Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
204 PM EDT Thu Apr 2 2026

Valid 00Z Fri Apr 03 2026 - 00Z Mon Apr 06 2026


...Upper Midwest through the Great Lakes...
Day 1...

...First of back-to-back significant late-season winter storms
wraps up late tonight into early Friday morning...

Ongoing snow, sleet, and freezing rain associated with a
strengthening surface low tracking across the Upper Midwest and
northern Great Lakes will continue this evening before ending late
tonight into early Friday morning. Freezing rain and icing will
mostly be confined to northern WI and the U.P. of Michigan,
transitioning to sleet and snow with northern and western extent.
Additional ice accumulations of more than 0.1 inches are possible
(30-50% chance), leading to storm total icing of as much as 0.5
inches, resulting in treacherous travel, and scattered power
outages. Colder air wrapping in on the back side of the departing
system may allow for some areas predominantly experiencing mixed
precipitation to briefly change to snow before ending, but any
accumulation would mainly be light with little additional impacts.

The heaviest remaining snow will primarily be focused across
northern Minnesota, where an additional 4+ inches is possible
(10-30% chance, locally higher in the Arrowhead) through early
Friday morning. Snowfall rates may approach 1" per hour at times,
especially this evening, before gradually lessening as the night
goes on. Reduced visibility and snow-covered roads will continue to
make travel difficult before conditions gradually improve late
tonight into early Friday morning.

Key Messages are in effect for this system and are linked
below (Key Messages #1).


...Northern New England...
Days 1 & 3...

Two rounds of mixed precipitation will bring modest accumulations
of snow, sleet, and freezing rain to Northern New England through
the weekend, but with considerable impacts across narrow corridors
due to the mixed precipitation types.

The first event will occur D1, generally 06Z/Fri - 00Z/Sat. This
first round of precipitation will be driven by robust WAA surging
northward from the Gulf ahead of a significant storm system moving
through the Great Lakes and Ontario, Canada. Initially, this
precipitation will begin as snow in northern VT, NH, and ME as cold
Canadian high pressure slowly retreats, but as the WAA pushes the
warm front northward, especially without any strong dry-bulb
cooling to offset the warmth, p-type transition will rapidly occur
to sleet, freezing rain, and eventually rain for the entire area.
This evolution supports the heaviest accumulations being confined
to just far northern ME where WPC probabilities for snow exceeding
4" are 30-50%. More icing than snow is expected across the rest of
Northern New England as reflected by WPC probabilities for at least
0.01" above 50% for much of the Greens, Whites, and higher
elevations of north-central ME, with locally more than 0.1"
possible (30-50%) across western ME and northern NH.

The first system kicks out Friday evening, and Saturday should be
dry across the area. However, a second system will track almost
identically to the first system across the Great Lakes and into
Ontario, spreading moisture into New England along the warm front
through return flow/WAA out of the Gulf. This system will again
encounter a rapidly retreating Canadian high pressure, so once
again a mix of snow, sleet, and freezing rain, is likely, with the
primary difference between the Sunday event and the Friday event
being a slightly warmer starting condition (so less snow). However,
a few inches of snow are again possible across far northern ME (WPC
probabilities reach 50-70% for 2"), with locally as much as 0.1"
of is possible (30-50%) for the higher elevations of northern NH
and interior western ME.


...Northern/Central Rockies, Northern Plains, & Upper Midwest...
Days 1-3...

...Second of back-to-back systems will bring additional heavy snow
and icing to portions of the region into the weekend...

After the first low moves away Friday morning, the region will get
a very brief respite (in some places less than 18 hours) before the
next significant low pressure system impacts the area.

This next low will develop in response to a sharpening mid-level
trough which is expected to become a pronounced closed low with
height anomalies falling below the 10th percentile according to
NAEFS, which will work together with a meridionally arcing jet
streak to produce a deepening cyclone as it tracks from the lee of
the CO Rockies into the Great Lakes. This evolution will result in
widespread significant deep layer ascent through height falls and
jet dynamics, leading to widespread precipitation from the
Northern/Central Rockies, through the Northern Plains, and into the
Great Lakes, before this system departs into Canada Saturday night.

Moisture accompanying this system will also be significant, aided
by both Pacific moisture flooding eastward on modest IVT, and
increasing low-level moisture on southerly WAA emerging from the
Gulf. At the same time, mesoscale ascent will begin to intensify
as low to mid level fgen increases to drive omega into a TROWAL
pivoting around the cyclone as the theta-e ridge surges
north/northwest. The deep layer ascent will likely yield widespread
modest precipitation rates for snow and mixed-precipitation, but
the setup does appear to support a pivoting band of heavier
snowfall beneath the TROWAL where deformation maximizes W/NW of the
low. The depth of the upper low supports a strong band, and the WPC
prototype snowband tool indicates more than 1"/hr snowfall rates
being likely from the Dakotas through northern MN.

Where this band pivots the longest, WPC probabilities indicate a
high risk (>70%) for at least 8 inches of snow from far northern SD
through southern ND and into much of northern MN. Within this band,
more than 12 inches (isolated 18 inches) is also possible.
Southeast of this heaviest snowfall where the robust WAA pushes a
warm nose northward to cause p-type transition, WPC probabilities
indicate a high risk (>70%) for at least 0.1 inches of ice from
eastern SD through northern WI and the western U.P. of MI, with
locally significant ice of 0.25 - 0.5 inches possible (30-50%) in
far northern WI and into the U.P. This ice and snow falling atop
areas impacted from storm #1, will likely lead to prolonged
significant impacts to travel and infrastructure, including power
outages.

In addition, and primarily on D1 as the storm begins to get
organized across the Plains, mountain snow will be widespread for
the Northern and Central Rockies. This snow will be supported by
onshore Pacific moisture and accompanying mid-level ascent, with
local enhancement likely as a cold front pushes east leading to
upslope flow. Snow levels will fall to around 3000-4000 ft,
bringing considerable impacts to many areas passes, and WPC
probabilities for at least 6 inches are above 70% across the
Absarokas, Tetons, Big Horns and northern CO Rockies.

Key Messages are in effect for this system and are linked
below (Key Messages #2).

Weiss/Miller



...Winter Storm Key Messages are in effect. Please see current
 Key Messages below...

https://www.wpc.ncep.noaa.gov/key_messages/LatestKeyMessage_1.png

https://www.wpc.ncep.noaa.gov/key_messages/LatestKeyMessage_2.png