US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
343 PM EST Thu Feb 04 2021
 
Valid Sunday February 07 2021 - Thursday February 11 2021
 
Hazards:
- Heavy snow across portions of the Middle Mississippi Valley, the Great Lakes, and the Ohio 
Valley, Mon, Feb 8.
- Heavy snow across portions of the Great Lakes and the Upper Mississippi Valley, Sun-Thu, Feb 
7-Feb 11.
- Heavy snow across portions of the Northeast and the Great Lakes, Tue-Wed, Feb 9-Feb 10.
- Much below normal temperatures across portions of the Central Plains, the Lower Mississippi 
Valley, the Northern Plains, the Tennessee Valley, the Great Lakes, the Northern Rockies, the 
Middle Mississippi Valley, the Upper Mississippi Valley, the Southern Plains, and the Ohio Valley, 
Sun-Thu, Feb 7-Feb 11.
- Much below normal temperatures across portions of the Lower Mississippi Valley and the Southern 
Plains, Tue-Thu, Feb 9-Feb 11.
- Much below normal temperatures across portions of mainland Alaska, Mon-Thu, Feb 8-Feb 11.
 
Detailed Summary:

The medium range Hazards period (Sunday, February 7th to Thursday, February 11th) is characterized 
by widespread frigid temperatures and winter weather in the Midwest and Northeast U.S. At the 
beginning of the forecast period Sunday morning, guidance is in good agreement on placement of 
pronounced ridging over the Eastern Pacific nosing into Alaska, and a broad longwave trough 
centered north of the Great Lakes slowly meandering eastward. The associated cyclonic northwesterly 
flow ushers in the first major intrusion of Arctic air into the U.S. this season, as brutally cold 
temperatures 25-30 degrees below takes hold in the north-central U.S. before pushing into the 
Southern Plains around midweek. Aside from bitterly cold temperatures, the prolonged cold advection 
regime sets the stage for multiple days of lake effect snow beginning Sunday over the Upper 
Michigan Peninsula, with cold low level flow moving along the fetch of an unfrozen Lake Superior. 
Portions of the Upper Great Lakes/Middle Mississippi Valley are also under the gun for a bout of 
impactful snow February 8th as a warm air glides atop the shallow Arctic airmass ahead of a fast 
moving disturbance.

While portions of the Midwest are a good bet for localized heavy snow, the potential for winter 
weather in the Mid-Atlantic/Northeast late this weekend appears far less certain. The 12Z ECMWF was 
in general agreement with the GFS/GEFS mean regarding the placement of a shortwave trough over the 
Tennessee Valley with a developing coastal low in the Carolinas. However, considerable uncertainty 
remains with respect to the exact track of the low through Monday, with implications for potential 
hazards along the coast. Should the system track further northwest closer to the coast as 
advertised by the 12Z GFS and ECMWF, it appears plausible for the area to see several inches of 
snow on the northwest side of the system. Even if this scenario were to occur, the progressive 
nature of the low pressure will limit significant snowfall accumulations. Another shot of heavy 
snow will make its way into the Northeast Tuesday-Wednesday as a shortwave pivoting around the main 
upper low pushes a frontal system through the region. Areas closer to Lake Erie will double dip 
lake effect and synoptic lift to produce heavy snow in 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. Then for the first half of the 
workweek, there is some chance for precipitation along the base of the Arctic high pushing into the 
Southern 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. 

Over Alaska, model and ensemble agreement is increasing that a deep upper-level low will lead to 
much below average temperatures starting Monday of next week. 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-Thursday, but model disagreements 
remain in terms of precipitation amounts, and at this point look to remain below hazards thresholds.


Asherman/Tate