US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
449 PM EDT Thu May 06 2021
 
Valid Sunday May 09 2021 - Thursday May 13 2021
 
Hazards:
- Heavy rain across portions of the Southeast, the Lower Mississippi Valley, the Southern Plains, 
and the Tennessee Valley, Sun, May 9 and Tue-Wed, May 11-May 12.
- Heavy rain across portions of the Middle Mississippi Valley, the Lower Mississippi Valley, the 
Central Appalachians, the Ohio Valley, and the Tennessee Valley, Sun, May 9.
- Heavy rain across portions of the Southeast, the Southern Appalachians, and the Tennessee Valley, 
Mon, May 10.
- Flooding occurring or imminent across portions of the Southern Plains.
 
Detailed Summary:

The primary concern through the medium-range forecast period (Sunday, May 9th through Thursday, May 
13th) will be for multiple areas of heavy rain over the eastern half of the U.S. A low pressure 
center over the Central High Plains will move northeast to the Mid-Atlantic on Sunday. Widespread 
heavy rain is likely along a warm front extending eastward across the Ohio Valley and along a 
trailing cold front extending to the southwest through the Lower Mississippi Valley and Southern 
Plains. As the cold front continues to the east on Monday, heavy rain will be likely from southern 
Alabama and the western Florida Panhandle northeastward into Georgia. The cold front will stall 
along the Gulf Coast on Tuesday as an area of low pressure develops over southwest Texas. This low 
will move to the east across the Lower Mississippi Valley on Wednesday and into the Atlantic off 
the coast of South Carolina on Thursday. Rich Gulf moisture will overrun the quasi-stationary front 
ahead of the low as it moves eastward into the Southeast. Heavy rain is likely along this boundary 
as well as along a trailing cold front from the Southern Plains east across the Lower Mississippi 
Valley Tuesday and Wednesday. The cold front will continue deeper across the Southeast and into 
Florida on Thursday as the low lifts to the north along the Eastern Seaboard. Additional heavy rain 
is possible from the Southeast north through the Mid-Atlantic, but model differences with respect 
to the placement of the heaviest rainfall preclude an outlook area at this time. Previous heavy 
rain across much of the Southeast has contributed to high soil moisture, leaving many of these 
areas susceptible to flooding from the additional heavy rainfall through the period.

Elsewhere, upslope flow behind the cold front moving southward over the Central and Southern Plains 
on Sunday along with a trough of low pressure moving southeastward over the Northern and Central 
Rockies will lead to the chance for heavy rain across the Central High Plains Sunday and Monday. An 
outlook area was not included due to model differences in the placement of the heaviest rainfall, 
which should remain isolated. Snow is also likely for portions of the Northern and Central Rockies, 
but significant snow totals are not expected and the snow should mostly remain isolated to the 
higher peaks of the Wind River Range and Big Horn Mountains in Wyoming as well as the Front Range 
of Colorado.

For Alaska, a low pressure system will move along the coast off the Alaskan Peninsula Sunday into 
Monday. A second low pressure system will move along the Aleutian Islands Wednesday into Thursday. 
Rainfall is possible from the Aleutians east into southern Alaska with both systems, particularly 
across the Alaskan Peninsula, but the forecast amounts are below a hazardous threshold at this time.

Putnam