US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
205 PM EST Fri Dec 04 2020
 
Valid Monday December 07 2020 - Friday December 11 2020
 
Hazards:
- Heavy precipitation across portions of the Pacific Northwest, Tue, Dec 8.
- Flooding possible across portions of the Southern Appalachians, the Mid-Atlantic, the Northeast, 
and the Central Appalachians.
- High significant wave heights for coastal portions of the Pacific Northwest, Mon, Dec 7.
- Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Mon-Tue, Dec 
7-Dec 8.
- High significant wave heights for coastal portions of the Alaska Panhandle and mainland Alaska, 
Mon, Dec 7.
 
Detailed Summary:

It looks like much of the lower 48 will experience relatively dry weather for much of next week. 
The only really notable exception will be the Pacific Northwest, where a cold front and associated 
onshore flow will support some moderate to isolated heavy precipitation (upwards of 1-2 inches) 
across the Olympics and northern Washington Cascades later Monday into Tuesday. This is a warm 
system for early December, so snow levels will range higher than average for this event. In 
addition, a long fetch of southwesterly flow associated with a powerful low tracking south of the 
Aleutians will support waves up to 20 feet offshore of western Washington during Monday, then 
diminishing by Tuesday.

Otherwise, there's the potential for Santa Ana winds in central/southern California early next week 
as an upper level low tracks south-southwest from the Great Basin through southern California. At 
this time, this doesn't appear to be a significant event (unlike the conditions earlier this week), 
so opted not to outline a hazards area. Farther east, upper level ridging and downslope flow will 
result in an unusually mild stretch of days across the Plains and upper Midwest. High temperatures 
Monday-Wednesday will range up to 15-25 degrees above normal before cooler weather returns later 
next week.

Over Alaska, onshore flow associated with a large and deep area of low pressure tracking into the 
Gulf of Alaska will bring widespread moderate to heavy precipitation Monday into Tuesday into 
south-central Alaska (mostly east of the Kenai Peninsula) and across much of the Alaska Panhandle. 
Precipitation amounts will range up to 1-3 inches each day over south-central Alaska, but likely 
somewhat lighter over the Panhandle. However, given the recent very heavy rainfall, any additional 
amounts could exacerbate flooding. In addition, as mentioned above, a large area of significant 
wave heights of around 20-25 feet are expected Monday across coastal sections of the same general 
region impacted with heavy precipitation. Elsewhere, there are indications of a potentially strong 
low developing and tracking near or across the western Aleutians toward the latter part of next 
week. There are still notable discrepancies among the models, but it's something to monitor over 
then next few days.

Klein