US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
344 PM EST Fri Dec 25 2020
 
Valid Monday December 28 2020 - Friday January 01 2021
 
Hazards:
- Heavy precipitation across portions of California, Mon-Tue, Dec 28-Dec 29.
- Heavy precipitation across portions of the Central Rockies, Mon, Dec 28.
- Heavy precipitation across portions of the Central Plains, the Middle Mississippi Valley and the 
Great Lakes, Tue-Wed, Dec 29-Dec 30.
- Heavy precipitation across portions of the Southern Appalachians, Wed-Thu, Dec 30-Dec 31.
- Heavy precipitation across portions of the Northeast, Fri, Jan 1.
- Heavy rain across portions of California and the Pacific Northwest, Wed-Thu, Dec 30-Dec 31.
- Heavy rain across portions of the Central/Southern Plains and the Middle/Lower Mississippi 
Valley, Tue, Dec 29.
- Heavy rain across portions of the Middle/Lower Mississippi Valley, the Tennessee/Ohio Valley, the 
Southeast and the Southern Plains, Wed, Dec 30.
- Heavy rain across portions of the Northeast, Mid-Atlantic and the Southeast, Thu, Dec 31.
- Heavy snow across portions of the Pacific Northwest, Wed, Dec 30.
- Heavy snow across portions of the Pacific Northwest, the Northern Rockies, and the Northern Great 
Basin, Wed-Thu, Dec 30-Dec 31.
- Heavy snow across portions of the Northern/Central Plains, the Upper Mississippi Valley and the 
Great Lakes, Tue-Wed, Dec 29-Dec 30.
- 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.
- Flooding occurring or imminent across portions of the Pacific Northwest.
- Heavy precipitation across portions of mainland Alaska, Mon-Tue, Dec 28-Dec 29.
 
Detailed Summary:

Much of the CONUS will experience hazardous weather during the medium range period (Monday, 
December 28th - Friday, January 1st). A potent area of surface low pressure is forecast to produce 
heavy snowfall over interior portions of the Northeast on Monday, particularly over the 
Adirondacks. Heavy snow also remains a threat downwind of lake Ontario. An upper-level low will 
enter the West coast on Monday, bringing with it the likelihood for heavy snow to the Sierra and 
heavy rain to the surrounding low elevations.

The aforementioned system is forecast to restrengthen and generate a low pressure system over the 
Southern Plains on Tuesday. This system will go on to produce a swath of heavy snowfall from 
Nebraska to Michigan's Upper Peninsula on Tuesday and Wednesday. Heavy precipitation is likely to 
stretch from the Central Plains to the Great Lakes on Tuesday into Wednesday, while heavy rain is 
expected across the Central/Southern Plains and into the Middle/Lower Mississippi Valley on 
Tuesday. The focus for heavy rain is expected to shift eastward into the Lower/Middle 
Mississippi/Tennessee Valleys and Southeast on Wednesday. As the low pressure system deepens and 
moves into the Midwest and eastern U.S. on Thursday (New Years Eve), it will generate heavy 
rainfall across the eastern seaboard from the Carolinas up to New England. Heavy precipitation is 
possible over parts of southern Maine and northern Vermont/New Hampshire as the system moves off 
into the Canadian maritime on Friday (New Years Day). We're monitoring the possibility of a heavy 
rain event occurring over the coastal California/Oregon border between next Wednesday and Thursday 
as a slow moving low pressure system approaches from the Pacific. This is also an area that is 
currently experiencing a severe drought, so additional hazards may occur.

Meanwhile in Alaska, while the Aleutians and mainland west coast may experience some high winds on 
Saturday and Sunday as a very deep area of low pressure moves itself into the Bering Sea. Heavy 
precipitation is also a threat over the eastern portion of the Kenai Peninsula on Monday and 
Tuesday as moisture overspreads a surface front associated with the Bering Sea low.

Kebede