1990.) Evan did $109 million in damage (2012 dollars) to Fiji, making it the second most destructive storm in their history. The most devastating cyclone to affect Fiji in recent decades was Category 2 Cyclone Kina of January 1993, which killed 23 people and did $100 million in damage (1993 dollars.) The only deadlier storm than Kina was Category 3 Cyclone Eric of 1985, which made a direct hit on the capital of Suva, killing 25.


Figure 3. Tracks of all Category 1 and stronger tropical cyclones to pass within 100 miles of Fiji's main island of Viti Levu since 1941. Evan of 2012 (Category 4 with 135 mph winds) was the strongest cyclone on record to affect Fiji, but Winston of 2016 is stronger. Image credit: NOAA's Coastal Service Center.


Figure 4. Radar image from the Fiji weather service showing the large eye of Tropical Cyclone Evan just north of Fiji at 2:50 pm local time (02:50 UTC) on Monday, December 17, 2012. At the time, the city of Nadi was in the southern eyewall of Evan, and recorded sustained winds of 52 mph, gusting to 104 mph. Sustained winds at Nadi increased to 69 mph three hours later.

Climate change and Fiji
Storm surge from Winston is of particular concern for Fiji, where sea level rise and coastal erosion have already begun to displace people. The nation includes more than 300 islands; some are volcanic in origin, while many of the smaller islands are low-lying coral atolls especially vulnerable to sea level rise. The nation has already assisted one small village, Vunidogolo, in moving to a new location as part of its climate change adaptation program. More than 30 other Fijian villages have been identified as vulnerable.

Although it represents only a tiny share of the world’s fossil fuel emissions, Fiji is doing its part to reduce them. On February 12, Fiji became the first nation on Earth to ratify the global pact on reducing greenhouse emissions that was hammered out at the UN Conference of Parties meeting (COP21) last December in Paris. Fiji has pledged to boost the renewable share of its electricity generation from around 60% in 2013 to near 100% by 2030. Together with energy efficiency improvements, this will reduce Fiji’s carbon dioxide emissions from fossil fuels in 2030 by roughly 30% compared to a business-as-usual approach.


Figure 5. In February 2014, the village of Vunidogoloa on Vanua Levu became the first community in Fiji to relocate because of coastal erosion and flooding attributed in part to climate change. The village moved to higher ground two kilometers inland. Image credit: Nansen Initiative, courtesy UN Office for the Coordination of Humanitarian Affairs.

Links
Radar images from the Fiji weather service
Himawari 8 satellite loops from NOAA/RAMMB (select Floater 1 Band 3, or American Samoa)
Satellite imagery from NOAA/NESDIS.
Fiji weather observations from wunderground.

We'll be back on Saturday with an update on Winston.

Jeff Masters and Bob Henson

Hurricane

Earth Rings in 2016 With its Warmest January on Record

By: Jeff Masters , 7:26 PM GMT on February 17, 2016

After recording its warmest year on record in 2015, Earth continued its record-warm streak into 2016, with January 2016 being the planet's warmest January since record keeping began in 1880, said NOAA's National Centers for Environmental Information (NCEI) on Wednesday. The month had the second warmest departure from average (+1.04°C) of any month since 1880, with only December 2015 being warmer. NASA also rated January 2016 as the warmest January on record, but said it edged out December 2015 for being the warmest month in the entire historical record--1.13°C above average. The four warmest months since 1880 (as measured by departure from average in the NASA database) were the past four months. Here are the top five warmest months in the historical record, according to NASA:

1) January 2016
2) December 2015
3) October 2015
4) November 2015
5) January 2007

January 2016 also marked the ninth consecutive month that the monthly temperature record was been broken and the fourteenth consecutive month (since December 2014) that the monthly global temperature ranked among the three warmest for its respective month in the NOAA database. Global ocean temperatures during January 2016 were the warmest on record, and global land temperatures were the second warmest on record. Global satellite-measured temperatures in January 2016 for the lowest 8 km of the atmosphere were the warmest in the 38-year record, according to the University of Alabama Huntsville (UAH). This is the fourth consecutive month the UAH database has registered a record monthly high.


Figure 1. Departure of temperature from average for January 2016, the warmest January for the globe since record keeping began in 1880. Record warmth was observed across a swath of northern Siberia where temperatures rose at least 5°C (9°F) above the 1981–2010 monthly average, as well as across parts of southeastern Asia, southwestern Asia and the Middle East, most of southern Africa, and areas of Central and South America. Record warmth was observed in all major ocean basins: various regions of the eastern and western Atlantic, particularly near coasts, part of the Barents Sea in the Arctic; the Southeast Indian Ocean to the south of Australia; most of the North Indian Ocean; parts of the eastern and central equatorial Pacific; and the western Mediterranean Sea. Image credit: National Centers for Environmental Information (NCEI).

Two billion-dollar weather disasters in January 2016
Two billion-dollar weather-related disasters hit the Earth during last month, according to the January 2016 Catastrophe Report from insurance broker Aon Benfield. Both were due to winter weather: Winter Storm Jonas in the Eastern U.S., and a remarkable cold wave in Eastern Asia. Both disasters cost at least $2 billion.


Disaster 1. A massive blizzard rocked the Mid-Atlantic and Northeast U.S. January 22 - 24, killing 58 and causing at least $2 billion in damage. The snowstorm was rated the 4th most severe to hit the area in the past 66 years, according to NOAA. In this image, we see residents being forced to walk in the streets of Washington, D.C. during the storm. Image credit: Joe Flood, NOAA.


Disaster 2. One of the most intense cold air outbreaks in decades brought record low temperatures and heavy snowfall throughout much of East Asia January 20 - 25, killing a combined 116 people in Taiwan, Thailand, China, Japan and South Korea. China reported more than $1.6 billion in damage from cold and snow, and Taiwan’s agricultural sector recorded its highest losses in 17 years. Total damage from the winter weather was estimated at $2 billion. In this image, we see row boats stuck in the ice of the frozen coastal waters of Jiaozhou Bay in Qingdao in eastern China's Shandong province on January 25, 2016. Image credit: STR/AFP/Getty Images.

Strong El Niño gradually weakening
January 2016 featured strong El Niño conditions in the equatorial Eastern Pacific, with sea surface temperatures (SSTs) ending up 2.5°C above average in the so-called Niño3.4 region (5°S - 5°N, 120°W - 170°W), where SSTs must be at least 0.5°C above average for five consecutive months (each month being a 3-month average) for an El Niño event to be declared. El Niño peaked in strength in late November 2015, when the weekly Niño3.4 temperature anomaly hit a record 3.1°C. The anomaly was still a hefty +2.5°C this week, and El Niño is not weakening as quickly as many forecasts have predicted. NOAA still expects a transition to neutral conditions during late Northern Hemisphere spring or early summer 2016, though, with a possible transition to La Niña conditions during the fall. Many of the El Niño computer models are predicting La  Niña conditions during the August-September-October peak of hurricane season, which could lead to an active Atlantic hurricane season (NOAA"s CFSv2 model is a noteworthy exception, with the latest ensemble average from Feb. 15 suggesting that weak El Niño conditions might hang on through at least autumn 2016.) Even though NOAA has not issued an official "La Nina Watch", the probability is trending towards one, said NOAA El Niño expert Michelle L'Heureux, in an interview with Reuters last week. El Niño model predictions are least likely to be accurate when issued during the period from February to May, though, which is called the "Predictability Barrier" for forecasting El Niño.

Arctic sea ice falls to lowest January extent on record
Arctic sea ice extent during January 2016 was the lowest in the 38-year satellite record, according to the National Snow and Ice Data Center (NSIDC). Air temperatures just above the surface, at the 925 mb level, were more than 6 degrees Celsius (13 degrees Fahrenheit) above average across most of the Arctic Ocean. These unusually high air temperatures were likely related to the behavior of the Arctic Oscillation (AO.) While the AO was in a positive phase for most of the autumn and early winter, it turned strongly negative beginning in January. By mid-January, the index reached nearly -5 sigma (five standard deviations) below average. The AO then shifted back to positive during the last week of January.

Notable global heat and cold marks set for January 2016
Hottest temperature in the Northern Hemisphere: 43.0°C (109.4°F) at Linguere , Senegal, January 13
Coldest temperature in the Northern Hemisphere: -55.3°C (-67.5°F) at Summit, Greenland, January 31
Hottest temperature in the Southern Hemisphere: 48.6°C (119.5°F) at Augrabies Falls, South Africa, January 5
Coldest temperature in the Southern Hemisphere: -46.3°C (-51.3°F) at Dome Fuji, Antarctica, January 28
(Courtesy of Maximiliano Herrera.)

Major weather stations that set (not tied) new all-time heat or cold records in January 2016
Sutherland (South Africa) max. 37.9°C, 4 January
Kimberley (South Africa) max. 43.3°C, 5 January
Prieska (South Africa) max. 44.7°C, 5 January
Fraserburg  (South Africa) max. 41.2°C, 5 January
De Aar  (South Africa) max. 42.8°C, 5 January
Upington (South Africa) max. 45.3°C, 5 January
Vanwyksvlei (South Africa) max. 43.9°C, 5 January
Queenstown (South Africa) max. 42.9°C, 5 January
Pofadder  (South Africa) max. 42.4°C, 5 January
Buffelsfontein (South Africa) max. 38.6°C, 5 January
Jamestown (South Africa) max. 38.7°C,  5 January
Cradock (South Africa) max. 43.8°C, 5 January
Van Zylsrus (South Africa) max. 45.4°C, 6 January
Kuruman (South Africa) max. 44.3°C, 6 January
Bloemhof (South Africa) max. 43.7°C, 6 January
Bloemfontein Airport (South Africa) max. 42.0°C, 6 January
Bloemfontein City (South Africa) max. 41.4°C,  6 January
Glen College (South Africa) max. 43.2°C, 6 January
Twee Riviere (South Africa) max. 45.4°C, 6 January
Welkom (South Africa) max. 41.4°C, 6 January
Ottosdal (South Africa) max. 42.4°C, 6 January
Estcourt (South Africa) max. 41.7°C, 6 January
Vryburg (South Africa) max. 43.7°C, 6 January
Ladysmith (South Africa) max. 43.0°C, 6 January
Taung (South Africa) max. 44.6°C, 6 January
Bethlehem (South Africa) max. 37.4°C, 6 January
Kroonstad  (South Africa) max. 41.0°C,  6 January
Bothaville  (South Africa) max. 41.8°C, 6 January
Royal National Park  (South Africa) max. 39.7°C, 6 January
Werda (Botswana) max. 43.3°C,  6 January
Tsabong (Botswana) max. 43.5°C,  6 January: New national record high for Botswana
Maun (Botswana) max. 43.8°C, 7 January: New national record high for Botswana
Gaborone (Botswana) max. 42.7°C, 7 January
Jwaneng (Botswana) max. 41.9°C, 7 January
Pretoria City  (South Africa) max. 42.7°C,   7 January
Pretoria Airport (South Africa) max. 38.7°C, 7 January
Johannesburg (South Africa) max. 38.9°C,  7 January
Johannesburg Aiport (South Africa) max. 35.9°C, 7 January
Frankfort (South Africa) max. 40.4°C,  7 January
Rustenburg (South Africa) max. 41.6°C, 7 January
Oudestad (South Africa) max. 42.5°C, 7 January
Ellisras (South Africa) max. 44.5°C,  7 January
Thabazimbi (South Africa) max. 44.7°C,  7 January
Warmbaths Towoomba (South Africa) max. 43.7°C,  7 January
Marico  (South Africa) max. 45.0°C, 7 January
Buffelspoort  (South Africa) max. 42.4°C, 7 January
Mara (South Africa) max. 42.4, 7 January
Bulawayo Airport (Zimbabwe) max. 39.3°C, 7 January
Gweru (Zimbabwe) max. 37.0°C, 7 January
Binga (Zimbabwe) max. 42.4°C, 8 January
Futuna Aiport (Wallis and Futuna, France) max. 35.8°C,  10 January: New territorial record high for Wallis and Futuna
Ambon (Indonesia) max. 36.0°C,  22 January
Xiamen (China) min. 0.1°C, 24 January
Fuzhou (China) min. -1.9°C, 24 January
Dachen Dao (China) min. -4.1°C, 24 January
Dongsha Dao (China) min. 12.6°C, 24 January
Tai Mo Shan (Hong Kong, China) min. -5.7°C,  24 January: New Territorial record low for Hong Kong
Su' ao (Taiwan) min. 5.0°C, 24 January
Xinwu  (Taiwan) min. 4.2°C, 24 January
Anbu (Taiwan) min. -3.7°C, 24 January
Zhuzihu (Taiwan) min. -1.5°C, 24 January
Kinmen (Taiwan) min. 1.3°C, 24 January
Matsu (Taiwan) min. 0.3°C, 24 January
Onoaida (Japan) min. 0.6°C, 24 January
Okinoerabu (Japan) min. 4.7°C,  24 January
Hitoyoshi  (Japan) min. -9.8°C, 25 January
Okuchi (Japan) min. -15.2°C, 25 January
Ue (Japan) min. -13.8°C, 25 January
Kakutou (Japan) min. -12.0°C, 25 January
Satsuma-Kashiwabaru (Japan) min. -10.8°C, 25 January
Tashiro (Japan) min. -10.4°C, 25 January
Shiroishi (Japan) min. -9.6°C, 25 January
Tokashiki (Japan) min. 3.7°C, 25 January
Itokazu (Japan) min. 4.1°C, 25 January
Izena (Japan) min. 5.2°C, 25 January
Ibaruma (Japan) min. 7.6°C, 25 January
Sibolga (Indonesia) max. 37.1°C,  27 January
(Courtesy of Maximiliano Herrera.)

