FOUS11 KWBC 060901
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
401 AM EST Thu Mar 6 2025

Valid 12Z Thu Mar 06 2025 - 12Z Sun Mar 09 2025

...Great Lakes and Maine...
Days 1-2...

Primary surface low near the northern Ontario/Quebec border will
continue to drift northeast through today. The negatively tilted
upper trough south of this low will shift up the Mid-Atlantic coast
today with rapid surface cyclogenesis tonight over the Gulf of
Maine. LES on northeasterly flow develops tonight over the eastern
U.P. and over Upstate NY (particularly near Syracuse) where Day
1.5 snow probs for >4" are 40-60%. Wrap around snow lifts over
eastern/northern Maine late tonight/Friday morning with Day 1.5
snow probs for >4" are 40-60% over northern Maine.


...Southwest, Central Rockies across the Central Plains into the
Midwest, then Southern Rockies, and Southern Plains...
Days 1-2...

...Heavy snow bands today into Friday from Wyoming across northern
Nebraska into northern Iowa...

Mid-level low along the far northern CA coast will shift south to
southern CA through tonight before further developing over the Four
Corners Friday night and shifting east to the TX Panhandle Saturday.
Meanwhile, the leading base of the trough currently over SoCal
will eject northeast over the southern Rockies by this afternoon,
across the central Plains tonight before weakening as it approaches
Chicago Friday.

Strengthening SWly jet ahead of the leading trough will allow for
quick ejection and rapid lee-side cyclogenesis over eastern CO/KS
this afternoon through tonight. Rapid banding of precip north of
this low will spread north over much of WY this morning, then shift
east over northern Neb tonight, persisting, but in a weakened state
over IA Friday. Snow totals have increased through this swath with
Day 1 snow probs for >8" over 80% in central WY terrain and 40-70%
over northern Neb. Ample Pacific moisture ahead of this wave will
keep snow levels over the Great Basin and Four Corners 4000-7000 ft
today, but will fall under the upper trough to 3000-4000ft. Day 1
WPC probabilities are high (>70%) for >8" across the terrain of
eastern NV, the Wasatch, Uintas, Wind Rivers, western CO ranges and
the highest terrain along the Mogollon Rim. Day 1 snow probs are
also high for >6" in the SoCal peninsular ranges.

SW of this secondary low, the pivoting upper low moving across the
Four Corners will drive another area of pronounced ascent leading
to periods of moderate to heavy snow across the Desert Southwest
and extending east through the TX/OK Panhandles. The column across
this region is modestly cold enough to support snow, with snow
levels around 5000-7000 ft, but steep lapse rates aloft beneath
the low will help cause strong lift to dynamically cool the
column. This suggests a mixture of rain and snow, becoming all snow
near the surface at times of heavier precipitation rates and in
terrain. Day 2.5 WPC for >6" are 40-80% over the southern Sangre
De Cristos with >4" probs 20-60% east of terrain such as the Raton
Mesa.


Jackson



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