FOUS11 KWBC 040749
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
249 AM EST Wed Mar 4 2026

Valid 12Z Wed Mar 04 2026 - 12Z Sat Mar 07 2026

...Northeast... Day 2...

A potent mid-level shortwave (currently over the Rockies) will
eject east-northeast out of the Midwest and weaken as it rides the
quasi-zonal flow into the Northeast. A trailing axis of confluence
over Atlantic Canada with a strong 1038+ mb surface ridge migrating
east out of Central Canada will set the stage for a mixed ptype
event as cold air remains entrenched over areas along and north of
I-90. Cold air damming, aided by a cold front from the Great Lakes
to Nova Scotia, will favor freezing rain as the precipitation mode
though some light snow is possible over New Hampshire into
southwestern Maine, which will be fully into the colder airmass.
Precipitation starting Thursday evening will continue through
Friday as the shortwave and associated weak area of surface low
pressure races eastward into the Atlantic. WPC probabilities for
at least 0.10 inch icing are moderate (40-70%) over the southern
Green Mountains and Berkshires as well as across southern New
Hampshire (Monadnocks) into the Worcester Hills. Probabilities for
at least 0.25 inch icing is highest (20-40%) over the southern
Greens and Berkshires. Lighter icing (>0.01" is probable for much
of the Adirondacks and Catskills across Vermont and New Hampshire
into northern CT/RI.

...Pacific Northwest, Great Basin, and Rockies... Days 1-3...

A mature system in the Gulf of Alaska weakening early this morning
will shunt a southern mid- level trough into the Pac NW today,
carrying a potent cold front ashore. A surge of modest moisture
and IVT, coupled with snow levels initially around 5000-6000ft,
will limit impacts. However, post- FROPA, snow levels will fall to
around 4000ft today then to near 3000ft Thursday as precipitation
becomes much lighter. Snow will spread eastward to the Northern
Rockies (northern ID to northwestern MT) early this morning then
to the Great Basin late this afternoon into Thursday as the upper
trough moves into southwestern OR. Snow could be heavy at times
near/above pass level as snow levels fall across the Cascades
today and then again tomorrow evening as the upper trough moves
through WA/OR. On Thursday, the trough will dig into Utah which
will enhance snowfall into the Uintas, WY ranges, and into the CO
Rockies, favoring upslope regions with ranges oriented
perpendicular to the northwesterly flow. Snow levels will continue
to fall across the region, initially around 7000ft in WY/CO late
Thursday but dropping to below 5000ft early Friday. This may
bring some lighter snow to areas east of the Front Range and High
Plains, including from eastern CO and southeast WY to western NE
and central SD.

WPC days 1-2 probabilities for at least 8 inches of snow are >50%
over the WA/OR Cascades, generally above 4000-5000ft. Plowable snow
(at least a few inches) is likely (>95% chance) around Snoqualmie
Pass. To the east, WPC probabilities through day 3 for at least 8
inches of snow are >50% above 5000-6000ft or so over the Blue
Mountains, central ID ranges, western/southwestern MT, northern NV
ranges, Uintas/Wasatch, and into the Wind River, Laramie, Park
Range, and Medicine Bow ranges. Maximum snowfall amounts of 1 to 2
feet can be expected in the highest peaks of these mountain ranges.

...Central/Northern Plains and Upper Midwest... Day 3...

More uncertainty regarding QPF and ptype exists throughout
the central/northern Plains and Upper Midwest on day 3 (12z Fri.
to 12z Sat.) as this system ejects eastward. Although less likely
at the moment, should a stronger shortwave eject northeastward
across the Plains on Friday and spawn a deeper surface low along
the advancing cold front, a band of heavy snow is possible.
However, the GFS remains alone in this higher end scenario.
Current WPC probabilities for at least 2 inches of snow are low
(20-40%) from western NE to northern MN.

Snell/Fracasso

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