Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
246 AM EDT Fri Apr 11 2025

Valid 12Z Fri Apr 11 2025 - 12Z Mon Apr 14 2025


...Northern Mid-Atlantic to New England...
Days 1-2...

Ongoing light snow this morning will taper off just after 12Z, but
will then turn to the next area of wintry weather later tonight
into Saturday. Upper trough axis will slowly approach the East
Coast with front-side/downstream upper low development over the
Mid-Atlantic. This will favor another surge of moisture northward
into marginally cold air over the Northeast/northern Mid-Atlantic
as mostly snow to the north away from the coast (roughly south of
I-90/I-84) but perhaps a small area of sleet as well. Ptypes will
be dependent on rates where temperatures are marginal, with some
areas alternating between rain/snow. In addition, accumulation may
be limited to grassy areas given mild ground/road temperatures and
also may be limited within a few hours of solar noon as we approach
mid-April. However, some more vigorous WAA over higher terrain
could yield several inches of snow on Saturday for places like the
Catskills, Berkshires, and southern Green/White mountains where WPC
probabilities for at least 4 inches of snow are generally 20-50%.
The northern extent of the snow is still a bit in question as the
system tries to consolidate toward the Gulf of Maine Sunday before
moving out of the area.


...Cascades to Northern Rockies...
Day 1-3..

Broad SW flow this morning will continue light snow for the
Cascades today while the trough axis slowly approaches out of the
northeastern Pacific. By Saturday, a stronger mid-level shortwave
will come into WA and strengthen across ID/MT, promoting light to
modest WAA-driven snow over NW MT into northern WY as the upper jet
slips southeastward into the Plains. Temperatures will fall behind
the front and lower snow levels to below 4000ft as precipitation
lightens and then ends from west to east on Sunday/Sunday night.
The system will be fairly progressive but it could snow moderately
(>1"/hr) for a time Saturday evening. WPC probabilities for at
least 8 inches of snow for the period are highest around Glacier NP
and across the Little Belt Mountains (>50%).


The probability of at least 0.10" of freezing rain across CONUS is
less than 10%.


Fracasso