Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
248 PM EDT Sat Apr 12 2025

Valid 00Z Sun Apr 13 2025 - 00Z Wed Apr 16 2025


...Maine...
Day 1...

System that brought locally heavy snow to portions of the Northeast
and New England today is weakening, but the associated upper trough
off the East Coast will become reinvigorated tonight and throughout
the day on Sunday as additional shortwaves swing over the Mid-
Atlantic. This will allow for a few waves of precipitation to surge
northward into northern New England and Maine, which is where a
marginally cold airmass remains for mid-April standards. Within
bands of heavier precipitation and areas above 2,000 ft elevation,
ptype should remain mostly snow or a mix of rain/snow. Snowfall
amounts through Sunday night are generally expected to remain
around 1-3", but with locally higher amounts around Mount Katahdin
(40-70% probabilities for >4") into east-central/northeast Maine
(10-40% probabilities for >4").


...Northern to Central Rockies...
Days 1-2...

A strong mid-level shortwave over the northern Great Basin this
afternoon will strengthen across western MT this evening.
Associated frontal boundary will sweep eastward into the Plains,
with temperatures forecast to fall behind the front and lower snow
levels below 4000ft as precipitation lightens and then ends from
west to east on Sunday/Sunday night. By then, the cold front will
slow across the central Rockies, helping to wring out some snow
over CO. The system will be fairly progressive overall but it could
snow moderately (>1"/hr) for a time tonight over NW MT. WPC
probabilities for at least 6 inches of snow for the period are
highest around Glacier NP, across the Little Belt Mountains, and
near Yellowstone NP (30-60% probs). Over the CO Rockies, amounts
will be lighter overall, but some areas could still see several
inches of snow (above 10,000ft). There, WPC probabilities for at
least 6 inches of snow are 40-60% on Day 2.


...Western Great Lakes...
Days 2-3...

The mid-level low exiting MT Sunday will strengthen more over the
northern Plains as a 120kt jet streak develops over Iowa. An area
of surface low pressure will deepen and help foster an expanding
area of precipitation over the northern Plains into the Upper
Midwest. Temperatures will be marginal to mild initially, but once
the low tracks into Lake Superior, north to northwest winds will
rapidly bring in colder air to northern areas of MN and eventually
into the U.P. of Michigan Monday night into early Tuesday. Snow
will become more widespread with accumulation likely over most of
the MN Arrowhead and northern WI into the U.P. of Michigan. WPC
probabilities for at least 4 inches of snow through 00Z Wed are low
(10-30%) in northwest MN and moderate (40-70%) in the MN. For areas
downwind of Lake Superior from far northern WI through the U.P. of
Michigan, higher amounts are likely Monday night through Tuesday,
with WPC probabilities depicting 10-40% chances for at least 8
inches of snow.


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


Snell/Fracasso