US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
301 PM EST Thu Nov 19 2020
 
Valid Sunday November 22 2020 - Thursday November 26 2020
 
Hazards:
- Heavy precipitation across portions of the Lower Great Lakes, Sun, Nov 22.
- Heavy rain across portions of the Lower/Middle Mississippi Valley, the Tennessee/Ohio Valleys, 
and the Great Lakes, Tue, Nov 24.
- Heavy snow across portions of the Pacific Northwest and the Northern Great Basin, Tue, Nov 24.
- Flooding occurring or imminent across portions of the Southeast and the Mid-Atlantic.
- Heavy precipitation across portions of mainland Alaska, Wed, Nov 25.
- Heavy precipitation across portions of the Alaska Panhandle, Mon, Nov 23.
- High winds across portions of the Alaska Panhandle and mainland Alaska, Mon-Tue, Nov 23-Nov 24.
- High significant wave heights for coastal portions of the Alaska Panhandle, Tue, Nov 24.
 
Detailed Summary:

A series of upper-level disturbances will be the impetus for hazardous weather over the CONUS 
during the medium range period (Sunday, November 22nd - Thursday, November 26th). The first wave of 
low pressure is forecast to descend over the central U.S. on Saturday. It will go on to develop a 
surface low which will produce heavy precipitation downwind of the Lower Great Lakes on Sunday. 
There's a chance for heavy rain/snowfall due to lake effect enhancement. As this system pushes off 
into the Atlantic, another one will swing in behind it over the Central Plains on Monday. The 
frontal system associated with this shortwave will be the focus for heavy rainfall across the 
Midwest and Mid-South on Tuesday. Due to the potential for a split flow pattern, heavy rainfall 
could extend into the Southeast and Southern Appalachians on Wednesday. This depends on the track 
and intensity of the potential southern stream system.

Another trough is forecast to dive down into the Pacific Northwest on Tuesday. This system will 
produce heavy snowfall over the northern Cascades before also potentially splitting into two 
separate streams. There's model uncertainty with if and how this will occur at the moment. 
Temperatures will remain around normal for the U.S. throughout the medium range.

In Alaska, an upper-level trough will produce some heavy precipitation over the southern Panhandle 
on Monday. Behind this, a more potent low will generate heavy precipitation, high winds and 
significant waves from the Prince William Sound down to the southern Panhandle between Monday and 
Tuesday.

Kebede