US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
320 PM EST Thu Feb 20 2020
 
Valid Sunday February 23 2020 - Thursday February 27 2020
 
Hazards:
- Heavy precipitation across portions of the Pacific Northwest, Sun-Mon, Feb 23-Feb 24.
- Heavy rain across portions of the Central Plains, the Middle Mississippi Valley, and the Ohio 
Valley, Sun-Mon, Feb 23-Feb 24.
- Heavy rain across portions of the Southeast, the Mid-Atlantic, the Southern Appalachians, and the 
Tennessee Valley, Mon-Tue, Feb 24-Feb 25.
- Heavy snow across portions of the Pacific Northwest, the Northern Rockies, and the Northern Great 
Basin, Sun-Mon, Feb 23-Feb 24.
- Heavy snow across portions of the Southern/Central Rockies, the Central Great Basin, the Central 
Plains, and the Southwest, Sun, Feb 23.
- Heavy snow across portions of the Central/Northern Plains, the Middle/Upper Mississippi Valley, 
and the Great Lakes, Tue-Thu, Feb 25-Feb 27.
- Flooding occurring or imminent across portions of the Lower Mississippi Valley, the Tennessee 
Valley, the Middle Mississippi Valley, the Mid-Atlantic, the Southeast, and the Ohio Valley.
- Flooding likely across portions of the Southeast.
- Much below normal temperatures across portions of the Plains, the Rockies, the Mississippi 
Valley, the Central Great Basin, and the Southwest, Tue-Thu, Feb 25-Feb 27.
- Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Tue-Thu, Feb 
25-Feb 27.
- High winds across portions of mainland Alaska and the Aleutians, Mon-Tue, Feb 24-Feb 25.
 
Detailed Summary:

The medium range period begins on Sunday with an upper-level low over the Four Corners region, 
which could lead to heavy snow across the Central Rockies. This upper-level feature is expected to 
track eastward through the beginning of the workweek along with its associated low pressure system. 
Ahead of this system's cold front, moisture should flow from the Gulf of Mexico into the 
Mississippi Valley and Southeast, leading to the potential for heavy rain beginning Sunday over the 
Mississippi Valley and into the Southeast by Monday and Tuesday. The Southeast has been anomalously 
wet over the past few weeks, so even modest rainfall totals could cause flooding issues in some 
areas.

Farther north and west, onshore flow into the Northwest on Sunday will cause precipitation in the 
Pacific Northwest and heavy snow in the Cascades and Northern Rockies. Then a shortwave trough 
diving south is expected to spin up a surface low in the Northern High Plains on Monday, and 
snowfall should continue on the backside of this low. That trough is forecast to develop southward 
through midweek and then move eastward, causing precipitation ahead of it. Models differ on the 
strength of the energy, so the depth and position of the surface lows in the guidance also differ, 
so the impacts are not easy to determine at this point in the forecast. For now, delineated a heavy 
snow area across parts of the Midwest eastward into the Upper Great Lakes for Tuesday into Thursday 
north of where the surface low may track, but uncertainty is fairly high.

As the aforementioned trough develops in the central U.S. and moves toward the eastern U.S., an 
arctic high will cause cold temperatures to develop. Minimum temperatures are forecast to be below 
average from the Rockies to Plains on Wednesday and into the Mississippi Valley on Thursday, but 
the maximum temperatures are forecast to be 15 to 20 degrees below average there Tuesday and 
Wednesday, spreading into the Ohio and Tennessee Valleys Thursday. 

Over Alaska, hazardous weather will be confined to the southern coastline and into the Panhandle. 
High winds are expected along the Aleutians and across the south-central coast as a potent low 
moves across during the early part of the week. Then precipitation will ramp up over the Panhandle 
and near the Gulf of Alaska coast for midweek as moisture increases.


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