Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
237 AM EST Mon Dec 04 2023

Valid 12Z Mon Dec 04 2023 - 12Z Wed Dec 06 2023

...Excessive rainfall and instances of flooding are likely across parts of
western Washington and Oregon over the next few days...

...Moderate snowfall to diminish throughout northern New England today...

...Heavy upslope snow potential forecast across the central Appalachians
Tuesday night into Wednesday...

A strong atmospheric river is anticipated to soak the Pacific Northwest
today and continue the heavy rainfall potential through midweek. Main
impacts associated with this storm system are expected to include the
threat of flooding caused by heavy rainfall and snowmelt. A broad stream
of anomalous atmospheric moisture content extending from just north of
Hawaii is forecast to move inland into western Washington and Oregon by
tonight along a frontal boundary, which is also connected to a very strong
low pressure system entering the Gulf of Alaska. The subtropical
connection will lead to a very mild system with high snow levels. This
means much of the Cascades and coastal ranges will experience heavy rain
as opposed to heavy snow, exacerbating the potential flood threat due to
increased runoff. Flood Watches have been issued for much of western
Washington and Oregon, where most areas could see 2-3"+ rainfall amounts
by Wednesday. Moderate rainfall may also extend east of the Cascades and
into northern Idaho. Residents are advised to never drive through flooded
roadways and have an action plan to protect property if within a flood
zone.

Outside of the Northwest, mostly light precipitation is forecast
throughout the rest of the country by midweek. The ongoing snowstorm
impacting northern New England is forecast to slowly subside today. A few
additional inches of snowfall are expected across northern Vermont and New
Hampshire, as well as much of Maine, which could lead to treacherous
travel early this morning. The next system spreading snowfall potential
into parts of the U.S. will be an Alberta Clipper diving from the Dakotas
today to off the North Carolina coast on Wednesday. Strong winds are
expected as the low pressure system moves across the northern Plains
today, which has prompted High Wind Warnings and Wind Advisories for parts
of Montana, Wyoming, and the Dakotas. Scattered snow showers will also
accompany this system until feeding the upslope snow potential across the
central Appalachians beginning Tuesday night. Subfreezing temperatures
along the Allegheny Front and increased moisture due to northwesterly flow
into the terrain will allow for potentially heavy snow. WPC probabilities
for at least 4" of snow reach to around 40-60% in the higher terrain of
West Virginia on Wednesday.


Snell


Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php