US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
348 PM EST Tue Dec 22 2020
 
Valid Friday December 25 2020 - Tuesday December 29 2020
 
Hazards:
- Heavy precipitation across portions of the Pacific Northwest, Fri-Sun, Dec 25-Dec 27.
- Heavy precipitation across portions of the Central Great Basin, California, and the Southwest, 
Mon-Tue, Dec 28-Dec 29.
- Heavy precipitation across portions of the Northeast, Fri, Dec 25.
- Heavy rain across portions of California, Sun-Mon, Dec 27-Dec 28.
- Heavy snow across portions of the Northeast, Mon, Dec 28.
- Flooding possible across portions of the Great Lakes, the Mid-Atlantic, the Northeast, the 
Central Appalachians, and the Ohio Valley.
 
Detailed Summary:

Parts of the Northeast and West will experience hazardous weather during the medium range period 
(Friday, December 25th-Tuesday, December 29th). An upper-level low will tilt negatively as it moves 
into the eastern seaboard on Friday (Christmas day). Heavy rain and snow that impacted the east 
coast on Christmas eve will recede into southern and eastern Maine on Christmas day, where there is 
an area of heavy precipitation. Flooding remains a concern in the Northeast as recent heavy 
snowfall melts due to above average temperatures out ahead of this system on Thursday and Friday. 
Meanwhile, in the west, another deep upper-level disturbance will generate heavy snowfall over the 
Olympic mountains and rainfall for the surrounding lower elevations. This disturbance will weaken 
to a mere shortwave as it crosses the lower 48 over the weekend before restrengthening and 
developing a potent area of surface low pressure. This low pressure system may go on to produce 
heavy snowfall over interior portions of the Northeast on Monday, particularly over the 
Adirondacks, but current guidance may trend a bit farther south with the highest precipitation 
amounts. Another low pressure system will enter the West coast on Monday, bringing with it the 
chance for heavy snowfall to the Sierra and rain for the surrounding low elevations.

Mainland and the Panhandle of Alaska will remain relatively quiet throughout the medium range 
period, while the Aleutians may experience some high winds as a very deep area of low pressure 
moves itself into the Bering Sea.

Kebede