US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
237 PM EST Wed Jan 20 2021
 
Valid Saturday January 23 2021 - Wednesday January 27 2021
 
Hazards:
- Heavy precipitation across portions of the Central Appalachians, the Mid-Atlantic, California, 
the Southern Appalachians, the Great Lakes, and the Ohio Valley, Mon-Tue, Jan 25-Jan 26.
- Heavy precipitation across portions of the Central Great Basin and California, Wed, Jan 27.
- Heavy rain across portions of the Lower Mississippi Valley, the Central Appalachians, the 
Tennessee Valley, the Middle Mississippi Valley, the Mid-Atlantic, the Southern Appalachians, the 
Southeast, the Southern Plains, and the Ohio Valley, Sun-Mon, Jan 24-Jan 25.
- Heavy snow across portions of California, the Pacific Northwest, and the Northern Great Basin, 
Sun, Jan 24.
- Heavy snow across portions of the Central Great Basin, California, and the Southwest, Sun-Mon, 
Jan 24-Jan 25.
- Heavy snow across portions of the Central Rockies, the Central Great Basin, the Northern Plains, 
the Southern Rockies, the Upper Mississippi Valley, and the Southwest, Sat-Sun, Jan 23-Jan 24.
- Heavy snow across portions of the Central Great Basin and the Southwest, Mon, Jan 25.
- Heavy snow across portions of the Southwest, Mon-Tue, Jan 25-Jan 26.
- High winds across portions of the Aleutians, Tue-Wed, Jan 26-Jan 27.
 
Detailed Summary:

The medium range period (Saturday, January 23 to Wednesday, January 27) will feature a fairly 
typical January weather pattern, with multiple areas of potentially impactful wintry precipitation. 
Starting with this upcoming weekend, a shortwave trough is expected to bring potentially heavy snow 
to the western Colorado mountains. Meanwhile, precipitation is also expected to break out on 
Saturday across the Upper Midwest from South Dakota to Wisconsin. Snowfall amounts should remain 
relatively light; however, snow totals could reach warning criteria across southern Minnesota and 
far northern Iowa. 

By the end of the weekend, additional upper-level energy is forecast to eject from the Southwest 
and into the south-central United States. This will help increase moisture transport from the 
eastern Pacific and western Gulf of Mexico. Combined with an approaching cold front, the expected 
atmospheric set up will allow for potentially heavy rain from far eastern sections of the Southern 
Plains, throughout much of the Tennessee and Ohio valleys, as well as into the southern 
Appalachians. There are high probabilities of greater than 1 inch of rain for these areas, with 
potential local amounts greater than 2 inches. On the northern periphery of the precipitation 
shield there is the potential for snow. This includes areas from the Midwest to Northeast. At the 
moment, confidence is highest across the northern Mid-Atlantic regarding impactful wintry 
precipitation between Monday and Tuesday. Cold air should remain in place long enough to support 
snow, sleet, and/or freezing rain from the central Appalachians to Pennsylvania. Further north, the 
northern edge of the precipitation shield will likely be sharp and snowfall amounts will drop off 
significantly. Be sure to check back for the latest forecast as the time period approaches. 

Much needed precipitation will continue to impact the Southwest and West Coast during the medium 
range forecast period thanks to a persistent upper-level trough. Heavy snow will be found from the 
Cascades to the Sierra Nevada between Sunday and Monday. Heavy precipitation will make it as far 
south as Southern California, with rain along the coast and snow across the Transverse and 
Peninsular ranges. Heavy snow is also be a concern Monday and Tuesday across the Mogollon Rim in 
Arizona, as well as higher elevations in Utah and Nevada. By Wednesday there is the potential for 
an atmospheric river across northern California. There is still considerable spread with the 
location and timing, as the axis of heavy rain could come after Wednesday. A highlighted area was 
added to today's hazard chart to increase awareness on the potential event.

Across Alaska, temperatures are forecast to remain well above average throughout southern and 
western portions of the state. By Tuesday and Wednesday, a potent low pressure system is expected 
to enter the Bering Sea and could produce high winds along the Aleutian Islands. 

Snell