All-Time Warmth for February Stretches to New England
A February remarkable for its long stretches of mildness steamed onward Thursday, with more all-time records for the month continuing to tumble across wide stretches of the U.S. The apex of the record-setting warmth expanded on Thursday from the Midwest (which we covered in our last post) into New York and New England (see below). A staggering number of daily record highs have been set in recent days, especially when juxtaposed against the sparse number of record lows this month. As of Friday morning, NOAA’s U.S. Records site had compiled 4492 daily record highs for February 2017, against a mere 29 daily record lows, for a lopsided highs-to-lows ratio of 155-to-1. With record highs expected to far outpace record lows through the end of the month, February has a very good chance of smashing the highest ratio in modern records: 44-to-1, from November 2016, as reported by longtime records tracker Guy Walton (@climateguyw) in his new Guy on Climate blog. Brian Kahn (Climate Central) puts it this way: “The U.S. is poised to set a record-setting record.”
Another astounding tidbit: the NOAA site shows 248 monthly record highs for February, but no monthly record lows at all. This is the first time that Walton recalls seeing such a skewed ratio of monthly records. It almost goes without saying that this onslaught of February records is entirely consistent with the warming of national and global climate being generated by human-produced greenhouse gases, as noted by Andrew Freedman (Mashable).
Mild air flowing into U.S. from atop record-warm northwest Atlantic waters
The polar jet stream and associated surface front that typically swings through the United States in late winter has been hovering close to the U.S./Canada border, with intrusions of seasonally cold air into the central and eastern United States either absent or short-lived over the last few days. The air mass south of this boundary has been notably mild and humid, flowing northward after spending time atop sea-surface temperatures that are at record-warm levels for late February.
“Western Atlantic basin SSTs are on fire!” tweeted hurricane forecaster Eric Blake (@EricBlake12) on Thursday. “Easily warmest on record--especially the Gulf of Mexico.” This warmth is especially well reflected in a swarm of daily record highs and record-warm lows at Galveston, TX, where records began in 1874. Since September 1, Galveston has set an impressive 33 heat records of various types--more than any other Southeast city during that period in a compilation pulled together late Thursday by Houston meteorologist Matt Lanza (@MattLanza). Eric Berger (Space City Weather) has more on the extremely mild Houston/Galveston winter.
Figure 1. Sea-surface temperatures early on Thursday, February 23, 2017, were running 1-2°C (1.8-3.6°F) above average over large parts of the Gulf of Mexico, Caribbean, and northwest Atlantic. Image credit: www.tropicaltidbits.com, via Eric Blake.
Figure 2. An enhanced risk of severe weather is predicted by NOAA’s Storm Prediction Center for Friday, February 24, 2017 from Detroit, MI, to Cincinnati, OH, including parts of four states. Image credit: WU, via NOAA/SPC.
Severe storms possible in eastern Great Lakes on Friday
With a potent upper-level trough approaching the relentlessly warm, moist air mass over the eastern Great Lakes, an outbreak of severe weather may erupt on Friday. At 6:30 am CST, NOAA’s Storm Prediction Center placed an “enhanced risk” area from southern Michigan across eastern Indiana and western Ohio into north central Kentucky. Severe weather outbreaks in winter typically feature very strong wind shear (winds increasing and/or turning with height), along with just enough instability to get thunderstorms forming. There’s ample instability in this case, given the very mild, moist surface air in place, but the wind shear is fairly linear, with little directional change with height. As a result, the odds are tilted away from rotating supercell storms (the kind most likely to produce violent tornadoes) and instead toward lines or clusters of severe storms, eventually forming a longer squall line. The biggest threat of the day appears to be locally damaging winds, although tornadoes and marginally severe hail (0.75” or larger in diameter) can’t be ruled out. The odds of widespread severe weather will be lower on Saturday as the system moves across the Northeast and New England, but strong winds may still mix to the surface where thunderstorms do occur.
The best odds for a supercell on Friday is close to a surface low that will be traversing southern Michigan--a state where any severe weather in February is rare. Since 1986, the NWS office in Detroit has issued tornado or severe thunderstorm warnings for just two severe weather events, the most recent being in 1999. According to the Tornado History Project, since 1950, only one tornado has ever touched down in February in Michigan: an F2 twister that hit southeast Michigan on February 28, 1974. Ohio has recorded 17 February tornadoes since 1950, and Indiana has had 31.
