US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
405 PM EDT Tue Oct 20 2020
 
Valid Friday October 23 2020 - Tuesday October 27 2020
 
Hazards:
- Heavy rain across portions of the Central Plains, the Mid-Atlantic, the Lower Mississippi Valley, 
the Central Appalachians, the Tennessee Valley, the Great Lakes, the Middle Mississippi Valley, the 
Northeast, the Southern Plains, and the Ohio Valley, Sun-Mon, Oct 25-Oct 26.
- Heavy snow across portions of the Pacific Northwest, Fri, Oct 23.
- Heavy snow across portions of the Northern Plains, the Northern Rockies, and the Northern Great 
Basin, Sat, Oct 24.
- Heavy snow across portions of the Central Rockies, the Central Plains, the Central Great Basin, 
the Northern Plains, and the Northern Rockies, Sun, Oct 25.
- Flooding possible across portions of the Southeast.
- Flooding occurring or imminent across portions of the Lower Mississippi Valley.
- Much below normal temperatures across portions of the Central Plains, the Central Rockies, the 
Great Lakes, the Central Great Basin, the Northern Plains, the Southern Plains, the Northern 
Rockies, the Southern Rockies, the Middle Mississippi Valley, the Northern Great Basin, the Upper 
Mississippi Valley, and the Pacific Northwest, Fri-Tue, Oct 23-Oct 27.
- Heavy precipitation across portions of the Alaska Peninsula and southwestern Alaska, Fri, Oct 23.
- Heavy precipitation across portions of the Alaska Panhandle and coastal Southcentral Alaska, 
Sun-Mon, Oct 25-Oct 26.
- High winds across portions of the Alaska Peninsula, Fri, Oct 23.
 
Detailed Summary:

Broad troughing over the western 2/3rds of North America will lead to reinforcing shots of cold air 
into much of the West and Plains late this week into next week. The rather wintry pattern will 
bring in well below normal temperatures to the area with record cold likely for some areas. This 
translates to temperatures of 20-40 degrees below normal, focused over Montana, and 15-30 degrees 
below normal from the Pacific Northwest to the Plains and Corn Belt/Upper Midwest. Daytime 
temperatures will generally be near to below freezing and overnight lows below zero in colder 
locations to the 10s/20s in the central states. Heavy snow may accompany a lead system early in the 
period over the Cascades, moving eastward and southward this weekend. Snowfall will be heaviest in 
the mountains but will also spread into the valleys out of Montana/Idaho and through Wyoming into 
the western Plains. Significant accumulations are possible. To the east, as the system exits the 
Plains late this weekend, heavy rain may expand across the lower Mississippi Valley northeastward 
through the Ohio Valley to the Midwest and eastern Great Lakes as moisture increases off the Gulf. 

Over Alaska, a robust area of low pressure is forecast to lift across the central Aleutians into 
the Bering Sea Friday with its triple point over the Alaska Peninsula. Strong southeast flow ahead 
of the warm front will bring an area of high winds to southeast-facing areas of the AKPen toward 
the western side of Cook Inlet along with heavy low-elevation rain. Some localized heavy snow is 
also possible over southwestern areas of the mainland as the system moves to the northeast. As the 
triple point low moves into the Gulf, upper pattern will maintain onshore flow for a few days, 
which could lead to heavy rain over southeastern portions of the mainland (Prince William Sound 
eastward) through Yakutat and across nearly the entire Panhandle next Sun/Mon. Heaviest rainfall 
will be along the coast with a bit less through the Inland Passage. Heavy snow is likely over 
higher elevations. To the north, well above normal temperatures are likely for the North Slope and 
northwestern areas, but was not deemed hazardous for these values (mainly in the 20s) and thus not 
included on the map. 

Fracasso