US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
410 PM EDT Tue May 25 2021
 
Valid Friday May 28 2021 - Tuesday June 01 2021
 
Hazards:
- Heavy rain across portions of the Plains, and the Mississippi Valley,  Sun-Tue, May 30-Jun 1.
- Heavy rain across portions of the Mid-Atlantic, the Central Appalachians, and the Ohio Valley, 
Fri, May 28.
- Flooding possible across portions of the Middle Mississippi Valley.
- Flooding occurring or imminent across portions of the Central Plains, the Middle Mississippi 
Valley, the Lower Mississippi Valley, and the Southern Plains.
- Flooding likely across portions of the Northern Rockies.
- Much above normal temperatures across portions of California, the Central Great Basin, the 
Pacific Northwest, and the Northern Great Basin, Mon-Tue, May 31-Jun 1.
- Heavy rain across portions of the Alaska Panhandle and mainland Alaska, Fri-Sun, May 28-May 30.
 
Detailed Summary:

In the medium-range forecast period, which includes the Memorial Day weekend, there is a wavy front 
extending from the Mid-Atlantic to the Ohio Valley then southwestward to the Southern Plains.  The 
front has a wave of low pressure over the Mid-Atlantic that will produce rain over the region on 
Friday.  The wave of low pressure moves offshore on Saturday and the rain diminishes.  The system 
will produce enough rain to have an area of heavy rain over parts of the Mid-Atlantic on Friday.   

A second wave along the front over the Ohio Valley on Friday will have stronger wind associated 
with the low over the Great Lakes on Friday and Saturday, with Lake Erie having the high wind the 
longest.  The wind speed will not meet the criteria for an area of high wind.   

The tail end of the front mentioned above will move over the Central/Southern Plains on Sunday.   
The air over the Central/Southern Plains will become unstable, aiding in the development of a MCS 
over parts of the Central/Southern Plains on Sunday, producing heavy rain over the area.  An area 
of heavy rain is depicted over the region on Sunday.  

A second front moving out of the Northern High plains will move over the Central/Southern Plains on 
Monday into Tuesday.  Showers and thunderstorms will develop along and near the boundary that will 
produce rain through Tuesday.  The area of heavy rain will fall over parts that rain that fell on 
Sunday.   The location of heavy rain will extend to a greater extent over the Central/Southern 
Plains through Tuesday.  An area of heavy rain is depicted over the region through Tuesday.

 Upper-level ridging will develop over the Pacific Northwest into California on Sunday into 
Tuesday. The upper-level ridging will allow temperatures to get into the upper 80s over the 
Northwest and the 90s into the 100s over parts of California.  With this in mind, an area of much 
above normal temperatures is directed over the place from Monday into Tuesday.   Furthermore, high 
pressure over the Eastern Pacific and a heat trough over California will produce strong winds 
offshore and near the coast. Still, at this time, the wind speed is below the criteria for an area 
of high winds.  However, the situation will need to have an eye kept on the wind to see if the wind 
will meet the criteria later.  

For Alaska, an area of low pressure along the Aleutians on Friday will move into the Gulf of Alaska 
by Sunday. Moisture associated with the low will stream into the coastal regions producing heavy 
rain from parts of the Kenai Peninsula eastward to the Inside Passage on Saturday and Sunday.  At 
this time, the precipitation seems to be rain, but some of the higher peaks will still get snow. 

Ziegenfelder