US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
258 PM EDT Tue May 11 2021
 
Valid Friday May 14 2021 - Tuesday May 18 2021
 
Hazards:
- Heavy rain across portions of the Central Plains, the Lower Mississippi Valley, the Southern 
Plains, the Middle Mississippi Valley, the Great Lakes, and the Ohio Valley, Sat-Mon, May 15-May 17.
- Heavy rain across portions of the Middle Mississippi Valley, the Lower Mississippi Valley, and 
the Southern Plains, Mon-Tue, May 17-May 18.
- Flooding possible across portions of the Great Lakes, the Lower Mississippi Valley, the Southern 
Plains, and the Ohio Valley.
- Flooding occurring or imminent across portions of the Great Lakes, the Lower Mississippi Valley, 
the Southern Plains, and the Ohio Valley.
 
Detailed Summary:

Much of the medium-range forecast period (Friday, May 14th through Tuesday, May 18th) should be 
relatively hazards free across the Lower 48, with the threat of active weather confined to central 
and south-central sections of the country. At the surface, a large high pressure system is forecast 
to be found across the Ohio Valley and eastern U.S. through the weekend. Meanwhile, a warm front 
situated over the Central Plains should slowly extend eastward through the Midwest by the end of 
the weekend. This warm front could be the focus of showers and thunderstorms that eventually grow 
upscale into multiple mesoscale convective complexes this weekend between central Kansas and 
northern Missouri. Thus, the threat of heavy rain from these thunderstorms extends from the Central 
Plains to the western Ohio Valley between Saturday and Monday. A few severe thunderstorms are not 
out of the question as well, but the overall magnitude of the severe threat appears low at this 
time. It is also important to note that forecast confidence is below average for the medium range 
period between the Central Plains and Ohio Valley. By Monday, a weakening upper-level low ejecting 
out of the Southwest is expected to spark thunderstorms across the Southern Plains and Lower 
Mississippi Valley. Moisture return from the western Gulf of Mexico should be sufficient and aid in 
scattered to widespread instances of heavy rain early next week across the region. Confidence is 
particularly high regarding 1+ inches of rain across north-central and eastern portions of Texas, 
with an isolated severe threat a possibility as well. Expect subtle changes to the highlighted 
heavy rain areas as confidence hopefully increases once the time period draws closer.

Temperatures across CONUS will start below average across the Southeast on Friday before warming to 
near normal by the beginning of next week. Meanwhile, high temperatures will reach upwards of 10 to 
20 degrees above average throughout the Intermountain West, Northwest, and Desert Southwest on 
Friday. The warmth is expected to remain through the forecast period, but relax slightly by Monday 
as a Pacific cold front enters the region. Little to no precipitation is expected across the West.

For Alaska, much of the area should remain relatively quiet through the weekend and into next week. 
A potent storm system may impact the Aleutians by Tuesday, but wind gusts at the moment appear to 
remain below hazardous threshold. 

Snell