Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
332 AM EST Thu Feb 02 2023

Valid 12Z Thu Feb 02 2023 - 12Z Sun Feb 05 2023

...Ice Storm Winds Down Today Across Texas and Mid-South...

...West-Central Texas through the Mid-South...
Day 1...

Continued broad southwest to southerly flow above a dome of
residual cold air (sfc temps < 32F) in place across Texas and
portions of the Mid-South will continue the ice accumulation
threat through early afternoon today, all ahead of a shortwave
trough beginning to push into western Texas per recent water vapor
imagery and 500 mb heights. Through 18Z today, additional ice
accumulations will range from a few hundredths across central
Texas to locally 0.10" across portions of Arkansas. By afternoon
surface temperatures are expected to warm slightly above freezing
and the better moisture transport will transition eastward toward
the Southeast region, bringing a gradual end to the winter/ice
storm. For this morning, the WPC ice probabilities still show
moderate to high probabilities for at least 0.01" but tapers off
to just 10 percent or less for 0.10" across parts of Arkansas.


...Great Lakes...
Day 1-3...

An anomalously deep upper low rotating over Hudson Bay will drive
a fast moving Arctic front through the Great Lakes and Northeast
today through tonight, bringing a brief but intense shot of cold
air to the region where 850 mb temperatures are forecast to be
near -4 sigma below normal by early Saturday morning. Along the
frontal passage, broad area of light snow is expected with some
potential for embedded stronger snow showers or snow squalls,
though the timing of the frontal passage (nighttime) helping to
limit the low level lapse rates will dampen the snow squall
potential some. The cold airmass and favorable flow will bring
modest lake effect snowfall to the favored downwind areas. The
latest WPC probabilities are high (80%+) for 4"+ across portions
of the eastern U.P. of Michigan and upper L.P. as well as across
the Tug Hill through Friday evening. A quick moving Clipper will
skirt the Upper Midwest and Great Lakes late Friday into Saturday
bringing another round of light snow with an additional few inches
of light fluffy snow likely across portions of the U.P. of
Michigan.


...Northwest...
Days 2-3...

A shortwave trough will approach the West Coast early Friday
morning bringing a broad area of precipitation to the region.
Relatively warmer air and higher snow levels will limit snowfall
accumulations to the higher peaks of the northern California
mountains but heavy snowfall is likely for the northern WA
Cascades and Olympics through early Saturday where WPC
probabilities for 6"+ are high. After a quick reprieve, another
shortwave trough approaches California Saturday night into Sunday,
with this round likely to bring heavy snowfall to the higher peaks
of the Sierra Nevada where  WPC probabilities for a foot or more
of snow are already approaching 30% for the Day 3 period ending
12Z Sunday.


Taylor