Three all-time national heat records and one all-time cold record set through mid-February 2016
Just over one month into the year, three nations or territories have tied or set all-time records for their hottest temperature in recorded history in 2016, and one (Hong Kong) has set an all-time cold temperature record. Most nations do not maintain official databases of extreme temperature records, so the national temperature records reported here are in many cases not official. I use as my source for international weather records researcher Maximiliano Herrera, one of the world's top climatologists, who maintains a comprehensive list of extreme temperature records for every nation in the world on his website. If you reproduce this list of extremes, please cite Maximiliano Herrera as the primary source of the weather records. Wunderground's weather historian Christopher C. Burt maintains a database of these national heat and cold records for 235 nations and territories on wunderground.com's extremes page. Here are 2016's all-time heat and cold records so far:

Botswana set its all-time hottest record on January 7, 2016, when the mercury hit 43.8°C (110.8°F) at Maun. The old record was set just the previous day  (January 6, 2016) with 43.5°C (110.3°F) at Tsabong. The record heat in Botswana during the first week of January was part of a remarkable heat wave that affected much of southern Africa, causing at least $250 million in drought-related damages to South Africa in January. Mr. Herrera noted in an email to me that temperatures in South Africa at elevations between 1000 and 1600 meters were higher than any previous temperatures ever recorded at those altitudes anywhere in the world. The national heat records of Lesotho, Mozambique, Namibia, and Swaziland might all have fallen were it not for the lack of observing stations in the hottest areas. Lesotho has no weather stations that issue the standard "synoptic" weather observations every six hours anymore; Mozambique and Swaziland have closed all their stations in the hottest areas; and Namibia just closed its Noordower station, which was its hottest station.

Wallis and Futuna Territory (France) set a new territorial heat record with 35.8°C (96.4°F) on January 10, 2016 at Futuna Airport. This is the second year in a row that Wallis and Futuna has beaten its all-time heat mark; the previous record was a 35.5°C (95.9°F) reading on January 19, 2015 at the Futuna Airport.

Vanuatu in the South Pacific set its all-time national heat record on February 8, 2016, when the mercury hit 36.2°C (97.2°F) at Lamap Malekula. The previous record was a 35.7°C (96.3°F) reading just the previous day (February 7, 2016) at the Bauerfield Efate Airport. All seven major weather reporting stations in Vanuatu beat or tied their all-time heat records February 7 - 8, 2016.

Hong Kong Territory (China) set its all-time coldest mark on January 24, 2016, when the mercury dipped to -5.7°C (21.7°F) at Tai Mo Shan.

We'll have a new post on Friday.

Jeff Masters

Climate Summaries

Springlike Warmth in Southwest U.S., Southeast Europe; Sierra Snowpack Below Average

By: Bob Henson , 7:17 PM GMT on February 16, 2016

Some of the warmest temperatures on record for this early in the year are enveloping large parts of the southwestern United States and southeast Europe this week. The mildness will work its way across the U.S. as the week unfolds, displacing a stormy pattern that’s brought ice and snow to the mid-Atlantic and Northeast and severe weather along the Gulf Coast. NOAA’s Storm Prediction Center logged at least 20 preliminary tornado reports on Monday, mainly from southern Louisiana to the Florida Panhandle, with several injuries reported and several dozen homes, businesses and schools damaged or destroyed. More twisters were reported early Tuesday morning across southern Florida and the Outer Banks of North Carolina. One or more apparent tornadoes inflicted widespread damage to cars and trees across the highly populated area between Miami and Fort Lauderdale at rush hour Tuesday morning. A roundup on weather.com has more on the Monday and Tuesday twisters. The Gulf Coast states are highly prone to severe weather during El Niño, with Florida having double its usual winter risk of tornadoes.


FIgure 1. A mobile home that also served as a day care facility in rural Lincoln County, Miss., was destroyed by a suspected tornado on Monday, Feb. 15, 2016, as severe weather affected south Mississippi. Minor injuries were reported to the adults and children inside. Image credit: The Daily Leader, via AP.


Figure 2. A stormy sunset painted the skies over Ponchatoula, LA, on Mon., Feb. 15, 2016, as heavy thunderstorms moved out of southeast Louisiana. Image credit: wunderphotographer llpj04.


Figure 3. WU observations show the pockets of cold air still trapped in parts of eastern Massachusetts while much milder air was moving in at noon EST Tues., Feb. 16, 2016.


New England says farewell to Arctic air
As quickly as it arrived, the record-cracking Arctic air mass that invaded the northeast U.S. this past weekend is heading out. Temperatures were jumping dramatically on Tuesday as a strong warm front moved north into New England. Below-freezing air was trapped in some river valleys, with readings soaring above 50°F close by. The past day’s patchwork of snow, sleet, freezing drizzle, and freezing rain over eastern New York and New England will be washed away by heavy rain, with widespread 1-2” totals expected.

Despite the ferocity of the Valentine’s Day cold outbreak, temperatures are still above average for the month of February across most of New England and New York (see Figure 4 below). A study in local contrasts: last year Worcester, MA, saw its coldest February in more than a century of record-keeping, yet no daily record lows were set. This past Sunday was the coldest morning Worcester has seen in almost 60 years, with a daily record low of -16°F, and yet the city has a good shot at ending up warmer than average for this February as a whole.

Even with the record lows from Saturday and Sunday taken into account, the year to date has produced more than six times as many daily record highs as daily record lows across the contiguous U.S. (2071 to 335), according to NOAA.


Figure 4. Departures from average temperature (°F), generated from preliminary data for the period Feb. 1 - 15, 2016. Image credit: High Plains Regional Climate Center.


Figure 5. Snow water equivalent (the amount of water held in snowpack) in California’s Sierra Nevada on Tues., Feb. 16, 2016, as a percentage of the average amount observed by April 1 (left values) and by this point in the winter (right values). Image credit: California Department of Water Resources.

Sierra snowpack drops below seasonal average
An unsettling threshold has been crossed in California. After a promising start to the water year, the total amount of water held in snowpack across all three sections of the Sierra Nevada has dropped below the seasonal average (see Figure 5). This number should jump back above average later this week, as a moderately strong Pacific storm moves across California. During the two other El Niños since 1950 as strong as the current one (1982-83 and 1997-98), the Sierra snowpack ended up well above average. However, weaker El Niños have sometimes produced below-average seasonal snowfall. In a typical year, more than 35% of the Sierra snowpack arrives after mid-February, so there is still time for this El Niño to come through. Runoff from the Sierra snowpack produces about 30% of California’s water supply in a typical year.

It’s been an especially dry February thus far in California’s major cities, where moisture for the water year to date (October 1 - present) was running below average across the board as of Monday. This week’s storminess is unlikely to push these values back above average, and long-range models suggest that another warm, dry period in store for next week. The next four to six weeks will be critical in bringing much-needed moisture to Southern California, as precipitation typically tails off rapidly in April. As shown below, Portland and Seattle have been dramatically wetter than California cities relative to the water-year average--in startling contrast to the prototypical El Niño pattern.

San Diego: 6.06” (water year average to date = 6.24”)
Los Angeles Downtown: 4.20” (average 9.10”)
San Francisco Downtown: 13.70” (average 15.77”)
Sacramento: 8.92” (average 11.79”)
Portland, OR: 32.33” (average 20.98”)
Seattle, WA: 35.37” (average 22.91”)


Figure 6. Percent of normal precipitation for the period Feb. 1 - 15, 2016. Image credit: High Plains Regional Climate Center.

Here comes the warm
The mild, dry air mass about to sweep from California across the United States began generating record highs on Monday in downtown Los Angeles (89°F, breaking 88°F from 1985) and San Francisco (77°F, beating 76°F from 1930). A clutch of more impressive records is likely on Tuesday across most of California, and Phoenix may hit 90°F on both Tuesday and Wednesday. The earliest 90°F ever observed in Phoenix was on February 24, 1904. Swarms of record highs can be expected on Wednesday and Thursday as the air mass invades the central U.S., with 70°F air as far north as Nebraska and readings topping 80°F from parts of Kansas southward.

Unseasonable mildness over southeast Europe
Another relatively hot pocket this week is in Europe, where torrid southerly winds from Africa brought temperatures more typical of spring or even summer across eastern Mediterranean islands through the Balkans and beyond. On Monday, the city of Chania on the island of Crete reached a high of 29.2°C (84.6°F)--about the same as a typical day in August. The capital city of Albania, Tirana, reached 25.3°C (77.5°F), and Macedonia’s capital, Skopje (located near the latitude of Boston) reached 24.6°C (76.2°F), close to its monthly record for February. Even parts of eastern Ukraine topped 65°F, approaching 30°F above average. Thanks go to Maximiliano Herrera and Michael Theusner for these data.

Jeff Masters will be back on Wednesday with a full report on January’s global climate.

Bob Henson


Figure 7. High temperatures across Europe for Mon. Feb. 15, 2016. Image credit: OGIMET, courtesy Michael Theusner, Klimahaus Bremerhaven.

Extreme Weather El Niño

Moist Flow Sweeping Out Record Arctic Blast over the Northeast

By: Bob Henson , 10:00 PM GMT on February 15, 2016

A winter’s worth of cold seemed to be stuffed into this President’s Day weekend across the eastern United States. The most frigid air in years--in some places, in decades--swept across much of the Northeast from Friday into Sunday. Borne on strong northwest winds, the Arctic air had little chance to modify, which allowed subzero readings to penetrate virtually all of New England, including Nantucket Island and Provincetown, MA--a rare occurrence even in this chilly corner of the United States. Crisp sunshine allowed a feeble recovery on Sunday, but the bigger shift began on Monday with the gradual organization of a major inland storm. A precipitation shield extending from the mid-Atlantic to New England began as snow but will transition to freezing rain in many areas and eventually to heavy rain by Tuesday, as the freezing line whips northward (it was already through the D.C. area by late Monday). Further south, multiple tornadoes were reported on Monday afternoon along the central Gulf Coast as several supercell thunderstorms spun up within a larger region of severe weather.

