US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
319 PM EST Wed Nov 11 2020
 
Valid Saturday November 14 2020 - Wednesday November 18 2020
 
Hazards:
- Heavy precipitation across portions of California, the Pacific Northwest, and the Northern Great 
Basin, Sat-Wed, Nov 14-Nov 18.
- Heavy precipitation across portions of California, the Central Great Basin, the Pacific 
Northwest, and the Northern Great Basin, Tue-Wed, Nov 17-Nov 18.
- Heavy snow across portions of the Central Plains, the Central Great Basin, the Northern Plains, 
the Northern Rockies, the Central Rockies, and the Northern Great Basin, Sat, Nov 14.
- Heavy snow across portions of the Northern Rockies and the Northern Great Basin, Sat-Sun, Nov 
14-Nov 15.
- High winds across portions of the Central Plains, the Central Rockies, the Northern Plains, the 
Northern Rockies, the Southern Rockies, and the Southern Plains, Sat, Nov 14.
- Much below normal temperatures across portions of mainland Alaska, Sun-Tue, Nov 15-Nov 17.
 
Detailed Summary:

The busiest weather during the medium range looks to take place in the Pacific Northwest. This is 
due to an amplifying upper ridge over the North Pacific and Bering Sea that, in turn, digs an upper 
level trough over the northeast Pacific. The trough then directs copious amounts of atmospheric 
moisture at the West Coast as it taps into rich subtropical moisture. Spotty showers and mountain 
snow from the Cascades to the Northern Rockies will be common on Saturday. A new wave of low 
pressure tracks into western Washington on Sunday with a second storm approaching the region early 
week. The second storm has a better opportunity to produce heavy rainfall and mountain snow as the 
upper trough amplifies, setting up a potential atmospheric river event from northern California to 
western Washington. While rainfall/snowfall rates can be heavy at times, the steady barrage of 
subtropical moisture will blanket the Cascades and Olympics with heavy snow and soaking rainfall 
for coastal and valley locations. Elsewhere, the strong storm system that slams into the Northwest 
on Friday is likely to generate high winds in the northern Rockies and northern High Plains this 
Saturday. 

Farther east, the Great Lakes will be closely monitored as a strengthening cyclone passes through 
the region on Sunday. Latest model guidance has trended toward a stronger storm system with wind 
speeds that will be closely monitored. Should guidance continue to favor a stronger storm system, 
high wind hazards could be introduced for portions of the Great Lakes. Some locally heavy rainfall 
amounts are also possible from the mid-Mississippi Valley to the Ohio Valley on Sunday.

Over Alaska, a Gulf of Alaska low should lead to an unsettled weather pattern in the lower 
Panhandle but precipitation amounts remain below hazardous thresholds. An amplifying ridge over the 
Bering Sea Sunday causes an injection of below normal temperatures into central and east-central 
Alaska. Latest guidance has trended cold enough to warrant the issuance of a much below normal 
temperature area in portions of the central and eastern mainland. Daily anomalies from Nov 15-17 
may hover around 20 degrees below normal in these areas.

Mullinax