US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
307 PM EST Tue Dec 10 2019
 
Valid Friday December 13 2019 - Tuesday December 17 2019
 
Hazards:
- Heavy precipitation across portions of the Northeast, the Central Appalachians, the Tennessee 
Valley, the Mid-Atlantic, the Southern Appalachians, the Great Lakes, and the Ohio Valley, Mon-Tue, 
Dec 16-Dec 17.
- Heavy precipitation across portions of the Northeast and the Great Lakes, Sat-Sun, Dec 14-Dec 15.
- Heavy rain across portions of the Lower Mississippi Valley, the Tennessee Valley, the 
Mid-Atlantic, the Southern Appalachians, the Southeast, the Southern Plains, and the Ohio Valley, 
Sun-Tue, Dec 15-Dec 17.
- Heavy rain across portions of the Northeast, the Central Appalachians, the Tennessee Valley, the 
Mid-Atlantic, the Southern Appalachians, the Southeast, and the Ohio Valley, Fri-Sat, Dec 13-Dec 14.
- Heavy snow across portions of the Central Rockies, the Northern Plains, the Northern Rockies, and 
the Northern Great Basin, Fri, Dec 13.
- Heavy snow across portions of the Central Great Basin, Fri-Sat, Dec 13-Dec 14.
- Heavy snow across portions of the Central Rockies, the Central Plains, and the Central Great 
Basin, Fri-Sun, Dec 13-Dec 15.
- Flooding possible across portions of the Northern Plains.
- Flooding occurring or imminent across portions of the Northern Plains.
- High winds across portions of the Northeast, Sat, Dec 14.
 
Detailed Summary:

In the eastern U.S., two main systems could cause hazardous weather for the weekend into early next 
week. First, precipitation is expected to spread along the Eastern Seaboard on Friday into Saturday 
as moisture flows in ahead of an upper-level trough and as a surface low pressure system takes 
shape in the Gulf of Mexico Friday and lifts as a nor'easter. Most of this is expected to fall as 
rain (potentialy heavy) under a warm pattern, but there is some chance of snow on the backside of 
the low from portions of the Mid-Atlantic to the interior Northeast by Saturday. Additionally, the 
surface low could be sufficiently strong enough to cause high winds along the New England Coast 
Saturday.

Another upper-level trough is forecast to move eastward from the Plains on Monday toward the 
Mississippi and Ohio Valleys Tuesday, with a round of precipitation ahead of it. Heavy rain should 
begin in the Lower Mississippi Valley late Sunday into Monday, and precipitation will spread north 
and eastward from there into the Tennessee and Ohio Valleys and farther north by Tuesday. 
Precipitation on the northern and western side could fall as snow--for now, the best chances of 
snow through Monday night are for portions of the Ohio Valley into the Central Appalachians, and 
snow could spread into the Mid-Atlantic and Northeast on Tuesday. Freezing rain and mixed 
precipitation could also be threats in the transition zone between snow and rain. This potential 
for wintry weather will continue to be monitored as we get closer to the event.

In the western U.S., a strong jet stream will help bring Pacific moisture into the region in the 
short range and through Friday, leading to the possibility of heavy snow in higher elevations of 
the Rockies, Wasatch, and Tetons. Moisture should decrease by Saturday, but upslope flow could lead 
to some snow continuing into early next week in the Central Rockies.  

For Alaska, a series of low pressure systems could pass west to east across the Aleutians and 
southern Alaska coast, bringing precipitation to those areas, which could be locally heavy on 
Friday through Monday. Then the possibility exists for another low to track northward across the 
Panhandle by Monday and Tuesday, which could also cause locally heavy precipitation. Uncertainty in 
the placement of the heaviest rain and snow totals precluded drawing hazard areas on the Hazards 
chart for now. 

Tate