Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
245 AM EST Thu Feb 22 2024

Valid 12Z Thu Feb 22 2024 - 12Z Sun Feb 25 2024

...Northern Mid-Atlantic and Northeast...
Days 1 and 2...

A surface low associated with a low-amplitude mid-level wave and
favorable upper jet forcing will move through the Ohio Valley
today.  Deep southwesterly flow ahead of the wave will support
ample moisture transport into the northern Mid-Atlantic and the
Northeast, fueling widespread precipitation across the region. 
However, marginal forcing across the region is expected to keep
amounts light for most locations.  Thermal profiles continue to
suggest a wintry mix, with areas of freezing rain as far south as
the Laurel Highlands in southwestern Pennsylvania.  Spotty areas
of freezing rain are possible further northeast across the higher
elevations of northern Pennsylvania, central and eastern Upstate
New York into New England, with mostly snow expected across
interior northern New England.  Snow and ice accumulations are
forecast to be light, with the probabilities for 0.10 inch ice and
four inch snow accumulations less than 10 percent for most areas.

In the wake of the initial wave, a more amplified wave is forecast
to through the Mid-Atlantic, with low pressure developing off of
the Northeast coast Friday night.  While uncertainty remains, the
majority of the guidance shows the low developing and tracking too
far offshore to present a significant snow threat for the
northeastern U.S.

...Pacific Northwest to the northern Rockies...
Day 3...

Following a period of dry weather extending from late in the week
into the early part of the weekend, onshore flow is expected to
return and strengthen ahead of an amplifying low over the Gulf of
Alaska.  Snow levels are expected to be between 3,000-3,5000 ft as
snow spreads south across the northern Cascades and Rockies on
Saturday, followed by a small increase as a shortwave ridge builds
ahead of the approaching low.  Precipitation through early Sunday
is forecast to remain mostly confined to western Washington,
northern Idaho, and northwestern Montana, with more widespread
heavy precipitation expected to unfold beyond the Day 3.  However,
some areas including the northern Cascade passes and Marias Pass
in northwestern Montana may begin to see impactful snow
accumulations by the end of the period.  

Pereira