The area most at risk of prolonged, serious icing, according to NOAA’s Weather Prediction Center, is a strip from central PA to central NY. West of the surface low, this event should deliver mostly light to moderate snow from the mid-Appalachians across western PA and NY (heaviest over western NY, where more than a foot is possible). As of late Monday, winter storm watches and warnings were plastered from northeast Georgia to Maine.

Meanwhile, Westerners are asking “What winter?”, as springlike conditions work their way eastward from California. Beneath a stout upper-level ridge, southern California is pleasantly warm but unnervingly dry, while forecasters in Phoenix, AZ, are projecting that Wednesday could be the city’s earliest 90°F day on record by a full week.


Figure 1. This striking visible satellite image from Sunday, Feb. 14, 2016, shows cloud streamers forming offshore--the result of instability produced by cold air flowing off the northeast U.S. coast onto warm Atlantic waters. The most prominent streamers are downstream of bays that allow more moisture to be concentrated into the developing bands. Image credit: NASA Worldview, courtesy Tom Niziol, The Weather Channel.

Saturday night in the deep freeze
When a cold air mass invades a region, record-low daytime highs can occur when cloud cover keeps the sun out by day, and clear skies can allow temperatures to plummet to record lows at night once a cold air mass is entrenched. This weekend, the cold air was anything but entrenched: it ripped through the region, which made the arrival and departure of the air mass more important than any local warming and cooling. The depth of the cold air was especially evident at higher elevations. The radiosonde launched at Albany, NY, at 7:00 pm EST Saturday night observed a temperature at the 850-mb level (about a mile above sea level) of -30.8°C (-23.4°F). This was among the lowest readings observed at this height for any Albany radiosonde since routine upper-air observations began in 1948.


Figure 2. Temperature, dew point, and wind chill at the summit weather station operated by the Mount Washington [NH] Observatory on Saturday, Feb. 13, 2016. Readings bottomed out on Saturday evening at -40°F before a steady warm-up began that continued through Sunday and into Monday. (The -40°F reading is not apparent on this trace but was tweeted by MWO.) The last time Mt. Washington was any colder than -40°F was on Jan. 15, 2004, when the site dipped to -45°F. Wind chills on Saturday evening approached -80°F. Image credit: Mount Washington Observatory.


New York City’s major observational sites all set record daily lows on Sunday morning. Central Park made it down to -1°F, while LaGuardia and JFK airports got down to 1°F and Newark hit 0°F. Islip, on central Long Island, made it down to 0°F, the coldest Islip has been outside of January since records began there in 1984. Bridgeport, CT, set a new monthly record low with -6°F; records there began in 1948. Most stations with century-long datasets saw their monthly records unchallenged.

Boston (Logan International Airport) dipped to -9°F on Sunday morning and clawed its way back up to 12°F by evening. As noted by Phil Klotzbach (CSU), those were the coldest daily minimum and maximum temperatures observed so late in the year in Boston since Feb. 15, 1943. The last time Boston and Worcester got as cold as they did on Sunday was in 1957.

We’ll have our next post by midday Tuesday. WU contributor Steve Gregory has a new Monday post that looks in depth at the factors that will bring springlike weather later this week, but with plenty of uncertainty beyond that.

Bob Henson


Figure 3. Low temperatures across southern New England on Sun., Feb. 14, 2016 (degrees °F). Image credit: NWS/Taunton, MA.


Figure 4. From Highland, MI, Jeff Masters reports: “We had our coldest night of the winter Sunday morning, bottoming out at -13°F. The plot from my PWS on Sunday looked remarkably like a step function.”


Winter Weather Extreme Weather

Huge Temperature Swings to Sock the Northeast Ahead of Early-Week Storm

By: Bob Henson , 10:01 PM GMT on February 12, 2016

From frigid, near-record lows this weekend to mild, soggy highs on Tuesday, New York and New England are about to experience one of the most dramatic chill-down-to-warm-up sequences in memory. The brief but sharp cold will extend across the eastern U.S., but the most dramatic temperature swings are expected from Washington, D.C., northward. Some locations from Philadelphia to Portland will rocket from temperatures near or below 0°F on Saturday night--plus much lower wind chills--to readings near or above 50°F by Tuesday.

The weather whiplash is being produced by a highly dynamic pattern that’s pushing cold northerly winds across the region this weekend. As we discussed on Wednesday, this is a deep-layered cold intrusion rather than a shallow, frigid surface air mass. This means that the cold may not set dramatic records at low-elevation towns and cities, but at higher elevations, the chill will be truly exceptional (see below). Because there won’t be a sharp inversion locking in the surface cold air, it will be much easier to scour out than usual. That’s exactly what will happen from Sunday through Tuesday as a strong surface low spins up over the Carolinas and moves northward near the coast, perhaps just inland or just offshore. To the east of the storm, winds will be howling at all levels from the south, pushing in mild maritime air to displace the weekend chill. The orientation of this flow may actually bring milder temperatures to New England than to the mid-Atlantic, accentuating the whiplash effect further north.

The exact track of this storm--impossible to pin down at this point--will dictate how a potpourri of heavy rain, sleet, freezing rain, and snow evolves across the region. The ECMWF model has consistently taken the surface low inland toward central New York, whereas the GFS model has trended further east, but with more run-to-run variation.


Figure 1. Surface air temperatures in °F predicted by the 12Z Friday run of the GFS model for 7:00 am ET on Sunday, February 14, 2016. Image credit: Levi Cowan, tropicaltidbits.com.


Hang on to your hats--and your coats!
As of Friday afternoon, the WU forecasts for major East Coast cities (below) suggest that a few daily record lows might be set on Valentine’s Day (Sunday, Feb. 14). Amazingly, if Boston manages to set a record low on Sunday morning, it will be their first daily record low for the entire month of February in almost 50 years, since -3°F on Feb. 13, 1967 (thanks to Eric Fisher, WBZ, for this tidbit). The potential temperature swings from Sunday to Tuesday are more akin to those felt in dry Western climates!

Predicted low for Sun., Feb. 14, and predicted high for Tues., Feb. 16 (asterisk indicates daily record low)
Portland, ME: -4°F to 43°F (spread of 47°F)
*Boston, MA: -4°F to 50°F (spread of 54°F)
Providence, RI: -6°F to 50°F (spread of 56°F)
Burlington, VT: -4°F, 37°F (spread of 41°F)
*Albany, NY: -11°F to 39°F (spread of 50°F)
Buffalo, NY: -8°F to 36°F (spread of 44°F)
*New York, NY (Central Park): 0°F to 50°F (spread of 50°F)
*Philadelphia, PA: 0°F to 47°F (spread of 47°F)
Washington, DC (National): 10°F to 47°F (spread of 37°F)



Figure 2. As shown by this Wundermap, temperatures at the 850-mb level (about a mile above ground) projected by the 12Z Friday run of the GFS model for Saturday night (top) will drop below -30°F in places. This will be close to the lowest ever observed by radiosonde across parts of the Northeast. The yellow region over the Adirondacks corresponds to predicted values colder than -29°F about a mile above sea level at 10:00 pm EST Saturday, Feb. 13, 2016. Less than three days later (bottom), at 7:00 pm EST Tuesday, Feb. 16, readings at this altitude may soar above 46°F over southern New England.


Radiosondes may provide our most impressive benchmark of this weekend’s cold event. In the soundings to be launched at 0Z Sunday (7:00 pm Saturday), the temperatures at 850 mb (about a mile above sea level) may challenge February record lows at New York and Boston, in data going back to 1948. Buffalo has a shot at its monthly 850-mb record low on Saturday morning, and on Saturday night, Albany could break its all-time coldest radiosonde-measured 850-mb temperature (current record -31.8°C, interpolated from data on Feb. 8, 1963; thanks to Patrick Marsh, NOAA Storm Prediction Center).

Weather pick of the weekend: Mt. Washington, New Hampshire
There aren’t many weather stations at high altitude over the Northeast, but those that exist will get a wintry hammering this weekend. The most venerable of these is atop Mount Washington, NH (elevation 6289 feet), where the Mount Washington Observatory was established in 1932. The MWO’s Friday afternoon forecast for higher summits in the region is a jaw-dropper: “Temperatures will fall steadily into Saturday night where they will bottom out in the mid 30’s below zero....The coldest air and the highest winds will likely occur at the same time so wind chills late Saturday into Saturday night will be approaching 90 below zero. These are extremely dangerous conditions to be exposed to for any length of time.” Winds are expected to gust as high as 95 mph.

The MWO station dipped to -35°F three times in February 2015. The last time a colder temperature was recorded was -37°F on February 6 and March 6 of 2007, according to Mike Carmon, co-director of summit operations. The most recent temperature below -40°F was -45°F on January 14 and 15, 2004. “We do not keep records of wind chills at the summit, being that they are constantly-fluctuating and calculated values,” Carmon told me in an email. “Off the top of my head, though, I can say the last time we hit wind chills approaching -90F was almost exactly one year ago during the President’s Day polar outbreak of 2015.”

The coldest temperature ever observed at the summit actually predates MWO. A U.S. Signal Service station that operated sporadically from the 1870s to 1890s reported a low of -50°F on Jan. 22, 1885, according to the Northeast Regional Climate Center. This reading is not yet reflected in NOAA’s digital data files but exists in NOAA archives.


Figure 3. The Mount Washington Observatory, encased in rime ice on April 7, 2004. Image credit: Talinus/Wikimedia Commons.

Other all-time records at higher-altitude stations across the Northeast also date back many decades. They include:

Pinkham Notch, NH (2010 ft): -32°F on 2/16/1943
Mt Mansfield, VT (3950 ft): -39°F on 1/9/1968 & 1/15/1965 & 1/15/1957
Lake Placid, NY (1940 ft): -39°F on 12/30/1917
Whiteface Mtn., NY (4865 ft): -36°F on 1/25/1945 (period of record is 9/1937-8/1946)
North Lake, NY (1831 ft): -47°F on 2/9/1934 (period of record is 9/1896-5/1948)
Slide Mtn., NY (2650 ft): -23°F on 1/18/1982 (period of record is 12/1961-10/2012)
(Thanks to Jessica Spacio at the Northeast Regional Climate Center for these data.)

Meteorologist Anton Seimon (Appalachian State University/University of Maine) got a taste of high-altitude Northeast cold on a ski trip in mid-January 1994 to Lake Colden, NY (elevation 2762 feet). “On that Saturday night [Jan. 22], our mercury thermometer spent several hours parked at -45°F (-42.7°C) while winds in the strongly channeled lake corridor gusted to about 25 knots with blowing snow.” Seimon said in an email. “We did measure even colder temperatures in the central Adirondacks on other excursions during that winter, but those were under calm, radiative cooling conditions. In terms of pure cold and wind chill, the 1994 Lake Colden night remains the superlative event in my recollection.”

We’ll be back with another post by Tuesday morning at the latest. Have a great President’s Day weekend, and stay warm!

Bob Henson

Extreme Weather Winter Weather

A Mostly Mild and Dry January for U.S., Punctuated by Big Storms

By: Bob Henson , 4:56 PM GMT on February 11, 2016

The strong El Niño event dubbed “Godzilla” by one oceanographer behaved more like a hero than a monster in January, at least when it came to conditions across the United States. Mild and dry weather prevailed over much of the nation, and where it was wet or snowy, the moisture was generally well predicted and widely appreciated, apart from a titanic Northeast snowstorm (see below).

