US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
339 PM EST Wed Feb 03 2021
 
Valid Saturday February 06 2021 - Wednesday February 10 2021
 
Hazards:
- Heavy snow across portions of the Great Lakes and the Upper Mississippi Valley, Sat-Mon, Feb 
6-Feb 8.
- Heavy snow across portions of the Northeast and the Great Lakes, Sun-Mon, Feb 7-Feb 8.
- Flooding likely across portions of the Mid-Atlantic.
- Much below normal temperatures across portions of the Central Plains, the Lower Mississippi 
Valley, the Central Appalachians, the Tennessee Valley, the Great Lakes, the Middle Mississippi 
Valley, the Mid-Atlantic, the Southern Appalachians, the Southern Plains, and the Ohio Valley, 
Sun-Wed, Feb 7-Feb 10.
- Much below normal temperatures across portions of the Lower Mississippi Valley and the Southern 
Plains, Tue-Wed, Feb 9-Feb 10.
- Much below normal temperatures across portions of the Central Plains, the Northern Plains, the 
Northern Rockies, the Middle Mississippi Valley, the Upper Mississippi Valley, and the Great Lakes, 
Sat-Wed, Feb 6-Feb 10.
- Much below normal temperatures across portions of the Great Lakes, the Mid-Atlantic, the 
Northeast, the Central Appalachians, and the Ohio Valley, Mon-Tue, Feb 8-Feb 9.
- Much below normal temperatures across portions of mainland Alaska, Mon-Wed, Feb 8-Feb 10.
- Much below normal temperatures across portions of mainland Alaska, Sat-Wed, Feb 6-Feb 10.
 
Detailed Summary:

The medium range Hazards period (Saturday, February 6th to Wednesday, February 10th) is 
characterized by widespread frigid temperatures and winter weather across the Central U.S. At the 
beginning of the forecast period Saturday morning, guidance is in good agreement regarding 
placement of pronounced ridging over the Eastern Pacific into Alaska, and a broad longwave trough 
north of the Great Lakes. The cyclonic northwesterly flow sets the stage for the first major 
intrusion of cold Arctic air into the U.S. this season, with brutally cold temperatures 25 degrees 
below normal funneling in behind a pair of sweeping cold fronts February 6th-10th. Strong cold 
advection behind an occluding frontal system in the Northern Tier sets the stage for lake effect 
snow the 6th-8th, as anomalously cold temperatures move atop the largely unfrozen Great Lakes.

While locations downwind the Great Lakes are a good bet for localized heavy snow, the situation in 
the Northeast appears far less certain. Earlier ensemble guidance highlighted the possibility of a 
coastal low tracking along/near the Mid-Atlantic and Northeast coastline, with associated snowfall 
impacting the Northeast. However, there remains considerable disagreement regarding the timing and 
track of this system. Given the trend in the ensemble guidance to push the low more out to sea, 
have removed the Heavy Snow area over the region.

Elsewhere, precipitation looks to be generally light. Some modest rainfall amounts are possible in 
the Southeast/Florida over the weekend along a frontal boundary, and the back edge of the 
precipitation could fall as snow or mix in the Southern Appalachians. Then for the first half of 
the workweek, there is some chance for precipitation along the base of the Arctic high pushing into 
the central U.S. The precipitation could be in the form of impactful snow or ice given the cold 
temperatures in place, but at this point, there is low confidence regarding the placement and 
amounts of this potential precipitation. Areas from the Central/Southern Plains toward the Middle 
Mississippi and Ohio Valleys should continue to monitor the latest forecasts for this possible 
threat.

Over Alaska, model and ensemble agreement is increasing that an anomalously deep upper-level low 
will lead to much below average temperatures starting over the weekend for the eastern part of the 
mainland and spread westward by the first half of the workweek. Bitterly cold temperatures are 
forecast to reach into the -40s for parts of the North Slope and the Yukon Flats of eastern Alaska, 
while below average temperatures by 20-30 degrees are likely for much of the mainland. Relatively 
weak low pressure systems over the Gulf of Alaska could lead to snow across coastal portions of the 
south-central mainland and eastward into the Panhandle for Monday-Wednesday, but model 
disagreements remain in terms of precipitation amounts, and at this point look to remain below 
hazards thresholds.


Asherman/Tate