US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
258 PM EST Fri Nov 27 2020
 
Valid Monday November 30 2020 - Friday December 04 2020
 
Hazards:
- Heavy precipitation across portions of the Southern/Central Appalachians, the Tennessee Valley, 
the Ohio Valley, the Great Lakes, the Southeast, the Mid-Atlantic, and the Northeast, Mon-Tue, Nov 
30-Dec 1.
- Heavy snow across portions of the Great Lakes and the Ohio Valley, Mon-Tue, Nov 30-Dec 1.
- Heavy rain across portions of the Southern Plains, the Lower Mississippi Valley, and the 
Southeast, Wed-Fri, Dec 2-Dec 4.
- Heavy rain across portions of the Central Appalachians, the Mid-Atlantic, and the Northeast, 
Mon-Tue, Nov 30-Dec 1.
- Flooding occurring or imminent across portions of the Southeast.
- High winds across portions of the Northeast, Mon, Nov 30.
- Much below normal temperatures across portions of the Southern Plains, the Lower/Middle 
Mississippi Valley, the Tennessee Valley, the Southern Appalachians, and the Southeast, Tue-Wed, 
Dec 1-Dec 2.
- Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Mon-Fri, Nov 
30-Dec 4.
- High winds across portions of mainland Alaska and the Aleutians, Mon, Nov 30.
- High winds across portions of the Alaska Panhandle and mainland Alaska, Mon-Tue, Nov 30-Dec 1.
 
Detailed Summary:

Over the medium range hazards time period (Monday, Nov 30 - Friday, Dec 4), upper-level and surface 
low pressure systems are forecast to track across parts of the eastern U.S. until midweek, while 
renewed upper-level troughing should drop through the Northwest Monday/Tuesday and into the central 
U.S. for the second half of the week. First, the deep upper-level trough/low is forecast to move 
through the Ohio Valley and Great Lakes region, while surface frontal systems move across the East. 
Ahead of the cold fronts, warmer than normal temperatures and heavy rain and thunderstorms are 
likely across the Mid-Atlantic and Northeast on Monday and lingering in New England Tuesday. 
Blustery conditions could also lead to high wind gusts especially in coastal and mountainous areas 
of the Northeast on Monday. Any enhanced rain amounts could cause flooding/flash flooding issues, 
and the potential for strong thunderstorms will continue to be monitored as well. Farther west on 
the backside of the low and behind the cold fronts, precipitation is likely to transition to snow 
for portions of the Great Lakes, Ohio Valley, and higher elevations of the Appalachians Monday and 
Tuesday, with light snow potentially lingering in the Great Lakes on Wednesday. Uncertainty remains 
regarding placement and amounts of the snow as it wraps around the low, but those still appear to 
be the most likely areas to see notable snow. Gusty winds are also possible for the Great Lakes 
underneath the upper low.

The next upper-level trough/low is forecast to drop southward across the Northwest early in the 
week, causing only light to modest precipitation there given limited moisture. Then as the upper 
low takes hold in the central U.S., a surface low is expected to move through the Gulf Coast 
states. As Gulf of Mexico moisture flows into the low's vicinity, heavy rainfall potential could be 
renewed across the Gulf Coast states from Wednesday onward. The area of rain should generally move 
west to east with the surface low, but with increasing uncertainty on position and amounts of 
rainfall late in the week.

Cooler than average temperatures will prevail from the Central/Southern Plains toward the 
Middle/Lower Mississippi, Tennessee, and Ohio Valleys toward the Southeast through the period 
underneath the lower than normal upper-level heights. Low temperatures on Tuesday and Wednesday 
mornings could be particularly cold over portions of the Lower Mississippi Valley and Southeast, 
and a Much Below Normal Temperatures hazard area was drawn where places could experience their 
first freeze or hard freeze of the season. Periods of above average temperatures are forecast for 
portions of the northern tier. 

Alaska is also likely to see an active medium range period. A quite deep surface low is forecast to 
track through the Gulf of Alaska south of the Aleutians (possibly causing high winds there) Monday, 
continuing eastward Tuesday and moving into Southcentral by Wednesday. A deep plume of persistent 
Pacific moisture (atmospheric river) is likely to take aim at the Southcentral coast and Panhandle 
ahead of the cold front associated with the low, causing heavy precipitation totals over those 
areas. The highest precipitation amounts are likely on Tuesday, but surrounding days will be wet as 
well. Strong winds are also a threat, and some notably high wave heights are possible in the Gulf. 
Temperatures are expected to warm throughout the week, with the exception of the Aleutians and 
Alaska peninsula.

Tate