Last month was the 34th warmest and 36th driest January for the contiguous U.S., according to the roundup released on Wednesday by the NOAA National Centers for Environmental Information (NCEI). The stark west-to-east temperature contrasts that prevailed during January 2013, 2014, and 2015 were absent this time around. Instead, there was a more muted contrast between relative mildness over the West and Northeast and below-average readings across the Southeast. This matches well with the typical outcome in January during strong El Niño events. The month’s overall mildness shows up in the lopsided 4-to-1 ratio of daily record highs to daily record lows (646 to 156).


Figure 1. State-by-state temperature rankings for January 2016. The rankings go from warmest (122) to coldest (1) for the 122 years of record-keeping from 1895 to 2016. This year, none of the contiguous U.S. states had a top-ten warmest or coldest January. Image credit: NOAA/NCEI.


Figure 2. State-by-state precipitation rankings for January 2016. The rankings go from wettest (122) to driest (1) for the 122 years of record-keeping from 1895 to 2016. This year, Florida had its fourth wettest January on record, and Ohio had its ninth driest. Image credit: NOAA/NCEI.


Florida and the West win the precipitation sweepstakes
Northern states are typically drier than average in a strong El Niño--especially the Ohio Valley--and that was the case in January, with the state of Ohio recording its ninth driest January on record (see Figure 2). But the dryness extended well southward across the Southern Plains and Southeast, regions that are typically moister than average during major El Niños. Florida is one place where the wet expectations from El Niño were more than met, as a potent and persistent subtropical jet helped the state notch its fourth wettest January on record. It was the wettest January ever observed in Fort Myers (12.98”) and Vero Beach (9.39”) and the second wettest in Miami (7.57”).

Moisture was also plentiful across the southwest U.S., again in line with the pattern from previous strong El Niños. The focus in California was on the northern two-thirds of the state, where several locations scored 150% to 200% of their average January precipitation. Snowpack across the Sierra Nevada--crucial for summer water supplies--grew to 113% of average by the end of January, the first above-normal value in January since 2011. Generous snowfall extended east across parts of the central and southern Great Basin, again typical of El Niño. In a more unexpected wrinkle, heavy rains and snows pushed all the way north to Washington, where El Niño midwinters tend to skew dry. With 7.45” of rain in January following 11.21” in December, Seattle ended up with its wettest December-January period on record.

According to the January 2016 Catastrophe Report from insurance broker Aon Benfield, El Niño-fueled Pacific storms that brought heavy rainfall, snow and isolated severe weather to portions of California in early January caused flooding, mudslides and debris flows that cost at least $125 million. For comparison, El Niño storms during the great 1997 - 1998 El Niño caused nearly $500 million in damage to the state.

Among the noteworthy dry spots were Honolulu, Hawaii (second driest January on record, with 0.03” of rain); Fairbanks, Alaska (tied for driest, with only 0.01” of precipitation); and Jamestown, North Dakota (driest on record, with just a trace). All three locations have a dry tendency during El Niño midwinters.


Figure 3. The rising sun illuminates a snow-covered scene in front of the White House on January 26, 2016, in Washington, D.C. Image credit: Mark Wilson/Getty Images.


Figure 4. A woman attempts to dig her car out from beneath heavy snow in the Columbia Heights neighborhood of Washington, D.C., on Tuesday, January 26, 2016, following the weekend blizzard. Image credit: Chip Somodevilla/Getty Images.

Weather whiplash to the max: Balmy, then buried
A wrenching shift in weather occurred across the mid-Atlantic and Northeast on the weekend of January 22-24, when a previously tranquil month for millions of residents was interrupted by a ferocious, city-blanketing nor’easter that was dubbed Winter Storm Jonas by the Weather Channel. The region was just coming off record-smashing warmth during the end-of-year holidays. Jonas arrived only a few days after Philadelphia and Washington, D.C., had gotten their first flakes of snow for the winter--on January 12, a record-late date for both cities.

According to NCEI, eight of the 35 major airport weather stations in the Northeast received their heaviest single-day snowfall on record on January 23. Storm totals exceeded 25” from parts of Virginia to New York (see Figure 5 below). With some of the heaviest snow focused on the urban corridor from Washington to New York City, Jonas ended up ranked as the fourth most impactful snowstorm of the last 66 years in the Northeast Snowfall Impact Scale (NESIS), which takes into account the area and the number of people affected by a snowstorm as well as the amount of snow that fell.

The intensity of this blizzard was evident days ahead of time, and the storm’s arrival on a weekend helped reduce its impact. Still, Jonas caused at least $2 billion in losses, according to insurance broker Aon Benfield. At least 55 deaths were reported, many from traffic accidents or from heart attacks induced by shoveling snow.


Figure 5. Snowfall accumulations during the Megapolitan storm of Feb. 10-12, 1983 (left) and the blizzard of Jan. 22-24, 2016 (right). Image credit: NOAA/NCEI.

It’s happened before: Epic Northeast snow during a strong El Niño
As Jon Erdman explains in a comprehensive weather.com article, some of the snowiest winters across the Northeast have occurred when El Niño is accompanied by a predominantly negative North Atlantic Oscillation (NAO). This combo allows Arctic air to mix it up with moisture-laden flow from the tropics and a powerful subtropical jet stream. Though the NAO has mostly been in a positive mode this winter, it briefly turned negative in mid-January, just before Jonas arrived.

There’s an excellent historical precedent for a record-burying Northeast snowstorm in the midst of an otherwise placid El Niño winter. The “super” El Niño of 1982-83 was largely free of major winter storms across the Northeast, except for the memorable Megapolitan blizzard of February 10-12, 1983. Figure 5 shows the similarity between the 1983 and 2016 events. Both storms were followed by a rapid meltoff, especially in the D.C. area, where highs climbed well into the 40s and 50s for at least 10 days after each storm cleared out.

We’ll be back with a new post by Friday afternoon.

Bob Henson




Climate Summaries

Northeast Braces for a Frigid, Windy Weekend

By: Bob Henson , 6:04 PM GMT on February 10, 2016

A quick but intense shot of blustery cold will sweep across the northeast U.S. this weekend, reminiscent of the “polar vortex” outbreaks from the last two winters. Compared to the multi-day blasts of cold that were common in early 2014 and 2015, this will be more of a glancing blow, but stout breezes will push wind chills far below zero in many areas.


Figure 1. Surface air temperatures in °F predicted by the 12Z Wednesday run of the GFS model for 7:00 pm ET on Saturday, February 13, 2016. Image credit: Levi Cowan, tropicaltidbits.com.

The brief blast of Arctic chill is partially an offshoot of rapid changes in the Arctic stratosphere. Temperatures there shot up to near-record highs this week, scrunching the stratospheric polar vortex toward Europe. An equally quick cool-down is expected over the next week or two, which should allow the vortex to shift toward its more typical position centered near the North Pole. Meanwhile, the flow at lower levels will remain northerly from polar regions into the eastern United States, and a sprawling surface high will push from the Canadian Arctic all the way into the U.S. Northeast by the weekend.


Figure 2. Wundermap depiction of wind speeds at the 250-mb jet-stream level (about 34,000 feet above sea level) at 06Z (1:00 am EST) Wednesday, February 10, 2016. Winds are shown in knots; multiply by 1.15 for miles per hour.

Basking in February warmth
Another player is the strong upper-level ridge that’s forcing the jet stream from the eastern Pacific to split before it reaches the coast. This ridge--more akin to the Ridiculously Resilient Ridge of the last several winters than to a classic El Niño pattern--has brought sunshine and extremely mild weather throughout the U.S. West, shutting down winter rainfall. Temperatures on Tuesday soared to 85°F at Monterey, California, and into the 90°F range across the Los Angeles area. Santa Ana’s toasty high of 95°F tied its monthly record for February.

In Washington state, upper-level readings were the warmest for February in more than 60 years of recordkeeping (see Figure 3). The mildness at elevation led to “one of the strongest inversions I have ever seen here in Seattle,” said longtime resident Cliff Mass (University of Washington) in his weather blog. It was a full 23°F warmer just 1640 feet above Seattle (less than the height of the world’s tallest skyscrapers) than in the city itself. Sea-Tac Airport ended up setting a record high of 63°F, but just by one degree.


Figure 3. The view from atop Seattle’s Space Needle on Tuesday morning, February 9, 2016, showing the fogged-in city overtopped by sunny, milder air. Image credit: Space Needle Cam, courtesy Cliff Mass.


Figure 4. Since 1948, radiosondes have measured temperature at upper levels of the atmosphere. Shown here are daily readings at the 850-mb level (about a mile above ground) for Quillayute, WA, near Seattle. Record highs and lows for each date are shown by red and blue traces respectively. The temperature of 16.6°C (61.9°F), recorded at 12Z Tuesday, February 9, 2016, and shown in the black dot, was the warmest observed above Quillayute for any February or March day on record. At the surface, Quillayute’s high of 73°F on Tuesday tied the record high for February, in data going back to 1966. Image credit: NOAA Storm Prediction Center and Cliff Mass.

Record cold aloft on its way--but at the surface, not so much
This weekend is likely to see some of the coldest air ever observed aloft over the Northeast in the 60-plus-year period with radiosonde data available (beginning in 1948). Temperatures at the 850-mb level, about a mile above ground, are projected to tumble by Saturday to readings as low as -32°C above Buffalo, NY, and -30°C over Burlington, VT, with even colder readings possible over the Adirondacks (see Figure 5). The Buffalo temperature at 850 mb would be on par with the all-time low from the radiosonde dataset.

But the surface air mass cascading southward from Canada doesn’t fully mirror the coldness that’s present higher up, and it won’t be strong enough or long-lasting enough to allow surface temperatures to plummet as they otherwise might. While it’ll be unquestionably frigid this weekend in the Northeast, there will be few if any monthly record lows at the surface, and even daily record lows may be hard to come by. For example, at Burlington, VT, the current WU-predicted high of 3°F on Saturday and low of -8°F on Saturday night would fall well short of the record low maximum for Saturday (-3°F, from 1979) and the record low for Sunday morning (-19°F, from 1987). Compare this to last week in Burlington, when record daily highs were set on four consecutive days (Feb. 1 through 4). Of course, those highs—which included 54°F on Feb. 3 and 4--were far more pleasant and less extreme-feeling than what Burlington will experience this weekend.


Figure 5. As shown by this Wundermap, temperatures at the 850-mb level (about a mile above ground) projected by the 06Z Wednesday run of the GFS model will be close to the lowest ever observed by radiosonde across parts of the Northeast. The yellow region over the Adirondacks corresponds to predicted values colder than -34°C (-29°F) about a mile above sea level at 10:00 pm EST Saturday, February 12, 2016.

A teeth-chattering flashback
Like the strong ridge in the West, this weekend’s cold pattern in the Northeast will serve as a brief echo of the last several winters. In early 2015, recurrent upper-level troughs and back-to-back-to-back snowfall led to weeks of misery in Boston and gave New York and Vermont their coldest January-to-March period on record. Still, the readings that winter weren’t so much brutally low as consistently low.

“In Boston, we haven’t seen a temp colder than -3°F since 2004 (when we hit -7F),” noted weathercaster Eric Fisher (WBZ/WSBK). “The coldest we could manage last winter was -3°F, and we didn’t set a single daily record low. The cold was more of the extremely persistent kind than the one-off shocking variety.” Fisher added that Boston has seen only nine subzero nights in the last 20 years. The latest WU forecast brings Boston down to –4°F by Sunday morning.

