Monday, February 1, 2016

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

By: Bob Henson , 6:05PM,GMT on February 1,2016



 
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

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