US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
330 PM EST Mon Nov 16 2020
 
Valid Thursday November 19 2020 - Monday November 23 2020
 
Hazards:
- Heavy precipitation across portions of California, the Pacific Northwest, and the Northern Great 
Basin, Thu, Nov 19.
- Heavy rain across portions of the Pacific Northwest, Sun-Mon, Nov 22-Nov 23.
- Heavy rain across portions of the Central/Southern Plains, the Mississippi Valley, the Tennessee 
Valley, the Great Lakes, and the Ohio Valley, Sat-Sun, Nov 21-Nov 22.
- Heavy snow across portions of the Pacific Northwest, the Northern Rockies, and the Northern Great 
Basin, Thu-Fri, Nov 19-Nov 20.
- Flooding occurring or imminent across portions of the Southeast and the Mid-Atlantic.
- Heavy precipitation across portions of mainland Alaska and the Aleutians, Fri, Nov 20.
- High winds across portions of mainland Alaska and the Aleutians, Fri, Nov 20.
 
Detailed Summary:

Weakening upper-level energy and accompanying weak onshore flow will aid in producing Heavy Snow 
over the Cascades and the Northern Rockies on Thursday and Friday.  Heavy Precipitation will also 
develop over the Southern Cascades and into parts of the Sierra Nevada mountains on Thursday.   
Overnight Friday, the onshore flow ends and the precipitation will come to an end, too.

Meanwhile on Friday, a front extending from the Great Lakes to the Southern High Plains will become 
stationary through Sunday.  Moisture will pool along the boundary and aid in producing Heavy Rain 
over parts of the Great Lakes roughly southward to parts of the Southern Plains and Lower 
Mississippi Valley on Saturday and Sunday.  Another area of Heavy Rain could develop along the 
front over the Lower Mississippi and Tennessee Valleys on Monday.  However, there is a lot of 
spread in the model guidance providing low confidence in depicting an area on the Hazards Chart at 
this time.  

In addition on Friday, a front over the Eastern Pacific will move eastward and will start to come 
onshore over the Pacific Northwest on Saturday.  Moisture flowing parallel to the front will move 
onshore as well producing Heavy Rain over the Pacific Northwest Coast on Sunday into Monday. 

Furthermore, there is an area of temperature that will be 12 to 20 degrees above normal from parts 
of the Southern Rockies to the Great Lakes on Thursday to Sunday.  However, at this time of the 
year, temperatures in the 60s and 50s are not a hazard. 

A series of lows will move into the Aleutians and the Alaska Peninsula from Thursday into Sunday.  
The systems will have a weak moisture component associated with the storms.  In general, the hazard 
criteria will not be met.  On Friday, the pressure gradient will be strong enough to depict an area 
of High Wind over the Alaskan Peninsula into the Kenal Peninsula on Friday.  There will also be 
enough moisture to produce an area of Heavy Precipitation over the same region on Friday.

Ziegenfelder