US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
427 PM EDT Wed Apr 22 2020
 
Valid Saturday April 25 2020 - Wednesday April 29 2020
 
Hazards:
- Heavy precipitation across portions of the Pacific Northwest, Sun-Mon, Apr 26-Apr 27.
- Heavy precipitation across portions of New England, Sun, Apr 26.
- Heavy rain across portions of the Southern Appalachians, the Mid-Atlantic, the Central 
Appalachians, and the Ohio Valley, Wed, Apr 29.
- Heavy rain across portions of the Great Lakes, the Mid-Atlantic, the Northeast, the Central 
Appalachians, and the Ohio Valley, Sat-Sun, Apr 25-Apr 26.
- Flooding possible across portions of the Lower Mississippi Valley and the Southern Plains.
- Flooding occurring or imminent across portions of the Lower Mississippi Valley, the Northern 
Plains, the Tennessee Valley, the Middle Mississippi Valley, the Upper Mississippi Valley, and the 
Southeast.
- Flooding likely across portions of the Southeast, the Northern Plains, and the Tennessee Valley.
- Much above normal temperatures across portions of the Central Plains, the Central Rockies, the 
Central Great Basin, the Southern Plains, the Northern Great Basin, the Southern Rockies, 
California, the Northern Rockies, the Pacific Northwest, and the Southwest, Sat-Wed, Apr 25-Apr 29.
- Much below normal temperatures across portions of the Northeast, the Central Appalachians, the 
Tennessee Valley, the Mid-Atlantic, the Southern Appalachians, the Great Lakes, and the Ohio 
Valley, Sun-Mon, Apr 26-Apr 27.
- High winds across portions of the Alaska Panhandle, Sun-Mon, Apr 26-Apr 27.
- High winds across portions of the Aleutians, Tue-Wed, Apr 28-Apr 29.
- Much below normal temperatures across portions of mainland Alaska, Sat-Sun, Apr 25-Apr 26.
 
Detailed Summary:

The medium-range period (Sat, Apr 25 to Wed, Apr 29) in the West is headlined by a deep upper level 
trough in the Gulf of Alaska while a strong ridge of high pressure takes control of the Southwest. 
A dome of much above normal temperatures originating in the Desert Southwest will spread north and 
east into northern California, the Great Basin, and the Four Corners region throughout the period. 
High temperatures are forecast to soar into the triple digits for the first time this year in 
portions of the Desert Southwest by week's end and continue into next week, making it the first 
heat wave of the season for the region. By mid-week, California and the Great Basin should 
experience the warmest conditions versus normal. To the north, a steady stream of Pacific moisture 
will be aimed at the Pacific Northwest. The heaviest round of precipitation looks to arrive Sunday 
and continue into Monday as a frontal system pushes across the region. The primary precipitation 
type will be rain but some heavy higher elevation snowfall in the Cascades is also possible.

Further east, a series of upper level disturbances will rotate through the eastern half of the 
Lower 48. An upper level feature exiting the Rockies will track east and deepen while doing so. The 
result will be blossoming areas of showers and thunderstorms from the Lower Mississippi Valley to 
the Southeast on Saturday. Some thunderstorms in the Southeast could be severe Saturday afternoon. 
The storm will head for the central Appalachians late Saturday and by Sunday, a coastal low will 
form off the East Coast making for a wet, dreary, and gusty Sunday across the Mid-Atlantic and 
Northeast. The prolonged fetch of Atlantic moisture has led to model guidance keying in on an area 
of heavy rain over the Northeast and interior Mid-Atlantic, but there are still some discrepancies 
on exact placement of heaviest rainfall due to differences in storm track. To the north, the higher 
elevations of New England could receive heavy snowfall while lower elevations see rain. This has 
resulted in the addition of a heavy precipitation area over parts of the northern Appalachians for 
Sunday. Lastly, the signal for yet another upper level trough ushering in more unsettled weather 
across the eastern half of the country mid-week is coming into focus but operational model guidance 
remain at odds on the speed of the trough and the amount of precipitation at its disposal. For now, 
confidence is highest in the potential for heavy rain over the central Appalachians. Additional 
threat areas could be drawn as early as tomorrow should confidence increase in hazardous weather 
impacts next Tuesday and Wednesday. 

Over Alaska, an area of cold high pressure looks to keep much below normal temperatures in the 
forecast over eastern Alaska this weekend. Temperatures will moderate across the eastern mainland 
next week. To the south, a pair of occluded storm systems will slam into the Panhandle both this 
weekend and the first half of the week. Plenty of precipitation is in the forecast but 
precipitation rates are not forecast to become excessive at this time. Should trends become wetter, 
there may be a need for a heavy rain or precipitation area in the future forecasts. However, high 
winds along the Panhandle coast are possible Sunday and potentially into Monday as well. By 
forecast days 6-7, a powerful upper low in the northwest Pacific may reach the Aleutians and force 
winds to become strong, especially for the western most islands. 

Mullinax