Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
215 PM EST Thu Nov 25 2021

Valid 00Z Fri Nov 26 2021 - 00Z Sun Nov 28 2021

...Developing storm system to produce heavy snow and gusty winds across
portions of the Interior Northeast and Northern New England beginning
early on Friday...

...Atmospheric River to generate moderate-to-heavy rainfall in the Pacific
Northwest tonight and again on Saturday...

...Strong Santa Ana wind event to cause threatening fire weather
conditions and destructive wind gusts through the end of the week...

The primary weather maker this Thanksgiving and succeeding Black Friday is
associated with an area of low pressure tracking through the Upper Great
Lakes. Its trailing cold front is causing numerous showers to develop from
the Great Lakes and Mid-South to the western Gulf Coast. In fact, South
Texas may experience a few thunderstorms capable of producing locally
heavy rain tonight. By Friday morning, showers are forecast to reach the
East Coast while colder temperatures funneling behind the cold front
initiate lake effect snow bands across parts of the eastern Great Lakes
and into the interior northern Mid-Atlantic. This storm system is set to
strengthen quickly during the day Friday as an upper level low deepens
over the Northeast. On the northern side of this upper low, periods of
snow are expected with the heaviest totals taking shape over northern New
England. Latest forecast totals show over six inches of snow in the
Adirondacks, with as much as a foot possible in the Green and White
Mountains. Travelers in northern New England may contend with icy and
treacherous conditions, especially on untreated surfaces late Friday into
Saturday morning. Gusty winds will also accompany the system, particularly
between Friday night and Saturday, which could lead to reduced visibility
due to blowing snow. Winter Storm Watches have been issued from northern
New York State to northern Maine.

In the West, a new Atmospheric River containing rich subtropical Pacific
moisture takes aim at the Pacific Northwest this evening. A prolonged
stretch of moderate-to-heavy rainfall combined with rapid snow melt could
lead to excess runoff. This may result in quickly rising creeks and
streams, making localized flooding a possibility in parts of western
Washington. Locally heavy rainfall is also possible in far northwestern
Oregon, but the heaviest rainfall totals (1 to 3 inches) are most likely
to occur in the Olympics and northern Cascades. High pressure building in
atop the Northwest on Friday will provide a brief break in the action, but
another round of heavy rain arrives late Saturday. This next Atmospheric
River event is expected to produce an additional 1 to 3 inches of rain
across the Olympics and northern Cascades beginning Saturday afternoon,
with locally higher amounts possible. Given the recent periods of heavy
rainfall, flooding and excessive runoff will undoubtedly be a concern once
again.

In contrast to their neighbors in the Northwest, residents in Southern
California are dealing with dry Santa Ana winds. High Wind Warnings have
been posted along the mountain ranges, as well as coastal regions.
Widespread wind gusts of 35 to 60 mph are expected with damaging gusts up
to 75 mph possible in the mountains and foothills. In addition,
dangerously low humidity levels support a hazardous environment for fire
weather conditions. Red Flag Warnings and a Critical Risk for hazardous
fire weather conditions, issued by the Storm Prediction Center, were
issued for much of the Southern California mountains and adjacent
foothills. The Santa Ana wind event this afternoon should wind down to an
extent by tonight, but an Elevated Risk for favorable fire weather
conditions looks to persist into Black Friday. Temperature-wise, a cold
front is set to usher in yet another shot of cold Canadian air on Friday
throughout the East. December-like temperatures look to stick around in
the Mid-Atlantic and New England on Saturday. Meanwhile, a building upper
level ridge over the western third of the Lower 48 means temperatures will
warm-up incrementally each day to close out the week and into the upcoming
weekend.

Snell

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