Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
448 PM EDT Fri Apr 4 2025

Valid 00Z Sat Apr 05 2025 - 00Z Tue Apr 08 2025

...Southern Rockies and the Southern High Plains...
Days 1-2...

A cold front tracking south through CO this afternoon will push
south through NM tonight as an upper low tracks over the southern
borders of AZ/NM. Moisture ahead of this low combined with the low
level cold behind the front will support heavy mountain snow on the
eastern side of the southern Front Range, Sangre De Cristo and
Raton Mesa through this evening before shifting south through the
Sacramento Mtns Saturday morning. Upslope flow and increasing lift
should enable snow rates of 1-2"/hr to work their way south later
this afternoon through tonight per the 12Z HREF. 1"/hr rates also
shift east over the southern High Plains of NM into the TX
Panhandle. Day 1 snow probabilities for >8" are 50-80% in terrain
from the Raton Mesa through the Sacramento Mtns especially
including the Sangre de Cristos which have 50-70% chances for >12".
Day 1 probs for >4" are 30-60% from the lower reaches of the Raton
Mesa through much of eastern NM and into the Staked Plain of the
western TX Panhandle south of the Pecos where snow persists into
Saturday evening.


...Northern New England...
Days 1/2...

Expect a wintry mix from the White Mountains of NH through western
Maine Saturday/Saturday night. While the airmass is not as cold as
the more recent winter storm that took place earlier this week,
high pressure over Quebec will provide a weak source of sub-
freezing boundary layer temps. As 850-700mb WAA and 300K isentropic
ascent amidst brisk SWrly flow aloft increases, a ribbon of
850-700mb areal-averaged FGEN will support a band of moderate- to-
heavy precipitation that runs directly over the marginally cold
air-mass in northern New England on Saturday. Precipitation may
briefly start out as snow (staying all snow longest over northern
Maine), but the burgeoning nose of >0C temps at low-levels will
inevitably switch any snow to a sleet/freezing rain mixture from
the Whites to western Maine Saturday afternoon. A weak CAD
signature will linger longest along the Maine/Quebec border
through Saturday night. By Sunday morning, the warm front lifts far
enough north to have plain rain be the primary precipitation type.

Day 1.5 WPC probabilities for ice accumulations >0.1" are 30-70% from
the Whites through western Maine with 40% probs for >0.25" in the
Presidential Range of the Whites. Moderate impacts from this icing
are forecast in higher elevations per the WSSI.


...Michigan...
Day 3...

A potent reinforcing shortwave trough swings south of a cold-core
low over Hudson Bay Sunday, reaching the L.P. of Michigan on
Monday. PVA, low level FGEN, and Great Lakes moisture combine to
produce a band of snow Sunday evening over Lake Superior that
shifts south-southeast over the U.P. Sunday night and the L.P.
Monday morning. Trailing cold air advection then produces some
lake- enhanced snow showers behind the front. Day 3 PWPF for >6"
are 10-30% across the northern L.P.


Jackson