1:40 PM | **Record warmth to continue for another day in the eastern US…big changes coming in March**
Paul Dorian
The nation is divided currently with very cold air relative-to-normal situated across the western states and record-warmth in much of the eastern US. The noontime map on the left shows many locations with near record or record warmth in the eastern US and several with near record or record cold in the western US (more numerous a few hours ago). The map on the right shows the extremes relative-to-normal from the west to the east. Maps courtesy coolwx.com (left) and "weather.us", Dr. Ryan Maue, (right).
Overview
Today has seen many temperature records go down across the nation with record warmth in the eastern US and record cold in the interior west. In the local area, record highs have already been set at Dulles Airport (IAD) at 71 degrees (1971) and others could fall in the next couple of hours and Wednesday promises to result in numerous record high readings across the Mid-Atlantic. It’ll turn much cooler on Thursday in the Mid-Atlantic region and there will be multiple shots at rain during the late week and weekend; especially, to the north of the PA/MD border. Longer term, signs continue to point to big changes arriving in early March which should lead to more colder-than-normal conditions in the Mid-Atlantic region and perhaps even more opportunities for accumulating snow.
12Z GEFS forecast maps of 850 mb temperature anomalies averaged over 5 day periods with days 2-6 on left (warmer-than-normal in the eastern US) and days 12-16 on right (colder-than-normal across much of the nation); maps courtesy NOAA/EMC, tropicaltidbits.com
Near-term record warmth in the eastern US
While the western US has seen a dramatic chill down (even reports of snow near Los Angeles), temperatures are soaring today across the Ohio Valley and in the Mid-Atlantic region given the increasing amounts of sunshine that have developed following early morning clouds and fog. At 1PM, Philly Airport has officially jumped to 63 degrees and Reagan Airport (DCA) in Washington, DC has already climbed to 71 degrees and these should jump over the next few hours given current mainly sunny skies. Temperatures will stay at very mild levels in the overnight hours and likely climb to record highs in many spots on Wednesday afternoon with the 70’s virtually a guarantee in a large part of the Mid-Atlantic.
A cold front will push through tomorrow night and bring us back to some reality by Thursday with temperatures some twenty degrees lower than tomorrow, but still not unreasonably cold for this time of year. With the cool down will come multiple chances for rain during the late week and weekend; especially, to the north of the Mason-Dixon Line where wave-after-wave will likely impact the region.
12Z GEFS forecast maps of 500 mb height anomalies for today, February 20th (left) and March 2nd (right). By early March, strong high-latitude blocking will develop over Greenland and a trough of low pressure will begin to retrograde (i.e., move from east-to-west) to a position near the US east coast; courtesy NOAA/EMC, tropicaltidbits.com
March chill down
The overall weather pattern across North America looks like it will change significantly by early March. To begin with, strong blocking in the upper part of the atmosphere will take hold in the northern latitudes (e.g., Greenland) and this will result in a better chance for cold air masses to drop into the eastern US as the month of March gets underway. In addition, a trough of low pressure at 500 mb will actually retrograde (i.e., move from east-to-west) into the eastern US from the western Atlantic Ocean as we begin March and simultaneously, a ridge will begin to back-up from the Central Plains to a position over the Rockies and another trough will begin to move westward from the west coast to the eastern Pacific Ocean. This potential weather pattern across North America in early March may not only result in colder-than-normal air returning to the eastern US, but it also allows for the possibility of a strong coastal storm – something we’ll have to monitor closely as March gets underway.
Meteorologist Paul Dorian
Vencore, Inc.
vencoreweather.com