US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
351 PM EDT Fri Sep 25 2020
 
Valid Monday September 28 2020 - Friday October 02 2020
 
Hazards:
- Heavy rain across portions of the Great Lakes, the Northeast, the Mid-Atlantic, the Appalachians, 
and the Southeast, Tue-Wed, Sep 29-Sep 30.
- Flooding occurring or imminent across portions of the Southeast.
- Much above normal temperatures across portions of California, the Great Basin, and the Pacific 
Northwest, Mon-Fri, Sep 28-Oct 2.
- Much below normal temperatures across portions of the Central/Northern Plains, the Middle/Upper 
Mississippi Valley, and the Great Lakes, Thu-Fri, Oct 1-Oct 2.
- Heavy precipitation across portions of mainland Alaska, Tue-Fri, Sep 29-Oct 2.
- Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Mon-Fri, Sep 
28-Oct 2.
- High winds across portions of mainland Alaska, Tue-Wed, Sep 29-Sep 30.
 
Detailed Summary:

During the medium range period (Monday, Sep 28 - Friday, Oct 2), a deep upper-level trough will be 
slow-moving across the central to eastern U.S., while upper-level ridging builds across the West. 
This upper-level pattern should lead to warmer than average temperatures across the West. Records 
for warm lows and highs are possible particularly across California and southern Oregon, with 
temperatures 5 to 15 degrees above normal. The Desert Southwest could see highs above 100 degrees, 
but only a few degrees above average for this time of year. Warmth spreads into the Pacific 
Northwest and Great Basin, but highs in the 70s and 80s are not considered hazardous. 

On the other hand, cooler than normal temperatures are forecast for the central U.S. underneath the 
trough and behind a couple of cold fronts. These cooler temperatures will spread from the Rockies 
and Plains on Monday toward the Mississippi/Tennessee/Ohio Valleys by Tuesday and Wednesday, and 
eventually knock down above normal temperatures in the East as the week progresses. An area of Much 
Below Normal Temperatures was delineated on the Hazards graphic across portions of the 
Northern/Central Plains to Upper Midwest, where morning low temperatures could get into the 30s and 
cause the first frost or freeze of the season by Thursday/Friday. This seemed to be the most 
hazardous aspect of these temperatures more reminiscent of mid- or late fall.

A leading cold front moving across the East is expected to provide a focus for potentially heavy 
rainfall. Model guidance is not too agreeable yet as to where the heaviest rainfall will occur and 
the exact timing, as it depends on the frontal position, which in turn depends on the axis and 
orientation of the upper-level trough. But the potential is there for heavy rainfall stretching 
across much of the Eastern Seaboard. The highest threat seems to be on Tuesday and Wednesday, 
though some rain is possible Monday in the Southeast and lingering Thursday in the Northeast. 
Generally dry weather is forecast across the West underneath the ridge, and additional fire weather 
concerns may develop there.

Over Alaska, heavy precipitation is forecast in the south-central part of the state as potent 
surface lows move across the Gulf of Alaska. While the entire Gulf Coast may not see heavy 
precipitation constantly through the period, multiple rounds of precipitation are possible there 
next week. Along with the precipitation, high winds are a threat over portions of Kodiak Island and 
the Kenai Peninsula in the vicinity of Cook Inlet, currently expected late Tuesday into early 
Wednesday but dependent on the timing and track of the first surface low. The Bristol Bay region 
may also see some gusty winds with that system. 

Tate