US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
355 PM EDT Fri Oct 16 2020
 
Valid Monday October 19 2020 - Friday October 23 2020
 
Hazards:
- Heavy rain across portions of the Middle Mississippi Valley, the Lower Mississippi Valley, the 
Central Appalachians, the Ohio Valley, and the Tennessee Valley, Mon, Oct 19.
- Heavy snow across portions of the Northern Plains and the Northern Rockies, Wed, Oct 21.
- Flooding occurring or imminent across portions of the Lower Mississippi Valley.
- Much below normal temperatures across portions of the Upper Mississippi Valley, the Northern 
Plains, and the Northern Rockies, Mon-Tue, Oct 19-Oct 20 and Thu-Fri, Oct 22-Oct 23.
- Much below normal temperatures across portions of the Central Plains, the Middle Mississippi 
Valley, the Upper Mississippi Valley, and the Northern Plains, Mon-Tue, Oct 19-Oct 20.
 
Detailed Summary:

The medium range (Mon. Oct 19 - Fri. Oct 23) can be summarized by anomalous ridging over the East 
Coast and much of the southern tier, while a deep upper trough sets up across the North Central 
U.S. and central Canada. The bulk of the hazardous weather potential across the Lower 48 is 
forecast to be along the periphery of the base of the upper trough with wintry weather expected in 
the northern Rockies. The first round of below normal temperatures moderates Tuesday and Wednesday 
in the Midwest, but a second upper-level trough looks to push through the Rockies by Wednesday. 
There may be another round of heavy snow in the northern Rockies Wednesday followed by another 
surge of chilly temperatures to close out the work-week. Farther south, a frontal boundary draped 
over the Ohio and mid-Mississippi Valleys becomes the trigger for showers and thunderstorms on 
Monday that could produce heavy rain. 

In the tropics, ensemble guidance is keying in on potential tropical development in the heart of 
the Caribbean. The NHC 5-day outlook as of this afternoon shows a 30% chance of development. The 
progress of this disturbance will be closely monitored through the weekend and into next week.

Over Alaska, an amplifying upper level trough over the upper Peninsula and most of the mainland is 
likely to be the primary weather driver across the state in the medium range. To start the week, 
the Panhandle can expect wetter than normal conditions but precipitation amounts are forecast to be 
below hazardous thresholds. Drier conditions are likely to return in the Panhandle later in the 
week. Most of the mainland can anticipate a dry and mild stretch of weather into much of next week. 
While there is ensemble support for a storm system in the North Pacific mid-late week, the storm's 
strength, timing, and position relative to the Peninsula and southern coast remain low confidence 
due to high variability in ensemble guidance.

Mullinax