Wind chills will add to the impact of this weekend’s fierce cold, especially in the wake of what’s been a quite mild winter overall. Wind chill readings in the range of -10°F to -20°F may spread across the Boston area on Saturday night. The windiness is a hint that this frigid air mass isn’t planning to hang around for long. By Monday, return flow from the south will be putting a significant dent in the cold. Temperatures will be back to near the seasonal average by Tuesday, but still cold enough to pose a potential winter weather hazard as low pressure organizes near the mid-Atlantic coast early next week. The brunt of this nor’easter may end up offshore, but as with several recent storms, coastal areas could easily get slapped with heavy, windblown snow--or heavy rain, if temperatures recover quickly enough. Freezing rain and/or sleet may also become a concern over the mid-South if enough mild air is wrapped around the developing nor’easter. Models are still struggling with this storm, but it’s certainly one to watch.


Figure 6. The expected Northeast cold stands out amid unusually warm temperatures almost everywhere else in this hemispheric map of projected surface temperatures relative to seasonal averages at 03Z Sunday, February 14, 2016 (10:00 pm EST Saturday). The map is based on the 18Z Wednesday run of the GFS model. Image credit: Climate Reanalyzer/University of Maine.

More to come?
Long-range forecasters are debating whether the Northeast is likely to see many more rounds of intense cold this winter. Judah Cohen (AER) expects relatively cold readings to predominate from late February into March across the midlatitudes of North America and Eurasia. “The perturbation of the [polar vortex] is likely to dominate the evolution of the temperature variability across the Northern Hemisphere (NH) for the duration of winter,” said Cohen in a February 8 blog post.

This outlook would be in line with the tendency in recent years toward intense winter cold outbreaks in northern midlatitudes, including the northeast U.S.--a development that Cohen and others have associated with depleted Arctic sea ice. However, it would run counter to the typical outcome during strong El Niños of relative mildness across the northern U.S. and Canada. WU blogger Steve Gregory sees the El Niño signal returning full force within a few days, perhaps assisted by a favorable phase of the Madden-Julian Oscillation. “While it is still far from a certainty, we should see a return to above normal temps in the east and below normal in the west, along with increased chances of precip along the west coast in about 10 days,” Gregory said in a Monday blog post.

We’ll have our next post by Thursday evening.

Bob Henson

Extreme Weather Winter Weather

Hurricane Patricia's 215 mph Winds: A Warning Shot Across Our Bow

By: Jeff Masters , 5:12 PM GMT on February 08, 2016

The Eastern Pacific's Hurricane Patricia--rated the strongest hurricane ever recorded in the Western Hemisphere with 200 mph sustained winds on October 23, 2015--was actually much stronger, with 215 mph winds, said the National Hurricane Center (NHC) last week, after completing a detailed post-season review. An Air Force hurricane hunter aircraft measured a surface wind of 209 mph in Patricia at 0600 UTC October 23 using a Stepped-Frequency Microwave Radiometer (SFMR); this was the highest surface wind ever measured in a tropical cyclone, worldwide, since the technology was introduced in the mid-1980s. A 207 mph surface wind was measured by the SFMR instrument on a NOAA hurricane hunter aircraft during an eyewall penetration about twelve hours later, at 1732 UTC. In between those two times, there were no measurements by the Hurricane Hunters, but satellite imagery showed that the hurricane improved in organization up until about 1200 UTC, with the eye warming and the eyewall cloud tops cooling. NHC thus assigned Patricia a peak intensity of 215 mph winds with a central pressure of 872 mb at that time. Hurricane Patricia's 215 mph winds officially tie it with the Northwest Pacific's Super Typhoon Nancy of 1961 for strongest winds of any tropical cyclone in world history, and Patricia's lowest pressure of 872 mb makes it the second most intense tropical cyclone in world history, behind the 870 mb measured in the Northwest Pacific's Super Typhoon Tip of 1979 (Tip's top sustained winds of "only" 190 mph were not as high as Patricia's, since Tip was a large, sprawling storm that did not have a tiny concentrated area of extreme eyewall winds.) Note that that the maximum sustained winds estimated in typhoons like Nancy during the 1940s to 1960s are considered by hurricane experts to be too strong; a re-analysis of Super Typhoon Nancy would likely find that its winds were considerably slower than 215 mph. I regard Patricia as unmatched for the strongest winds of any tropical cyclone in recorded history. It is possible that previous hurricanes where hurricane hunter flights were not available, such as the Category 5 1935 Labor Day hurricane that devastated the Florida Keys, had peak winds on par with Patricia, though.


Figure 1. Hurricane Patricia as seen by the MODIS instrument on NASA's Terra spacecraft at 1:30 pm EDT (17:30 UTC) October 23, 2015. At the time, Patricia had 205 mph sustained surface winds and a central pressure of 878 mb. Patricia had peaked at 215 mph sustained winds and a central pressure of 872 mb six hours previously. Image credit: NASA.


Figure 2. Category 5 Hurricane Patricia as seen from the International Space Station on Friday afternoon, October 23, 2015. Image credit: Commander Scott Kelly.

Patricia the fastest- to second-fastest-intensifying Western Hemisphere hurricane on record
In the 24-hour period ending at 2 am EDT (06 UTC) October 23, 2015, Patricia's central pressure dropped an astonishing 95 mb, to 886 mb, and the winds increased by 120 mph, to 205 mph, making Patricia the fastest-intensifying hurricane (by winds) and second-fastest intensifying hurricane (by pressure) ever observed in the Western Hemisphere. The record pressure drop in 24 hours is 97 mb for Hurricane Wilma of 2005 (between 1200 UTC 18 October - 1200 UTC 19 October), and the previous record intensification of winds in 24 hours was 110 mph for Wilma, according to the official NHC report for the storm. Patricia's intensification rate was very close to the WMO-recognized world record for fastest-intensifying tropical cyclone: 100 millibars in just under 24 hours by Super Typhoon Forrest in the Northwest Pacific in 1983.

Another remarkable record: a NOAA reconnaissance aircraft flying through the eye at 17:33 UTC October 23, several hours after the time of estimated peak intensity, measured a maximum 700-mb temperature of 32.2°C (90°F). This is the warmest 700-mb eye temperature ever measured in a tropical cyclone world-wide. The height of the 700 mb level was 2043 meters (about 6700 feet) above sea level, which is the lowest such height ever observed in the tropics in the Western Hemisphere. A more typical height for the 700 mb pressure level is 3180 meters (10,430 feet.) Since hurricane penetrations are done by flying the aircraft at a constant pressure altitude of 10,000 feet (in other words, flying so that the aircraft is continuously experiencing a pressure of approximately 700 mb), the aircraft had to make a steep descent while traversing the eyewall in order to stay at the 700 mb pressure level, and emerged into the eye at an altitude as measured by radar that was below 7,000 feet. The steep descent caused trouble with the SFMR readings, which had to be re-calibrated after the flight to ensure their accuracy. Thanks go to Rich Henning of the NOAA Hurricane Hunters for this info.


Figure 3. Ten-day averaged sea surface temperatures (SSTs) from 1948 - 2015 during mid-October over the waters of the Eastern Pacific off the coast of Mexico between 13°-17°N and 100°-105°W (inset box) traversed by Hurricane Patricia during its rapid intensification period October 20 - 23, 2015. SSTs were at their highest values on record in this region in 2015. Image credit: NHC.

Patricia's record intensification fueled by record-warm ocean waters
Hurricane Patricia's remarkable intensification was made possible by very light wind shear and record warm ocean waters. During its rapid intensification phase, Patricia tracked over a large expanse of anomalously warm waters with sea surface temperatures (SSTs) of 30.5°-31°C (87°-88°F). These were the highest SSTs ever observed over this region in mid-October.


Figure 4. Wind (black) and surface pressure (red) from the afternoon NOAA hurricane hunter flight on October 23, 2015 into Hurricane Patricia, off the Pacific coast of Mexico. The aircraft measured peak winds at their flight level of 10,000 feet of up to 145 knots (165 mph). The winds showed a double maximum in both sides of the eyewall as the plane flew crossed the calm eye, indicating that an eyewall replacement cycle was likely underway. This eyewall replacement cycle helped Patricia become the fastest-weakening hurricane ever observed. The eye was a tiny 6 miles in diameter at this time. Image credit: Levi Cowan, tropicaltidbits.com.

Patricia the fastest-weakening Western Hemisphere hurricane on record
As Patricia approached the rugged Mexican coast, the storm began to weaken due to two major factors: interaction with land, and an eyewall replacement cycle. Patricia’s central pressure is estimated to have risen a remarkable 54 mb in the five hours prior to landfall. No other tropical cyclone over water in either the Atlantic or Eastern North Pacific historical record has been observed to weaken so quickly. Patricia made landfall near 23 UTC October 23 along a sparsely populated part of the coast of southwestern Mexico at Playa Cuixmala, about 50 miles west-northwest of Manzanillo, as a category 4 hurricane with 150 mph winds and an estimated landfall pressure of 932 millibars. This makes Patricia the strongest hurricane on record to make landfall in Mexico, eclipsing the October 1959 Manzanillo hurricane (recently reassessed to have made landfall at category 4 intensity), and Hurricane Madeline in 1976. Note, though, that reliable records for extreme landfalling Mexican hurricanes extend back only to 1988. Only two direct deaths were reported from Patricia's landfall, but damage was a steep $325 million.

Hurricane Hunters measure near-record updrafts and downdrafts
NOAA's hurricane hunter aircraft N43RF ("Miss Piggy") encountered significant turbulence (3 Gs of acceleration in the cockpit) both inbound and outbound from the 1733 UTC October 23 eye fix into Patricia. The aircraft measured a peak updraft of +26.1 m/s (58 mph) and a downdraft of -16.2 m/s (36 mph). Thanks go to Rich Henning of the NOAA Hurricane Hunters for this info. To my knowledge, this is the strongest downdraft ever recorded in a hurricane by the NOAA P-3 Orion Hurricane Hunter aircraft since they began service in 1976. According to an email I received from hurricane scientist Sim Aberson at NOAA's Hurricane Research Division, the only higher updraft ever measured by the P-3s is probably the 31 m/s (69 mph) reading in Category 5 Hurricane Felix of 2007 in the Caribbean. The extreme turbulence associated with this updraft (and the downdraft of 11 m/s or 25 mph that immediately preceded it) forced the aircraft to abort the mission and return to base. The only two other NOAA hurricane hunter flights with comparable extreme updrafts and downdrafts were into Hurricane Emily of 1987 and Hurricane Hugo of 1989. I was the Flight Meteorologist on both flights. Flying at 15,000 feet in Category 3 Hurricane Emily as it was making landfall in Hispaniola, we observed 3 Gs of acceleration during an updraft of +23.9 m/s (53 mph) that was accompanied by a downdraft of -9.6 m/s (21 mph). During this penetration through the eyewall, pilot Jim Gunoe was forced to roll the plane about 20 degrees in order to stop a dangerous aerodynamic flutter that developed in the wings. We then aborted the mission due to the extreme turbulence. Two years later, flying at 1,500 feet into the eyewall of Hurricane Hugo, we hit 5.7 Gs of acceleration as we measured a +21 m/s updraft and -8 m/s downdraft. An engine flamed out during this extreme turbulence, and the pilot was able to pull us out of a steep descent just 880 feet above the waves as we entered the eye. This flight was the subject of a detailed story that I wrote and a 45-minute long video by the TV series, Air Crash Investigation that aired on the National Geographic Channel last year (complete with CGI graphics and actors playing the roles of the crew.) The video is available on YouTube.