Texas and the century mark: 100°F heat on Thursday
We expect to see temperatures over 100°F in Texas in July, but not in February! Temperatures soared past the 100 degree mark at several stations in southern Texas on Thursday, flirting with the all-time U.S. temperature record for February. According to wunderground weather historian Christopher C. Burt, the Texas (and national) February heat record is either a questionable 104° at Fort Ringgold (now known as Rio Grande City) on Feb. 20, 1902 or, more likely, 103° at La Joya on Feb. 28, 2009 and also at Laredo on Feb. 20, 1986 and Feb. 27, 2011. The 101°F reading in McAllen, Texas on Thursday was their hottest February temperature ever recorded. A number of COOP and Mesonet stations also exceeded 100°F on Thursday, with the hottest being a 107°F mark at Falcon Lake on the Mexican border. However, we asked south Texas weather expert Richard "Heatwave" Berler (@Heatwave KGNS) about this mark, and he responded: "I think that the thermometer is miscalibrated or exposed. It consistently runs higher than nearby thermometers during the daytime." Another site at Falcon Lake recorded 103°F (originally reported as 105°) though, and this may be a reasonable measurement, since there were three Mexican stations near Falcon Lake that reported 103°F - 104°F at that time. Update: The NWS/Brownsville office reported in a tweet Friday afternoon that the Falcon Lake COOP station recorded 103°F on Thursday. This ties the most reliable candidates for the national February record noted above.
Here are the 100°F readings in Texas from from February 23 as recorded in the NOAA Weather and Hazards Viewer (thanks go to Hal Needham for alerting us to this tool):
107°F at Falcon Lake RAWS
105°F at Falcon Lake COOP (APRSWXNET/CWOP)
102°F in Atlee
102°F in Dilley
101°F at Zapata
100°F at Faith Ranch Airport
100°F at Cotulla
100°F - 101°F at three stations in McAllen
101°F at Laredo
The hot temperatures in southern Texas have increased wildfire risk this week, and a Red Flag Warning for dangerous fire conditions was posted on Friday for most of the region.
Figure 3. As piles of snow melt in the foreground, Williams College students take advantage of the unseasonably warm weather by dressing in shorts and tank tops as they hang out and study outside Chapin Hall on the school's campus in Williamstown, Massachusetts, on Thursday, February 22, 2017. The campus lies just a few miles south of Bennington, Vermont, where a new state record high for February was set on Thursday. Image credit: Gillian Jones /The Berkshire Eagle via AP.
Monthly records melt in Hudson and Champlain valleys
At least two states have seen all-time statewide highs for February this week. Vermont had its warmest February temperature on record Thursday, February 23, with Bennington soaring to 69°F. According to WU weather historian Christopher Burt, the previous state record for February was 68°F, set in Bennington in February 1957. It’s possible other sites in Vermont also reached or topped 69°F on Thursday. In Wisconsin, Janesville and Boscobel both hit 72°F on Wednesday, February 22. According to Burt, it appears that the previous state record was 69°F at multiple locations. Amazingly, he adds, at least 12 other official reporting sites in Wisconsin tied or broke that previous state record on Wednesday!
All-time records for February set on Thursday, February 22, included:
Albany, NY: 69°F (previous record 68°F on Feb. 22, 1997; records began in 1874)
Glens Falls, NY: 68°F (previous record 65°F on Feb. 21, 1981; records began in 1944)
Burlington, VT: 63°F (previous record 61°F on Feb. 22, 1981; records began in 1883)
Montpelier, VT: 63°F (previous record 61°F on Feb. 19, 1981, and Feb. 22, 1997; records began in 1948)
St. Johnsbury, VT: 62°F (tied) (previous record 62°F on Feb. 21, 1981; records began in 1984)
Some of these brand-new all-time monthly records in northern may be in jeopardy on Friday and/or Saturday, as yet another surge of very mild air pushes into New England ahead of the severe-weather-producing storm now over the Great Lakes. We can also expect a continuing avalanche of daily record highs throughout much of the eastern U.S. (see images below). Update: Boston reached 71°F at around 12:30 pm EST Friday, breaking the city’s all-time February record of 70°F from Feb. 24, 1985. Records in Boston go back to 1872.
Flood threat from snowmelt ramping up across New York and New England
Flood watches are in effect this weekend from the Adirondacks of New York to parts of eastern Maine. Although an inch or more of rain could fall this weekend, the bigger reason for the flood watches is the persistent warmth that’s been kicking snowmelt season into early overdrive. The equivalent of 3” - 4” of rainfall could be produced by snowmelt alone over the Adirondacks and eastern Vermont, according to the National Weather Service in Burlington, with the potential for significant rain atop the snowmelt. “That’s a lot of liquid for our rivers to handle. And the ground is also frozen, so not much will soak in,” noted the office in a morning forecast discussion. In general, flooding is expected to be mild to occasionally moderate, but more significant floods could occur over the weekend if and where ice jams complicate the picture.
Have a great weekend, everyone!
Bob Henson and Jeff Masters
Figure 4. High temperatures across the northeastern U.S. on Thursday, February 23, 2017. Image credit: NWS Eastern Region.
Figure 5. Record daily highs set or tied across the northeastern U.S. on Thursday, February 23, 2017. Image credit: NWS Eastern Region.
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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather