FOUS11 KWBC 210929
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
429 AM EST Sat Feb 21 2026

Valid 12Z Sat Feb 21 2026 - 12Z Tue Feb 24 2026

...Central Appalachians, Mid-Atlantic, Northeast...  Days 2/3...

*** Nor'easter develops near the Mid-Atlantic Coast Sunday with
 heavy snow and blizzard conditions for at least coastal areas
 spreading across the Northeast through Monday ***

Northern stream trough currently over north-central MT shifts
southeast across the Great Plains today before closing into a mid-
level low over the Midwest tonight into Sunday. This low the
translates to a coastal surface low Sunday first near Cape Hatteras
then up along the Mid-Atlantic seaboard Sunday night when rapid
intensification is expected. The low tracks northeast over the
70W/40N benchmark Monday before tracking near Nova Scotia Monday
night. with appreciable impacts poised for a large portion of the 
Mid-Atlantic and Northeast. 

Model consensus is still lacking with the track off the Mid-
Atlantic/Northeast with the 00Z GFS still on the west side and
stronger. The 00Z AIGFS and ECAIFS are just east, then it's the 00Z
ECMWF. These track differences account for notable spread in
precip/snow solutions. That said, confidence continues to increase
for major impacts to at least the Mid-Atlantic coast and southern
New England. Powerful winds should create blizzard conditions at
least for the coastal areas with blowing snow concerns farther
inland as well. The western extend of the precip shield (how far
inland the heavy snow extends) remains to be seen. The initial wave
of precip will spread across the Mid-Atlantic early Sunday with
marginal surface temperatures noted. The TROWAL and translating 
energy development look to be dynamic enough for snow in the higher
precip rates during the day Sunday before increased cold makes for
more widespread heavy snow Sunday night for the Mid-Atlantic and
southern New England coasts. Day 2 snow probs for >6" are over 40%
from northern and eastern Virginia through southern New England
with 40-70% probs for >12" for the eastern shore of MD through NJ,  
NYC, and Long Island. The Day 2.5 snow probs for >12" are 40-80%
the over RI and eastern Mass. The track for Monday is then toward
Nova Scotia with outer portions of the precip shield along the
Maine coast with ocean enhanced snow continuing for southeast Mass.
The 40% line for Day 3 snow probs >8" is essentially along the Maine coast.

Powerful winds accompany this rapid intensification with mixing
possible up to around 850mb. Blizzard conditions likely along the 
northern Mid- Atlantic Coast, Long Island, and southeast Mass. Low 
snow ratios can be expected along the coast with marginal surface 
temperatures and damaging winds. Key Messages are linked below.

Synoptic snow overspreads the central Appalachians on westerly 
flow late tonight through Sunday before flow shifts to NW as the 
coastal low rapidly develops Sunday night. This upslope flow of 
Great Lakes moisture laden air brings snow bands/showers Sunday 
night through Monday. Storm total snow looks to be 6-12" for the 
Allegheny through Laurel Highlands. 

...Cascades and Far Northern Rockies... Days 1-3...

Deep low shifts south well off the BC coast today before stalling
well off the WA coast tonight through Monday. The first round of
coastal to Cascades precip is today with decent precip rates
increasing to 3000-4000ft feet. Day 1 snow probs for >6" are 50-80%
mainly in the WA Cascades and the Trinity Alps of CA. 

There is a bit of a lull in onshore flow tonight before the next
wave arrives along the Cascades Sunday. Snow levels rise to
4000-5000ft Sunday with Day 2 snow probs for >6" again 50-80% in
the WA Cascades and the Trinity Alps/Mt Shasta. 

The third wave of precip lingers over WA Sunday night before
shifting south down the PacNW coast and inland over the northwest
MT ranges Monday. Snow levels rise to 4000-6000ft in WA/OR and MT
while they rise to 8000ft in northern CA. Day 3 snow probs for >6"
are 50-90% in the WA Cascades and over the far NW MT ranges. 

...Great Lakes... Days 1/2...

An inverted trough lingers over northern Michigan through tonight.
Persistent low-level convergence along this inverted trough 
combined with steepened lapse rates aloft beneath a broad mid-level
trough will promote continued favorable ascent for a narrow 
corridor of heavy snowfall with max snowfall rates above 1"/hr. 
A narrow axis will continue to be focused across the U.P. with Day
1 WPC probabilities for >6" 40-60% across the Keweenaw Peninsula 
and the Huron Mountains, and the central U.P. shore.

This trough weakens Sunday, but a mid-level trough digs over the
Great Lakes, with NNWly flow and CAA increasing over Lakes Superior
and Michigan. Day 2 snow probs for >4" are around 40% for the
Porcupine and Huron Mtns in the U.P. as well as far southwest MI
into northern IN.

Jackson

...Winter Storm Key Messages are in effect and linked below...

https://www.wpc.ncep.noaa.gov/key_messages/La...

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