US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
345 PM EDT Mon Apr 27 2020
 
Valid Thursday April 30 2020 - Monday May 04 2020
 
Hazards:
- Heavy rain across portions of the Mid-Atlantic, the Northeast, and the Great Lakes, Thu-Fri, Apr 
30-May 1.
- Flooding possible across portions of the Middle Mississippi Valley, the Great Lakes, and the Ohio 
Valley.
- Flooding occurring or imminent across portions of the Southeast, the Lower Mississippi Valley, 
the Southern Plains, the Upper Mississippi Valley, and the Northern Plains.
- Flooding likely across portions of the Southeast and the Northern Rockies.
- Much above normal temperatures across portions of the Central Plains, the Central Great Basin, 
the Northern Plains, the Northern Rockies, the Central Rockies, the Northern Great Basin, and the 
Southwest, Thu-Fri, Apr 30-May 1.
- Much above normal temperatures across portions of the Central Plains, the Central Rockies, the 
Central Great Basin, the Southern Rockies, the Southern Plains, and the Southwest, Thu-Sat, Apr 
30-May 2.
- Much above normal temperatures across portions of the Central Plains and the Southern Plains, 
Fri-Sun, May 1-May 3.
 
Detailed Summary:

The synoptic pattern through the medium-range period (Thurs, Apr 30 to Monday, May 4) is 
highlighted by a large upper trough in the Gulf of Alaska, an upper ridge axis over the Southwest 
and Great Plains, and lingering troughing over the Ohio Valley and Northeast. The most notable 
hazard in this period is a sprawling area of much above normal temperatures centered across the 
Southwest and into the south-central High Plains. Widespread temperatures in the 80s and 90s are 
expected with come locations reaching triple digits. California, the Great Basin, and northern High 
Plains will start the period with the warmest temperature anomalies but trend cooler as the large 
area of troughing in the Gulf of Alaska directs cooler Pacific air towards these regions. Drier 
than normal conditions are also possible in the Southwest and South Central U.S. while on shore 
flow allows for a wetter pattern from the Pacific Northwest to parts of the Northern Rockies.

The troughing pattern in the East makes for an active setup along the East Coast, most notably 
Thursday and into Friday. The start of the period will be highlighted by a highly amplified upper 
level trough tracking towards the Eastern Seaboard. Large scale vertical ascent coupled with a low 
level jet transporting copious amounts of moisture up the East Coast will trigger heavy rainfall 
from the Mid-Atlantic coast to the Northeast on Thursday and into Friday morning. As the ridge out 
west flattens due to the effects of the intense Gulf of Alaska trough, expect Pacific disturbances 
to track through the Northwest and into the Nation's Heartland in days 5-7. Guidance does suggest 
the potential for showers and thunderstorms from the Central Plains to the Ohio Valley during this 
time frame, but whether precipitation totals reach heavy rainfall criteria is low confidence at 
this time.

Over Alaska, the state should find itself north of the anomalously deep Gulf of Alaska/northeast 
Pacific trough and building high pressure to the north. The storm track may still lead to 
occasional periods of rain throughout the Panhandle, but daily totals are forecast to remain below 
heavy rainfall criteria. High pressure over the northern mainland combined with the southerly storm 
track should keep high winds and any active weather south of the mainland for the much of the 
medium range. Lastly, pockets of abnormally mild temperatures in the southwest and slightly below 
normal temperatures in east-central Alaska will be common but should also fall short of much 
above/below normal criteria.

Mullinax