The Air Force Hurricane Hunters have encountered similar extreme updrafts and downdrafts in some of their flights into Category 5 hurricanes, such as into Hurricane Wilma of 2005 when it was at peak intensity, but the vertical wind data taken from the Air Force C-130 hurricane hunter aircraft are not routinely analyzed post-flight.


Figure 5. Infrared VIIRS images of Hurricane Patricia near peak strength: 215 mph winds and a central pressure of 872 mb. Image credit: Dan Lindsey, NOAA.

Another record: worst NHC intensity forecast ever made in the Eastern Pacific
As one might expect when trying to forecast the intensity of a hurricane that smashed all previous intensification records in mind-boggling fashion, NHC's intensity forecasts for Patricia were way off. The average error in NHC 48-hour intensity forecasts was 66 mph, compared to an average forecast error of 16 mph for all Eastern Pacific forecasts made during the 2010 - 2014 period. Several of NHC's forecasts for Patricia had intensity errors through 48 hours that were the highest on record since NHC took over warning responsibility in the eastern North Pacific basin in 1988: up to 120 mph off, beating the record 115 mph error for a forecast made in Hurricane Linda of 1997. None of the intensity models anticipated the degree to which Patricia would intensify, nor how quickly it would occur, and the official intensity forecasts for Patricia from NHC severely underestimated the rapid intensification that occurred and failed to explicitly show rapid intensification until it was actually occurring. It should be noted, however, that a key model used to make intensity forecasts--the SHIPS Rapid Intensity (RI) guidance--was temporarily unavailable before Patricia’s rapid intensification began due to missing satellite inputs. Having these data in real time would likely have resulted in better intensity forecasts than those that were made.


Figure 6. Expected change in Atlantic Category 4 and 5 hurricanes per decade expected by the year 2100, according to Knutson et al. (2013), "Dynamical Downscaling Projections of 21st Century Atlantic Hurricane Activity: CMIP3 and CMIP5 Model-based Scenarios." This research used the latest generation of climate models from the 2013 IPCC report, and found "marginally significant" increases in Atlantic Category 4 and 5 hurricanes of 39% - 45% by 2100.

Commentary: Patricia was a warning shot across our bow
Consider, now, if the bad intensity forecasts for Hurricane Patricia had been made for a Hurricane Patricia clone that had ended up making landfall in a heavily populated area such as Miami, Galveston/Houston, Tampa, or New Orleans, but without the hurricane weakening dramatically at landfall. A 15-mile diameter area of 215 mph winds--EF5 tornado speeds--would have caused near-total destruction. Since the storm would have been significantly under-warned for, a full evacuation might not have been completed, resulting in one of the deadliest hurricane tragedies in human history. The ten-year drought in major hurricane landfalls in the U.S. is going to end someday, and an onslaught of major hurricanes like we experienced in 2004 - 2005--seven landfalls by major hurricanes in two years--could happen again. As I discussed in my 2013 post, Hurricanes and Climate Change: Huge Dangers, Huge Unknowns, the consensus among hurricane experts is that climate change is likely to bring an increase in the number of high-end hurricanes like Patricia. Now that ocean temperatures are considerably warmer than they were a few decades ago, the maximum potential intensity a hurricane can reach is higher, and we should expect to see a few Patricias sprinkled among the inevitable phalanxes of major hurricanes that will assault our shores in the coming decades.

Progress is being made in improving hurricane intensity forecasts, thanks to the 10-year Hurricane Forecast Improvement Project (HFIP), which aims to reduce hurricane track and intensity errors by 50% by 2019. Unless some dramatic breakthroughs in intensity forecasting occur in the next three years, though, we are going to fall short of that goal. But if we really want to crack the intensity forecast puzzle, we should be spending far more on hurricane research than we do--something I've been calling for repeatedly over the past ten years. The National Science Board, in a report issued in 2006, called for an increase of $300 million per year in hurricane research funding. That's more than ten times the annual spending on hurricane research of $20 - $25 million per year that we've averaged over the past ten years. The 24 members of the National Science Board are appointed by the President of the United States, and make budget recommendations for the National Science Foundation (NSF). They are not prone to make frivolous budgetary recommendations, and realize that the specter of a Patricia-like nightmare storm hitting with insufficient warning is one to take seriously. Such a large but sensible investment can lead to significantly better intensity forecasts. Will we wait again to see unprecedented mayhem like during Katrina in 2005 and Sandy in 2012 before responding to the need to spend more money on better hurricane forecasts? Consider Patricia a shot across our bow--we have been warned (again.) It is up to us to respond.

Hurricane Patricia Cat-5 fix

Check out this incredible footage of our flight through the eye of Category 5 Hurricane #Patricia off the coast of Mexico. The video was taken from the flight station of #NOAA43 (#NOAA P-3) and provided by Lt. Cmdr. Scott Price (the missions's Aircraft Commander). The video begins inside the eyewall: note that the intense rain and wind combination makes it impossible to see the nose of the aircraft just a few feet away. At 37 seconds, the crew enters the eye of the #Hurricane, where the violent sea-state below becomes visible. Note that due to the storm's incredibly steep gradient, the aircraft is pitched downward as the aircraft descends closer to the ocean. At 57 seconds, the curved eyewall on the opposite side of this very small eye becomes apparent. After a couple of slight turns requested by the Flight Meteorologist to report the exact center of the storm, the crew turns right to avoid the worst of the eyewall. At ~2 minutes into the video, the aircraft reaches the opposite eyewall where the crew loses visibility once again.

Posted by The NOAA Hurricane Hunters on Thursday, November 5, 2015


Video 1. Incredible footage the flight of NOAA hurricane hunter aircraft N43RF through the eye of Category 5 Hurricane Patricia on the afternoon of October 23, 2015, when the storm was near peak strength, with 205 mph sustained surface winds and a central pressure of 878 mb. Lt. Cmdr. Scott Price (the mission's Aircraft Commander) made the video using a GoPro camera. The video begins inside the eyewall: note that the intense rain and wind combination makes it impossible to see the nose of the aircraft just a few feet away. Since the aircraft is flying perpendicular to the wind in order to find the center, the rainfall is blowing from left to right in front of the pilot's vision. At 37 seconds, the crew enters the eye of the hurricane, where the violent sea-state below becomes visible. Note that due to the storms incredibly steep pressure gradient, the aircraft is pitched downward as the aircraft descends closer to the ocean, in order to keep flying at a constant pressure altitude. At 57 seconds, the curved eyewall on the opposite side of this very small eye becomes apparent. After a couple of slight turns requested by the Flight Meteorologist to report the exact center of the storm, the crew turns right to avoid the worst of the eyewall. At ~2 minutes into the video, the aircraft reaches the opposite eyewall where the crew loses visibility once again. Posted by The NOAA Hurricane Hunters on Thursday, November 5, 2015.

Jeff Masters

Hurricane Climate Change

Five Weathercasters Who Made History

By: Bob Henson , 5:05 PM GMT on February 05, 2016

Happy National Weatherperson’s Day! This American holiday takes place each year on February 5, the birthdate of John Jeffries (1745-1819). Jeffries was a military surgeon during the American Revolution, and later the family physician to future President John Adams, but he gained his greatest meteorological fame by taking observations from a hot-air balloon above London.

To salute the occasion, I thought I’d spotlight a tiny sample of the hundreds of Americans who made their mark as weathercasters in the first several decades of TV. Shameless plug: these pioneers are drawn from among dozens featured in my book ”Weather on the Air: A History of Broadcast Meteorology” (AMS Books).

s
Figure 1. Harry Volkman at WGN in 1979 or 1980, just before computer graphics came into widespread use in weathercasting. Image credit: Wikimedia Commons.

Harry Volkman
When TV was getting its sea legs in the early 1950s, tornado warnings were largely banned from the airwaves. The U.S. Weather Bureau was experimenting with their use at military bases but was worried they might panic the public. At Oklahoma City’s WKY-TV (now KFOR), weathercaster Harry Volkman took a risk and aired what was apparently the first-ever public tornado warning (pinched from nearby Tinker Air Force Base) in March 1952. Instead of triggering panic, the warning drew more than 1,600 cards and letters of gratitude. One read: “We breathe a sigh of relief knowing you are on the job. God bless you.” By the late 1950s, Volkman had moved to Chicago, where he remained on the air until retiring in 2004. He died last August at the age of 89. Here’s a wonderful tribute to Volkman from an Emmy Award ceremony, including clips from throughout his career, and a classic 1967 weathercast in which Volkman apologizes profusely for having blown his forecast of a major snowstorm.



Figure 2. Tedi Thurman in a publicity still for NBC’s “Monitor” radio program.

Tedi Thurman
Women made huge inroads into weathercasting in the 1950s, but far too often they were boxed into “weathergirl” roles. Tedi Thurman achieved much within this outlandishly sexist system by combining her interests in art, fashion, and weather. She became America’s best-known female weathercaster--probably “the most recognizable female voice in the country,” said historian Dennis Hart--with the 1955 debut of NBC’s “Monitor” radio show, a talk/variety marathon that ran every weekend. Thurman wrote and produced her weather segments, gathering data from the Weather Bureau and spotlighting cities around the country based on current events and her own interests. In 1957, Thurman made several appearances on NBC’s “Tonight” show, then hosted by Jack Paar. She left “Monitor” and weathercasting in 1961 but later spoke fondly of those days: “We were heard all over the world and admired by audiences who came by our glass-enclosed studio, Radio Central. It was awesome.” Thurman died in 2012 at age 89. This NPR segment includes a brief sample of Thurman’s radio delivery (starting at 3:50).



Figure 3. June Bacon-Bercey on the air in Buffalo during the early 1970s. Image credit: Courtesy June Bacon-Bercey.

June Bacon-Bercey
Although she had a meteorology degree, June Bacon-Bercey decided to start her TV career as a news reporter. As she once told me: “I did not want to do weather on television, only because at that time I felt it was still gimmickry from women.” But in 1971, when the regular weathercaster at Buffalo’s WGR became suddenly indisposed (having allegedly robbed a bank), Bacon-Bercey went on the air and became an immediate hit. In 1972, she was the first woman and the first African-American to earn a Seal of Approval from the American Meteorological Society. After four years in TV weather, Bacon-Bercey went on to a fascinating variety of other science-related endeavors, including serving as chief of broadcast services at NOAA and as a consultant for the Atomic Energy Commission. Fun fact: Bacon-Bercey used part of the $180,000 she won on a TV quiz show in 1978 to launch the American Geophysical Society’s June Bacon-Bercey Scholarship in Atmospheric Sciences for Women.



Figure 4. Don Kent with a example of one of the first TV weather graphics packages, circa the early 1980s. Image: WBZ, courtesy Quincy Patriot-Ledger.

Don Kent
It’s hard to imagine a career bridging more of 20th century weathercasting than that of Don Kent, a legend to generation of Bostonians. Kent died in 2010, and I was grateful for having had the chance to interview him in person in September 2009. Kent grew up listening to, and occasionally pestering, radio weathercaster E.B. Rideout in the 1920s--“he knew I was a weather nut”--and he began volunteering at WMEX just out of high school: “I went to the weather bureau at Boston at 11 a.m., got the first map off the press at 11:30, and got up to the radio station for the 12:55 broadcast,” he told me. Among other big events, he warned listeners of the approach of the catastrophic 1938 New England hurricane. After Coast Guard service during World War II and a radio gig at Quincy’s WJDA, Kent began a multi-decade career at WBZ in 1955, doing both radio and TV segments until he retired in 1983. Here’s a tribute to both Kent’s career and his devotion to children with disabilities at New Hampshire’s Crotched Mountain School.



Figure 5. Marcia Yockey’s reports at WTVW and WFIE (Evansville, IN) were long sponsored by Hesmer’s, a local maker of canned foods. Image credit: Courtesy WFIE.

