US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
349 PM EDT Tue May 19 2020
 
Valid Friday May 22 2020 - Tuesday May 26 2020
 
Hazards:
- Heavy rain across portions of the central and southern Plains, Sun-Mon, May 24-May 25.
- Heavy rain across portions of southern Texas, Tue, May 26.
- Flooding possible across portions of the central Appalachians into the Mid-Atlantic, as well as 
the lower Great Lakes into the Ohio Valley.
- Flooding occurring or imminent across portions of the lower Mississippi Valley, the northern 
Plains, the northern Washington, and from the Midwest into the lower Great Lakes.
- Flooding likely across portions of western Montana into northern Idaho.
- Heavy precipitation across portions of southern Alaska, Fri-Sun, May 22-May 24.
 
Detailed Summary:

The highly amplified synoptic pattern currently across the U.S. is expected to return to a more 
typical configuration by the medium range period (Friday 5/22 - Tuesday 5/26).  The cutoff 
upper-level low over the eastern U.S. should continue to gradually weaken and then move off the 
East Coast.  This will end the threat of heavy rainfall across the interior Mid-Atlantic on Friday 
before the associated frontal wave moves out to sea on Saturday.

Over the Pacific Northwest, the arrival of the next upper-level trough should push a Pacific front 
through the northern Rockies on Friday, likely bringing a period of wet snow for the higher 
elevations of northwestern Wyoming and southwestern Montana on Friday into Saturday morning.  
Moisture ahead of the front appears to support only modest amounts of rainfall across the northern 
Plains on Saturday.  However, moisture returning from the Gulf of Mexico ahead of the cold front 
should begin to raise the threat of heavy rainfall on Sunday into Memorial Day across the central 
to southern Plains.  The front is forecast to become nearly stationary early next week across the 
southern High Plains as the highest threat of heavy rain shifts farther to the south across 
southern Texas by Tuesday.

Cooler than normal conditions are expected to spread across the northwestern U.S. toward the 
southern Plains behind the Pacific cold front in contrast with above normal temperatures across the 
Plains toward the Great Lakes ahead of the front.  Temperatures are forecast to be within 15 
degrees from normal through the medium-range period across the country.

As for Alaska, a weakening occluded cyclone is forecast to bring heavy rain across the lower 
elevations of southern coastal sections including the Kenai Peninsula from Friday into the Memorial 
Day weekend.  Snow is expected for the higher elevations.  Meanwhile, ice jam flooding will be a 
concern over the North Slope as rivers have not yet broken up, while minor snowmelt flooding is a 
possibility in central and southern parts of the mainland.  Above normal temperatures are forecast 
to persist across central Alaska up to the Brooks Range but they do not require a temperature 
hazardous area at this time.

Kong