Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
247 AM EST Fri Dec 01 2023

Valid 12Z Fri Dec 01 2023 - 12Z Sun Dec 03 2023

...Multi-day winter storm will impact travel in the Northwest with
significant mountain snow and heavy rain...

...Unsettled weather forecast across the eastern third of the country with
heavy rain potential along the Gulf Coast and Southeast, while wintry
weather is expected from parts of the Midwest and Great Lakes to northern
New England...

Meteorological winter is off to a fast start across much of the Northwest,
Great Basin, and Rockies as plentiful moisture streams inland from the
Pacific Ocean over at least the next few days. The specific region seeing
the most impacts from heavy mountain snow and heavy rain will be the
Pacific Northwest, where a strong atmospheric river is expected to wallop
the region on Sunday after continuous instances of moderate precipitation
today and Saturday. Total rainfall amounts through this weekend are
expected to approach 5 to 10 inches along the coastal ranges of western
Washington and Oregon, with several inches of rain also expected for
places such as Portland, OR and Seattle, WA. Heavy snow likely adding up
to at least a few feet is expected across the Cascades, including many
mountain passes. Travel will be difficult to hazardous due to both heavy
snow and blowing snow. Snow levels are expected to increase by Saturday
night and throughout the day on Sunday, leading to heavy rain on top of
recent snowfall throughout the Cascades. This combination of heavy rain
and snowmelt on Sunday will likely produce minor to moderate river
flooding.

Heavy snow potential will also extend into the mountainous terrain of the
Great Basin and Rockies as leftover moisture transport continues to slide
eastward from the Pacific. Heavy snow is likely to reach into several
mountain ranges from Idaho and Montana to Colorado. The highest peaks are
forecast see as much as 1 to 3 feet of snow. Winter Storm Warnings and
Winter Weather Advisories have been issued for areas most likely to see
impactful and/or hazardous snowfall.

An increasing southwesterly jet stream over the eastern U.S. will allow
for unsettled and mild weather to overspread the region during the first
weekend of December. An initial system is forecast to progress from the
Midwest to the Great Lakes by Saturday as another developing system right
on its heels enters the Great Lakes on Sunday. Overall, light rain is
expected across the Ohio Valley, Appalachians, Northeast, and
Mid-Atlantic. However, elevated atmospheric moisture content and
instability may lead to locally heavy rainfall and thunderstorms along the
Gulf Coast today. This threat of heavy rainfall then pushes farther north
into the Southeast on Saturday ahead of a central U.S. upper trough.
Farther north, wintry weather is expected on the northern periphery of the
precipitation shield as cold air remains in place due to a stretched out
high pressure system extending into southeast Canada. Mostly light and
localized snowfall is expected from parts of eastern Iowa to the Lower
Peninsula of Michigan through tonight. Heavier snow is possible across
northern New England on Monday, where modest probabilities (40-60%) for
greater than 4 inches of snow exist between northern New Hampshire and
northern Maine.

Elsewhere, mostly dry conditions are expected across the central and
southwestern United States. Below average temperatures are also
anticipated to be confined to the central Plains and West through the
beginning of the weekend, with above average temperatures throughout the
remainder of the CONUS.

Snell

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