Marcia Yockey
During her 35 years as a top-rated TV meteorologist in Evansville, Indiana, Marcia Yockey managed to blend a commitment to meteorological rigor with a irrepressible sense of fun that played perfectly in the days when many weathercasters were expected to entertain as well as inform. Yockey came to TV after a decade with the U.S. Weather Bureau, where she landed after World War II interrupted her college chemistry studies (she’d originally intended to become a doctor). She launched her broadcast career at Evansville’s WFIE in 1953, just as the “weathergirl” craze was hitting TV. After that era subsided in the early 1960s, Yockey was one of the very few women who continued as broadcast meteorologists into the 1980s. Yockey’s on-screen antics ran the gamut from delivering weather while in a historic jail cell to windsurfing in the midst of a weather segment. Yet Yockey never sacrificed science for the sake of goofiness. “I used isobars, fronts, and adiabatic lapse rates,” she told me. “I gave [viewers] the map the way it should be.” Yockey died in 2000. You can get a sense of her inimitable style in this tribute montage, along with several other clips on YouTube.


Who else, but the weatherman?
For a taste of midcentury animation at its wackiest, check out the YouTube clip embedded at bottom. It’s a sample reel of forecast segments that were designed in the late 1950s for TV stations that didn’t have their own weathercasters. The idea was that producers would splice the appropriate 20-second clip into the newscast based on the Weather Bureau’s forecast for that day (“overcast and warmer”, “haze with risk of showers,” etc.). The idea never quite caught on--it quickly became apparent that having a live weathercaster was a virtual requirement for any self-respecting newsroom--but these clips live on as a reminder of the wildly experimental nature of TV’s earliest days.



Figure 8. Nick Wiltgen. Image credit: The Weather Channel.

Remembering Nick Wiltgen
The world of weather communication suffered a huge loss last week with the untimely death of Nick Wiltgen, a senior digital meteorologist at The Weather Channel. Nick’s weather.com articles will be familiar to many readers, as I often linked to them from my own posts, and he frequently appeared on Weather Channel segments. Nick joined TWC in 2001 as an on-air radio meteorologist. He shifted in 2012 to the digital arena, where he produced a wide-range of weather- and nature-related content and supervised the team of digital meteorologists at weather.com.

Along with being a superb writer and a engaging colleague, Nick had a phenomenal feel for weather statistics: where to find them, how significant they were, and how fascinating they can be. “Nick was a one-hundred-percent, pure-blood weather geek,” said weather.com’s Jon Erdman. Nick will be missed greatly by colleagues, friends, and family. The Weather Channel has posted these video and text tributes.

Jeff Masters will be back on Monday with more details on this week’s jaw-dropping upgrade of the strength of Category 5 Hurricane Patricia.

Bob Henson








TV Weather Broadcast Meteorology

Absurd January Warmth in Arctic Brings Record-Low Sea Ice Extent

By: Bob Henson , 7:23 PM GMT on February 04, 2016

This winter’s freezing season in the Arctic is falling short. The extent of Arctic sea ice this week is hovering near record-low values for early February, based on observations that extend back to the start of satellite monitoring in 1979. Data from the National Snow and Ice Data Center (NSIDC) shows that last month had the lowest overall Arctic sea ice extent of any January in the satellite record (Figure 1). As detailed in an NSIDC report on Thursday, the total extent of 13.53 million square kilometers (5.2 million square miles) was 1.04 million sq km below the 1981-2010 average and 90,000 sq km below the record from January 2011.



Figure 1. Departures from average in Arctic sea ice extent for January, 1979-2016. Image credit: NSIDC.


Figure 2. Sea ice extent for January 2016 (white), compared to the median January location of the ice edge for the period since 1979 (magenta line). The largest areas of open water where ice is usually present are in the Barents Sea, north of Scandinavia. Image credit: NSIDC.

Only a few weeks are left before the return of polar sunshine puts an end to the freeze-up that typically starts in September and peaks in late February or March. Last year’s maximum extent occurred quite early--on February 25--and it was the lowest in the satellite record, at 14.54 million square kilometers. This year appears to have a reasonable shot at breaking that record.

The not-so-frozen North
Hand in hand with the skimpy ice cover, temperatures across the Arctic have been extraordinarily warm for midwinter. Just before New Year’s, a slug of mild air pushed temperatures above freezing to within 200 miles of the North Pole. That warm pulse quickly dissipated, but it was followed by a series of intense North Atlantic cyclones that sent very mild air poleward, in tandem with a strongly negative Arctic Oscillation during the first three weeks of the month (see Figure 4).


Figure 3. Average air temperatures over the Arctic for January 2016 at the 925-mb level (about 2000 feet above the surface), expressed as departures from the long-term January average in degrees C. Image credit: NOAA Earth System Research Laboratory.


“January was absurdly warm in the Arctic,” said NSIDC director Mark Serreze. According to data from NOAA’s Earth Systems Research Laboratory, the average surface temperature in January between latitude 60°N and the North Pole was -18.2°C (-0.8°F), topping the previous record of -20.6°C (-5.1°F) set in January 2005. Just above the surface (925 mb), the average January temperature of -14.2°C (5.9°F) was well above the previous record of -16.5°C (0.7°F), also set in 2005. The fact that average readings at this level are warmer than at the surface reflects the strong inversion typical of the lower Arctic atmosphere, especially in winter, as cold air hugs the surface and milder air flows just above it.


Figure 4. This cross section through the polar vortex (between latitudes 65°N and 90°N) shows how the height of pressure surfaces (shown in millibars/hPa on the left-hand axis) varied over time from October 2015 to early February 2016. Red values show where a given pressure surface was unusually high in the atmosphere, corresponding to warmer-than-average temperatures. The temperatures have been normalized so that the right-hand legend shows standard deviations from the mean. Image credit: NOAA Climate Prediction Center.

Anyone for bathing in the Barents?
Some of the most visible ice-extent deficits right now are in the Barents Sea, north of Scandinavia. Warm waters carried by the Atlantic Meridional Overturning Current (AMOC) can push all the way northeast into the Barents, making it one of the most variable of the seas that fringe the Arctic. Data from Crysophere Today (University of Illinois at Urbana-Champaign) show that sea ice now covers less than half the area across the Barents that it did a year ago at this time. The difference in area--roughly 350,000 square kilometers--is bigger than the state of New Mexico. (Note that sea ice area is a somewhat different index than sea ice extent, as explained by NSIDC.)

Near the northwest corner of the Barents Sea, temperatures in Svalbard, Norway--at 78°N, the northernmost civilian community on Earth--have been far above average for the entire last month. From January 5 to February 3, the average in Svalbard was -4.7°C (23.5°F), which is a full 19°F above the norm--remarkable for a 30-day period. The coldest reading of the whole period, -11.9°C, was still above the average January high of -13.0°C! Temperatures pushed above freezing on four days, reaching 4.5°C on January 24 (still not a monthly record, though). The WU forecast shows Svalbard remaining unusually mild for at least the next week, with lows at or above the average highs.


Figure 5. The area covered by sea ice in the Barents Sea as of February 4 was around 250,000 square kilometers (right side of black trace), less than half of the value a year ago (left side of black trace). The red trace shows departures from average for the time of year. Image credit: Cryosphere Today/University of Illinois at Urbana-Champaign.

The outlook for 2016
Most of the attention around Arctic sea ice has focused on the dramatic losses in summertime, especially over the past decade. The minimum yearly extent set new record lows in 2007 and again in 2012. Both of these minimums were followed by a year or two of quasi-recovery, but then the long-term trend toward lower summer minimums resumed.

Could 2016 set another new record minimum? It’s far too soon to make any confident predictions. A record-low maximum could give the ice a head start on 2016 melting, but the ultimate outcome will depend mainly on weather patterns still to come, especially in early summer. Warm southerly winds and clear, sunny skies during June and July can make a huge difference in paving the way for a record minimum in September.


Figure 6. The years 2012 (green dashed line) and 2015 (blue line) show how the state of sea ice in late winter and spring doesn’t necessarily correspond to its minimum in September. Sea ice extent in March 2012 was near its long-term average in April, yet it was at a record low in September. Late winter ice was much less extensive in 2015, but that year’s minimum was still considerably higher than in 2012. The extent for 2016 is shown in the red line at far left. Image credit: NSIDC.


Those on the front lines of experimental sea ice prediction stress the role of weather conditions in modulating how any one season will fare. In a 2015 review paper for EOS, Julienne Stroeve (NSDIC) and colleagues from the Sea Ice Prediction Network took a look at what recent efforts have accomplished and what may be possible down the line. Since 2008, the network has issued monthly compilations of sea ice forecasts (available online) updated through the summer, created by more than a dozen participants using a variety of methods. The average of these predictions tends to do somewhat better than any one approach, but even that skill is still limited, especially more than a month or two in advance of the September minimum.

“Because the atmosphere is mostly unpredictable beyond 1 or 2 weeks, the sea ice forecasts initialized in late spring may not be able to accurately predict sea ice features that develop as a result of extreme summer atmospheric conditions,” said the EOS paper.

Idealized experiments suggest that the state of Arctic sea ice might be predictable with some skill as far as two years in advance. To reach this theoretical goal, we would need major advances in both Arctic observations and modeling. There’s another catch: climate change itself may make the task harder. “Interannual variability of summer sea ice extent will likely increase in coming decades,” noted Stroeve and colleagues, “and some scientists suggest that this might lead to a reduction in predictability.”

We’ll be back with a new post on Friday.

Bob Henson

Arctic Climate Change

Groundhog Says: Early Spring! Plus: a Groundhog Day Tornado Outbreak?

By: Jeff Masters and Bob Henson , 5:02 PM GMT on February 02, 2016

In Punxsutawney, Pennsylvania, home of the world's most famous prognosticating rodent, Punxsutawney Phil, gloomy clouds prevailed at sunrise on Tuesday morning, preventing Punxsutawney Phil from seeing his shadow. His fearless prognostication for the remainder of winter, as presented as his official groundhog.org web site, looks like this, then:

“Hear Ye, Hear Ye, Hear Ye
Now, this Second Day of February, Two Thousand and Sixteen, the One Hundred and Thirtieth Annual Trek of the Punxsutawney Groundhog Club….
Punxsutawney Phil, the Seer of Seers, Prognosticator of All Prognosticators, was awakened from his borrow to the cheers of his thousands of faithful followers….
In Groundhogese, he directed the President and the Inner Circle to the precise prediction Scroll, which translated reads:



The inner circle goes to great ends
 
To keep me abreast of latest trends

Down in my burrow I never get bored
   
Riding on my hover board

And I sure have fun flying my drone
 
But weather forecasting is my comfort zone

Is this current warm weather more than a trend?
   
Per chance this winter has come to an end?

There is no shadow to be cast,
   
An early Spring is my forecast!"



Figure 1. Canada's famous albino groundhog named Wiarton Willy from the town of Wiarton, Ontario. Willie saw his shadow at dawn Tuesday, so his prediction calls for six more weeks of winter. However, Nova Scotia’s Shubenacadie Sam didn’t see his shadow this morning from his little shed at a provincial wildlife park northeast of Halifax, and in New York City, groundhog forecaster Staten Island Chuck also failed to see his shadow, and predicted an early end to winter. Image credit: wunderphotographer pincollector1.

