US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
335 PM EST Tue Nov 10 2020
 
Valid Friday November 13 2020 - Tuesday November 17 2020
 
Hazards:
- Heavy precipitation across portions of California, the Central Great Basin, the Pacific 
Northwest, and the Northern Great Basin, Fri-Tue, Nov 13-Nov 17.
- Heavy rain across portions of the Southeast, the Mid-Atlantic, and the Southern Appalachians, 
Fri-Sat, Nov 13-Nov 14.
- Heavy snow across portions of the Central Plains, the Central Great Basin, the Northern Plains, 
the Northern Rockies, the Central Rockies, and the Northern Great Basin, Fri-Sat, Nov 13-Nov 14.
- Heavy snow across portions of the Northern Rockies and the Northern Great Basin, Fri-Tue, Nov 
13-Nov 17.
- High winds across portions of the Pacific Northwest and the Northern Great Basin, Fri-Sat, Nov 
13-Nov 14.
- High winds across portions of the Central Rockies, the Central Plains, the Northern Plains, and 
the Northern Rockies, Sat, Nov 14.
 
Detailed Summary:

The focus for potential hazards in the medium range is on the remnants of Eta and an active stretch 
of weather in the Northwest. Starting with Eta, the forecast as of this afternoon is for the storm 
to be located in the northeast Gulf of Mexico on Friday while continuing to gradually weaken into 
the weekend. While the storm looks to weaken, its tropical moisture source becomes funneled north 
into the Southeast where upslope flow could lead to heavier rainfall rates over the southern 
Appalachians. It is also possible heavy showers could transpire as far east as the Carolina Coast 
and north towards the DelMarVa, but the overly saturated southern Appalachians are most at risk for 
heavy rainfall at this time. Some of this moisture may become caught by another storm system 
tracking through the Great Lakes and into southeast Canada Sunday night. This may lead to some 
light snow/ice accumulations in the higher elevations on northern New England, but totals currently 
look to be below heavy precipitation thresholds.

In the West, a powerful Pacific jet streak will be directed at the Pacific Northwest with a potent 
surface low slamming into coastal Washington or Vancouver Island late Friday. Exactly where the 
storm makes landfall can make all the difference in which areas receive significant impacts, most 
notably high winds. Wind gusts in excess of 55 mph are possible along the coasts of Washington and 
Oregon and might extend into the Willamette Valley. Should the storm make landfall in Vancouver 
Island, the core of strongest winds could move farther north and take place around the Puget Sound. 
Regardless, the setup does support the potential for a windstorm that may lead to power outages and 
downed trees. The high wind threat moves into the northern Rockies and areas in lee of these 
mountain ranges on Saturday. The more confident hazard of this forecast is for heavy precipitation 
up and down the coastal range from northern California to international border. Copious amounts of 
snow are likely to pile up in the Cascades and much of the northern Rockies. In wake of the storm 
system to start the period, a second storm system takes aim at the Pacific Northwest early-mid 
week. This keeps a persistent and healthy stream of Pacific moisture oriented at the region, and 
thus allows the threat for heavy mountain snow and valley/coastal rainfall to linger into the 
middle of next week.

Over Alaska, a Gulf of Alaska low should lead to an unsettled weather pattern in the lower 
Panhandle but precipitation amounts remain below hazardous thresholds. An amplifying ridge over the 
Bering Sea Sunday causes an injection of below normal temperatures into central and east-central 
Alaska. Temperatures are quite cold, but do not appear to be anomalously cold enough to warrant a 
"much below normal temperature" area at this time.

Mullinax