Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
251 AM EST Sun Dec 03 2023

Valid 12Z Sun Dec 03 2023 - 12Z Tue Dec 05 2023

...A multi-day atmospheric river event will continue to impact the
Northwest and Rockies with heavy rain and significant mountain snowfall
Sunday and into Monday...

...Unsettled weather is forecast across the eastern third of the country
with rain along the East Coast & wintry weather from parts of the Midwest
and Great Lakes to northern New England...

...Generally milder than normal temperatures expected for across most of
the Lower 48...

A series of atmospheric rivers are forecast to produce heavy rainfall in
the Pacific Northwest into the upcoming week while heavy snow continues in
the Northern Rockies through Sunday. Unlike the past few days in the the
Pacific Northwest when heavy snow was the most impactful precipitation
type, the next storm system accompanying today's atmospheric river will
track farther north. This will stream milder air into western Oregon and
Washington, forcing rain to be the dominant precipitation type. Rain will
fall heavily at times in areas that now contains fresh snowpack, most
notably in western Oregon. This is a recipe for minor to moderate river
flooding, as well as flash flooding. WPC has issued a Slight Risk for the
Oregon Coast and the Cascade Range in both Oregon and southern Washington.
After a brief break between atmospheric rivers Sunday night, the next
atmospheric river arrives Monday with the heaviest rainfall likely to
occur in western Washington. WPC issued a pair of Slight Risks for the
Olympic Peninsula, northwest Oregon, and the Washington Cascades. Through
Monday night, portions of western Washington and Oregon can expect
anywhere from 3-7" of additional rainfall with locally higher amounts
possible. Farther inland, the higher terrain of central Idaho, the Tetons
in western Wyoming, the Wasatch in northern Utah, and the Colorado Rockies
have moderate-to-high chances (50-80%) of receiving greater than 12" of
snowfall. Most of the snowfall is expected to occur on Sunday with lighter
amounts in the northern Rockies on Monday.

Farther east, a storm system tracking through the eastern Great Lakes is
set to generate periods of rain and snow in the Great Lakes and as far
west as the Upper Mississippi Valley this morning. In addition, the Storm
Prediction Center has issued a Marginal Risk for severe weather in western
Pennsylvania today. In the Northeast, widespread showers are anticipated
from the Southeast on north along the Northeast's I-95 corridor. In
northern New England, temperatures will remain cold enough for
accumulating snow, particularly in the northern Appalachians. Snow will
pick up in intensity Sunday afternoon and persist into Monday morning from
northern New York and Vermont through central and northern Maine. Latest
WPC probabilities show a high chance (>70%) for snowfall totals >8" in the
White Mountains of northern New Hampshire and into central Maine. The
Winter Storm Severity Index (WSSI) depicts Moderate impacts in these
areas, while lighter amounts (>4" amounts) have a high chance (>70%) of
occurring in the higher elevations of the Adirondacks, the Green
Mountains, and into northern Maine. Minor Impacts are likely in those
areas according to the WSSI. Expect hazardous travel conditions in these
areas Sunday night and into the day on Monday. Light snow may stick around
into Monday night and early Tuesday across northern New England as the
storm slowly makes its way out to sea on Tuesday.

Elsewhere, a fast moving disturbance tracking southeast through the Upper
Midwest may bring light rain and snow to portions of the region Monday
night and into Tuesday. Temperature-wise, most of the continental U.S.
remains devoid of frigid or winter-like air-masses. Much of the Southeast
and coastal Mid-Atlantic are likely to wake up to record breaking mild
minimum temperatures today. The same is also be possible in the Pacific
Northwest Monday and Tuesday mornings. Temperatures will continue to warm
up in the West by Tuesday, but colder temperatures look to make a return
in the East by mid-week.

Mullinax

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