US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
427 PM EDT Wed Mar 31 2021
 
Valid Saturday April 03 2021 - Wednesday April 07 2021
 
Hazards:
- Heavy snow across portions of the Central Great Basin and California, Tue-Wed, Apr 6-Apr 7.
- Flooding possible across portions of the Southeast, the Mid-Atlantic, the Lower Mississippi 
Valley, and the Southern Appalachians.
- Flooding possible across portions of the Southeast, the Mid-Atlantic, the Southern Appalachians, 
and the Tennessee Valley.
- Flooding possible across portions of the Southeast and the Mid-Atlantic.
- Flooding occurring or imminent across portions of the Southeast, the Lower Mississippi Valley, 
the Southern Appalachians, the Ohio Valley, and the Tennessee Valley.
- Flooding occurring or imminent across portions of the Southeast, the Lower Mississippi Valley, 
the Southern Appalachians, the Ohio Valley, and the Tennessee Valley.
- Flooding occurring or imminent across portions of the Lower Mississippi Valley, the Ohio Valley, 
and the Tennessee Valley.
- Flooding likely across portions of the Ohio Valley.
- Much above normal temperatures across portions of California and the Southwest, Sat-Mon, Apr 
3-Apr 5.
- Much above normal temperatures across portions of the Southern Plains, Tue-Wed, Apr 6-Apr 7.
- Much below normal temperatures across portions of the Southeast, the Mid-Atlantic, the Southern 
Appalachians, and the Tennessee Valley, Sat, Apr 3.
- Heavy snow across portions of mainland Alaska, Sat-Sun, Apr 3-Apr 4.
 
Detailed Summary:

At the beginning of the forecast period (Saturday, April 3rd), the weather pattern over much of the 
U.S. will be dominated by large scale ridging anchored over the Plains, with an upper low departing 
the Maine coast. Accordingly, the predominant hazard during days 3-7 over the CONUS are temperature 
anomalies associated with this pattern. On Saturday morning in the Tennessee Valley, cool high 
pressure centered over the region will meander southeast through the day. Another shot of below 
average temperatures (10-15 degrees) is likely across the Piedmont into northern Georgia, just past 
the climatological date of last expected spring freeze. Given the vulnerability of newly planted 
crops in the region, have maintained a Much Below Normal temperature area for April 3rd. The cooler 
temperatures will moderate to above freezing by Sunday. Elsewhere, summer-like warmth could be 
problematic over the Desert Southwest into the Southern Plains through the forecast period as the 
upper level ridge builds and eventually migrates eastward. High temperatures could hit 100 degrees 
in Death Valley and further east into the Phoenix area over the weekend. Southwesterly flow will 
usher in warmth to west Texas April 6th-7th, bringing with it temperatures 15-20 degrees above 
normal. Temperatures also approach the 90â€s in central Texas as strong southerly flow pushes in, 
but the warm temperatures in this area are more in line with climatology and thus not considered 
hazardous.  

Precipitation wise, the threat of heavy snow remains in Alaska April 3rd - 4th, as a frontal system 
traverses the Bering Sea over the mainland. Some gusty winds may accompany the storm, but will 
remain below hazardous levels. Further south on days 5-6, shortwave energy is forecast to translate 
south along the coast of British Columbia towards the Pacific Northwest, in conjunction with a 
cut-off low lifting towards the coast of California. As with yesterday, solutions differ greatly as 
to how these features will interact, in part due to upstream shortwave interactions with low 
predictability at this range. However, the general pattern of a slow moving trough across the West 
Coast would favor a bout of heavy mountain snow and lower elevation rain. Corroborated by an 
ensemble signal for accumulating snow, a heavy snow area was introduced to the Sierra April 
6th-7th. On day 7, there is some ensemble support for convectively driven heavy rain associated 
with a frontal system in the upper Midwest ahead of a strong moisture advection regime. However, 
uncertainty regarding the progression of the upper trough, coupled with the inherent mesoscale 
details of this event precludes the need for a Heavy Rain area at this time. 



Asherman