US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
314 PM EDT Thu Apr 08 2021
 
Valid Sunday April 11 2021 - Thursday April 15 2021
 
Hazards:
- Heavy rain across portions of the Southeast, and the Lower Mississippi Valley, Tue-Thu, Apr 
13-Apr 15.
- Heavy rain across portions of central Florida, Sun, Apr 11.
- Heavy snow across portions of the Central Rockies, Tue-Wed, Apr 13-Apr 14.
- Flooding occurring or imminent across portions of the Middle Mississippi Valley and the Lower 
Mississippi Valley.
- Flooding likely across portions of the Lower Mississippi Valley.
- Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sun-Wed, Apr 
11-Apr 14.
- Much below normal temperatures across portions of mainland Alaska, Sun, Apr 11.
 
Detailed Summary:

The weather across the lower 48 during the medium range period (Sunday, April 11 - Thursday, April 
15) will be predominantly influenced by a series of Pacific systems advancing across the 
north-central states and reinforcing broad troughing from the Great Lakes to the Western U.S.. On 
Sunday, a strong low pressure system will be advancing across the Eastern states with a broad area 
of showers and thunderstorms likely from the Southeast to New England. The best chance for heavy 
rainfall potential looks to be along the trailing cold front as it shifts southward across Florida. 
The heavy rain area across parts of the central Peninsula and western coast was maintained. 

The next cold front enters the East by next Tuesday, though most of the precipitation associated 
with this system should focus along a stationary boundary draped across the Gulf Coast region. 
Another round of heavy rainfall is possible across parts of the Lower Mississippi Valley and 
Central Gulf Coast states next Tuesday-Thursday as Gulf Moisture overruns the boundary. Exact 
rainfall amounts, and whether they technically reach criteria of 1" in 24-hours, remains uncertain, 
but decided an area was warranted given much above normal rainfall the past couple of weeks and the 
likelihood additional precipitation could enhance flooding concerns. 

To the north, strong Canadian High pressure sinking southward into the Plains along with another 
upper low entering the Western U.S., could favor an upslope precipitation event Tuesday into 
Wednesday across parts of the central Rockies. There remains some uncertainty in the pattern, but 
recent guidance seems to be trending towards heavy snowfall potential, with WPC probabilities of 
greater than a quarter inch liquid equivalent up to 50-70 percent. For this reason, a small heavy 
snowfall area was introduced today across the southern WY and northern/central CO Rockies. This 
same system may favor gusty winds across parts of the Southwest Tuesday into Wednesday, but 
criteria meeting wind speeds/gusts did not seem widespread enough for an area on the hazards chart 
today. Still, the potential for high winds across this region will need to be monitored and an area 
may need to be introduced should incoming model guidance support it.

Over Alaska, arctic air entrenched over much of the mainland will maintain much below normal 
temperatures through the weekend, with moderation back towards normal expected by early next week. 
Several low pressure systems in/near the Gulf will also bring the potential for heavy precipitation 
to parts of the southern Coast region and Panhandle. Heavy snow is likely in higher elevations, 
with rain along the coast.

Santorelli