Grading Phil's forecasts
Phil saw his shadow in 2015, predicting six more weeks of winter. While February ended up colder than average over the contiguous U.S. in 2015, March was much warmer than average (the 12th warmest March since 1895), making it difficult to grade Phil's forecast as being successful or a flop. NOAA’s National Centers for Environmental Information (NCEI) analyzed Punxsutawney Phil’s forecasts between 1988 - 2015 (thanks to Doyle Rice of USA Today for pointing this out.) If we evaluate just the twelve years when the departure of February and March temperatures from average over the contiguous U.S. were both of the same sign, Phil had five correct forecasts and seven blown forecasts. NOAA concluded in last year's version of this analysis that “It really isn't a 'bright' idea to take a measure such as a groundhog's shadow and use it as a predictive meteorological tool for the entire United States.”

How did this this crazy tradition start?
It all started in Europe, centuries ago, when February 2 was a holiday called Candlemas (much like Halloween and May Day, Candlemas is another ancient holiday positioned near the halfway point between solstice and equinox.) On Candlemas, people prayed for mild weather for the remainder of winter. The superstition arose that if a hibernating badger woke up and saw its shadow on Candlemas, there would be six more weeks of severe winter weather. When Europeans settled the New World, they didn't find any badgers. So, instead of building wooden badgers, they decided to use native groundhogs (aka the woodchuck, land beaver, or whistlepig) as their prognosticating rodent.

The Groundhog Oscillation: convincing evidence of climate change!
According to a 2001 article published in the prestigious Annals of Improbable Research, "The Groundhog Oscillation: Evidence of Global Change", Punxsutawney Phil's forecasts have shown a high variability since 1980. This pattern, part of the larger "Groundhog Oscillation" or GO cycle, is convincing evidence of human-caused climate change.


Figure 2. Temperature outlook for February 2016, as predicted by NOAA's Climate Prediction Center (CPC) on January 31, 2016. A continuation of the warm in the north and west, and cool in the south pattern is favored.

What the pros say
The latest 10-day runs of the GFS model and the European model show an outbreak of Arctic air pushing through the Midwest beginning on Monday next week, and bringing much below-average temperatures to large portion of the eastern half of the country during the second week of February. As discussed by Bob Henson in his Monday blog post, this plunge of cold is expected to happen as a consequence of a split of the polar vortex caused by a Sudden Stratospheric Warming (SSW) event. However, NOAA’s experimental 3-4 week temperature forecast for Feb. 13-26 shows no strong indication for either above- or below-normal temperatures east of the Great Plains, so next week's cold blast may be just a one-week affair. The latest seasonal forecast from The Weather Company's Business Solutions group (formerly known as WSI.com) agrees with this idea. Heading into March and April, they predict a classic El Niño pattern of relative warmth across the northern states and cooler than average temperatures across the southern tier of states, with March being more consistently colder than average than February. The latest 3-month forecast for February - April from Columbia University's International Research Institute for Climate and Society and from NOAA's Climate Prediction Center (CPC) show a similar pattern of warmth in the north and coolness in the south. Wunderblogger Steve Gregory has a more detailed analysis of the long-range forecast for February in his Monday afternoon post, Major Snow storm - Severe T-Storms and Pattern Change.


Figure 3. Outlook for severe weather on Tuesday, issued at 10:29 am EST Tuesday, February 2, 2016, by the NOAA Storm Prediction Center.

Not in the groundhog's forecast: Tornado outbreak possible Tuesday PM
A springlike severe weather setup is taking shape for Tuesday afternoon between the Mississippi River and the Appalachians. Gulf moisture is already in place, with dew point temperatures already into the 60s as far north as western Tennessee. Mild, unstable air will continue flowing from the Gulf behind a warm front now lifting northward through Kentucky, while a sharp cold front and upper-level energy approach from the west. NOAA's Storm Prediction Center is calling for an enhanced risk of severe weather from Mississippi and Alabama into western Tennessee and Kentucky. As of late Tuesday morning, the areas at greatest threat for discrete supercell storms later Tuesday---perhaps even strong tornadoes--are near the warm/cold front intersection zone, over western TN and KY, and across central and southern MS and AL, especially later in the evening. A weaker round of severe weather is possible Wednesday east of the Appalachians, from the Gulf Coast to the Delmarva.

Jeff Masters and Bob Henson


Video 1. Smart groundhogs use WU to improve their prognostications!

Winter Weather Severe Weather

Blizzard Sweeping into Central States; A Cold February in Store?

By: Bob Henson , 6:05 PM GMT on February 01, 2016

In the state of Iowa, Monday night looks to be a wild one both politically and meteorologically. The first-in-the-nation 2016 presidential caucuses are scheduled to begin at 7:00 pm CST, just as a powerful winter storm begins to roll into the state. Blizzard warnings are out from eastern Nebraska into northwest Iowa from very early Tuesday morning into Wednesday. The onslaught is part of a sprawling, energetic winter storm that crashed ashore in Southern California on Sunday. High winds blew across the Los Angeles and San Diego areas for an unusually long period from Sunday afternoon into Monday morning, including a gust to 62 mph around 2 am PST Monday at Mission Beach. “It’s very rare to get winds of this speed at our sea-level coastal sites,” said Brandt Maxwell, an NWS forecaster in San Diego.

The storm also brought much-needed moisture to Southern California. Santa Barbara picked up just over 1” of rain, with scattered amounts closer to 0.5” across the L.A. and San Diego coastal areas. Some higher elevations got as much as 4” of liquid over the weekend, with snow levels dipping below 2500 feet in the mountains of Ventura and Los Angeles counties. Further north, heavy snows plastered much of the Sierra Nevada. Much more moisture is needed across the region to make a significant dent in the long-term drought, as we discussed on Friday.


Figure 1. With the downtown Los Angeles skyline in the background, a large tree toppled by strong winds on Sunday afternoon, Jan. 31, 2016, barely missed several parked cars on Temple Street. In the San Diego area, a motorist was fatally struck by a tree that was knocked down by powerful winds. A winter storm brought downpours, wind and snow across California over the weekend, as strong winds downed dozens of trees and power poles and ripped off rooftops across Southern California. Image credit: Ian Feiner, via AP.

A mixed bag this week: Snow, wind, storms, and record warmth
Thundersnow was reported in the higher terrain of central and northern Arizona on Sunday night as the upper-level storm gradually organized while sweeping east. Near Flagstaff, meteorologist David Blanchard heard several rounds of thunder over a two-hour period, with “brilliant nearby flashes” around 10:15 pm MST. “In my 15 years in northern Arizona, this is probably the most thunder and lightning I've experienced in a snow event,” Blanchard said. A wind gust to 68 mph was observed at a WU station just north of Tucson as the stormy front passed by around 1 am PST (thanks to Mark Albright, University of Washington, for this tidbit).

Denver and Boulder could see more than a foot of snow on Monday into early Tuesday. That storm will produce a swath of snow accompanied by high winds as it spreads across southern Nebraska, northwest Kansas, northwest Iowa, and central Wisconsin into Tuesday. Ahead of the storm, a few record highs are possible over the Northeast early this week as mild air sweeps northward from the Gulf of Mexico.

NOAA’s Storm Prediction Center is calling for an enhanced risk of severe weather on Tuesday from northern Mississippi into western Kentucky. The modest level of instability is more likely to support damaging downburst winds rather than a major tornado outbreak.

January temps firmly in El Niño mold--but what about February?
Once again, temperatures across the nation in January behaved much as one would expect during a strong El Niño. WU member Eric Webb (North Carolina State University) has been tracking U.S. temperatures over the last few months, comparing them to the departures from average that were observed during the strongest El Niño events since 1900. Figure 2 shows the correspondence. Readings from October to December trended warmer in most places than in past strong El Niños, consistent with the overall warmth of our 21st-century climate. At the same time, the the indications of which parts of the country would be warmest during each month verified quite well. The same is true for January, although in this case much of the nation was actually cooler than it was during past El Niños.


Figure 2. Top row: month-to-month variations in average temperature during strong and “super” El Niño events between 1895 and 2014. Bottom row: variations that were actually observed from October 2015 (left) through January 2016 (right). Temperature departures are shown in blue/green colors (cooler than average) and red/orange colors (warmer than average), as calculated against the long-term average for the period 1895-2000. The El Niño events in these composites (peak Niño3.4 indices of at least 1.5°C above average for at least three overlapping three-month periods) include 1896-97, 1902-03, 1930-31, 1940-41, 1957-58, 1965-66, 1972-73, 1982-83, 1987-88, 1991-92, and 1997-98. Image credit: Eric Webb, @webberweather, using a mapping/analysis tool from NOAA’s Earth System Research Laboratory.


Colder-than-average winters have been a recurrent feature over large parts of the northern midlatitudes over the last few years, despite the overall rise in global temperature. As February unfolds, we may see a lively tug-of-war between El Niño’s tendency for mildness over the northern U.S. and Canada and the potential for marked cold over most of central and eastern North America. We can expect the latter part of this week to be seasonably chilly over large parts of the U.S. in the wake of the week’s winter storm. The big question then becomes whether a rapid warming of the Arctic stratosphere (see Figure 3) will contort the polar vortex in a way that favors bitter cold over eastern North America. The GFS and ECMWF models suggest that the jet stream across North America is likely to become highly meridional (north to south) by next week, racing from the deep Arctic to the Deep South. If this comes to pass, it could push one or more bona-fide rounds of Arctic high pressure and severe cold from central and eastern Canada into the U.S. Midwest and Northeast and perhaps into the South. As for the latter half of February, NOAA’s experimental 3-4 week temperature forecast for Feb. 13-26 shows no strong indication for either above- or below-normal temperatures east of the Great Plains.



Figure 3. Temperatures above the North Pole (90°N) in the middle of the stratosphere, at the height of 10 mb (roughly 100,000 feet). Readings for winter 2015-16 are shown in purple (observed) and orange (predicted as of January 31, 2016), in Kelvins (degrees Celsius + 273.15]. After dipping to near-record values for the satellite era in late January, temperatures are expected to soar to near-record highs by early February, a potential leap of more than 60°C (100°F)! Quickly rising temperatures at this altitude are one indication of the phenomenon known as a sudden stratosopheric warming. SSWs can cause high-altitude winds in the polar vortex to slow or reverse direction. This would make it more likely that the vortex will become distorted or split, which in turn would raise the odds of midlatitude cold intrusions. Image credit: Paul Newman (NASA), Eric Nash (SSAI), and Steven Pawson (NASA), courtesy Judah Cohen (AER).


It’s official: WU is now part of IBM
The purchase of The Weather Company (TWC) by IBM, announced in October, was finalized on Friday, January 29. This acquisition includes Weather Underground as well as WSI (TWC’s global business-to-business brand), weather.com, and The Weather Company brand. It does not include The Weather Channel's TV network, which will license weather forecast data and analytics from IBM under a long-term contract. (The Weather Underground series continues to air on TWC.)

Henceforth, WSI will be known as “The Weather Company, an IBM Business,” with Weather Underground remaining as a unit within The Weather Company. IBM’s Watson cloud platform will incorporate TWC technology to expand its Internet of Things (IoT) services for business and consumers. The Weather Company plans to collaborate with IBM’s weather research team on next-generation weather models and to work with the IBM Watson team on sophisticated analytics. “Since I became president of WSI in 1991, we’ve been through many changes,” said Mark Gildersleeve. “This promises by far to be the most significant, in particular because IBM will enable us to deliver mission-critical solutions on a much larger scale.”

IBM also announced that weather.com will be expanding to China, India, Brazil, Mexico, and Japan. For more details on the acquisition, see the Weather Company news release.

At Weather Underground, we’re looking forward to what these new collaborations will enable us to accomplish in the way of innovative weather products and technology. Meanwhile, Jeff Masters and I will keep our WunderBlog rolling. As always, we value your contributions as members of our unique WU community. Thanks for being here!

Bob Henson

Winter Weather Blizzard Extreme Weather


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