US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
405 PM EDT Fri Apr 16 2021
 
Valid Monday April 19 2021 - Friday April 23 2021
 
Hazards:
- Heavy rain across portions of the Southeast, Mon-Tue, Apr 19-Apr 20. 
- Heavy rain across portions of the Lower Mississippi Valley and the Southern Plains, Fri, Apr 23.
- Flooding possible across portions of the Southeast and the Lower Mississippi Valley.
- Flooding occurring or imminent across portions of the Southeast and the Lower Mississippi Valley.
- Much below normal temperatures across portions of the Plains, Tue-Wed, Apr 20-Apr 21.
- Much below normal temperatures across portions of the Central/Southern Plains and the 
Middle/Lower Mississippi Valley, Wed, Apr 21.
 
Detailed Summary:

There are multiple hazard areas for heavy rain and below normal temperatures during the medium 
range forecast period (Monday, April 19 - Friday, April 23). The first area of concern will be 
across portions of Florida as multiple low pressure disturbances traverse a quasi-stationary front 
draped across the the central Florida Peninsula. Heavy rain is expected on Monday and Tuesday for 
the northern and central Florida Peninsula as the front first retreats northward on Tuesday and 
then drifts slowly southward. Widespread rainfall totals over 3-4 inches are likely. Some lingering 
heavy rain is also possible during the day Wednesday before a second, stronger cold front pushes in 
from the northwest bringing drier, continental air southward across the Peninsula by Thursday 
morning.

The second area of concern is in the central U.S. A shortwave trough will sweep through the Rockies 
and Plains beginning Sunday. The associated surface cold front may produce some accumulating 
snowfall in the Northern and Central Rockies on Monday. The heaviest snow totals are not expected 
to be particularly high and should remain isolated to the peaks of the Wind River Range, Big Horn 
Mountains, and Front Range. Some snow is also possible eastward into the Central High Plains and 
Kansas Tuesday morning, but this snow will likely be mixed with rain and any accumulations should 
remain light. However, as this system progresses across the central and eastern U.S. on Tuesday and 
Wednesday, a strong area of high pressure will fill in across the central U.S. This will contribute 
to much below normal minimum temperatures across most of the Central High Plains Tuesday morning 
and expand southward to include northern portions of the Southern High Plains and Texas as well as 
eastward into the Central Plains and Oklahoma for Wednesday morning. Widespread freezing 
temperatures are likely for northern portions of this area, and vegetation may be sensitive to 
these temperatures, particularly across central and eastern Kansas as well as southeastern 
Nebraska. 

By Friday, rain chances in the Central and Southern Plains as well as the Middle and Lower 
Mississippi Valley will rapidly increase as a shortwave approaches from the west and a surface low 
pressure center develops in the lee of the Rockies. Gulf moisture will return northward behind a 
lifting warm front and contribute to the development of widespread storms. Current forecasts 
indicate that portions of eastern Texas and most of Louisiana could receive heavy rain with totals 
of 1-2+ inches possible, but the area of heaviest rainfall remains uncertain. 

Elsewhere, strong ridging along the Pacific coast will lead to above normal highs, particularly for 
portions of central and southern California on Monday, but the departure from normal and duration 
is not considered to be hazardous. Some snow showers are possible for eastern portions of the Great 
Lakes region, New York, and interior New England as the storm system and associated cold front in 
the central U.S. moves to the east Wednesday and Thursday. Cooler temperatures are expected behind 
the cold front from the Appalachians northward into the Northeast, but these temperatures should 
not be well below normal. Cooler temperatures and some mountain snow are are also forecast for 
Montana on Thursday and Friday as a cold front pushes southeast from Canada, but the temperatures 
and snow amounts are not expected to be particularly significant at this time. 

For Alaska, no weather hazards are currently expected during this forecast period. Above normal 
temperatures will continue across the North Slope, but are not considered hazardous. Periods of 
rain and gusty winds are likely for the Aleutian Islands, Alaskan Peninsula, and Kodiak Island 
Monday through Friday due to the passage of back to back low pressure systems over the Pacific. 
There is a possibility of more significant rainfall around Wednesday, but there is not currently 
enough model consensus on coverage or amounts to introduce a hazard area at this time. 
 
Putnam