US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
518 PM EST Tue Feb 09 2021
 
Valid Friday February 12 2021 - Tuesday February 16 2021
 
Hazards:
- Heavy precipitation across portions of the Lower Mississippi Valley, the Central Appalachians, 
the Tennessee Valley, the Mid-Atlantic, the Southern Appalachians, the Southeast, the Southern 
Plains, and the Ohio Valley, Tue, Feb 16.
- Heavy rain across portions of the Southeast, the Mid-Atlantic, and the Northeast, Tue, Feb 16.
- Heavy rain across portions of the Southeast, Mon, Feb 15.
- Heavy snow across portions of California, the Pacific Northwest, and the Northern Great Basin, 
Fri-Sat, Feb 12-Feb 13 and Mon, Feb 15.
- Heavy snow across portions of the Central Great Basin, California, and the Southwest, Sat, Feb 13.
- Heavy snow across portions of the Central Plains, the Central Rockies, the Central Great Basin, 
the Northern Rockies, the Southern Rockies, the Northern Great Basin, and the Southwest, Fri, Feb 
12.
- Heavy snow across portions of the Middle Mississippi Valley, the Lower Mississippi Valley, and 
the Southern Plains, Mon, Feb 15.
- Heavy snow across portions of the Great Lakes, the Mid-Atlantic, the Northeast, and the Central 
Appalachians, Sat-Sun, Feb 13-Feb 14.
- Much below normal temperatures across portions of the Pacific Northwest, the Northern Rockies, 
and the Northern Great Basin, Fri-Sun, Feb 12-Feb 14.
- Much below normal temperatures across portions of the Plains, the Mississippi Valley, the 
Central/Southern Appalachians, the Tennessee Valley, the Great Lakes, the Northern/Central Rockies, 
the Southeast, and the Ohio Valley, Fri-Tue, Feb 12-Feb 16.
- Much below normal temperatures across portions of the Northeast, the Central/Southern 
Appalachians, the Tennessee Valley, the Mid-Atlantic, the Southeast, the Great Lakes, and the Ohio 
Valley, Mon-Tue, Feb 15-Feb 16.
 
Detailed Summary:

Cold temperatures will be the predominant story for the upcoming Day 3-7 period (Friday, Feb 12 to 
Tuesday, Feb 16). An area of cold high pressure builds south out of Western Canada into the 
Northern Plains and the Central Plains by Sunday.  The high will move into the Upper/Middle 
Mississippi Valley by Monday, then into Northern New England by Tuesday.  The deeply entrenched 
arctic air mass brings widespread below to much below normal temperatures to many sections of the 
lower 48. The most significant impacts will be over the Central U.S., where temperatures will range 
from 20-45 degrees below normal through most of the period; this translates to an extended period 
of temperatures remaining below zero over the Northern Plains and sections of the Northern 
Intermountain Region. Sub-zero low temperatures will extend as far south as parts of Kansas and 
eastward into Wisconsin/Illinois through Sunday, with single digits reaching the Southern Plains 
and Northeast. Any winds will exacerbate the very cold air mass, leading to dangerously low wind 
chills for much of this area.

 Upper-level energy will help produce areas of heavy snow over parts of the Cascades on Friday and 
Saturday.  Heavy snow will develop over parts of the Central Rockies on Friday into Sunday.  The 
energy will also produce heavy snow over parts of the Northern Rockies on Friday and parts of the 
Sierra-Nevada Mountains on Saturday.  

Another area of upper-level energy will help produce an area of heavy snow over parts of the 
Northeast on Saturday and Sunday.  Heavy rain will develop along a front over the Florida Peninsula 
on Monday, and heavy rain will also develop along the Mid-Atlantic Coast on Tuesday.

A challenging aspect of this forecast is the precipitation type from the Western Gulf Coast 
northeastward into the Lower Mississippi and Tennessee Valleys into the Central Appalachians into 
the Mid-Atlantic on Tuesday.  The current guidance suggests the potential for accumulating freezing 
rain over Mid-Atlantic/Central Appalachians section into the Western Gulf Coast as the arctic air 
mass undercuts warmer temperatures aloft. There is still a lot of uncertainty with the details at 
this time.  With that uncertainty, WPC decided to depict the area as heavy precipitation for the 
time being.

Across Alaska, multiple areas of deep low pressure will develop near the Aleutians on Friday into 
Tuesday.  A plume of moisture will not make it as far as the Aleutians during the period.  However, 
we will keep an eye out to see if conditions will change over the next few days to depict a hazard 
over Alaska.  

Ziegenfelder