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FOUS11 KWBC 050732
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
332 AM EDT Sat Apr 5 2025

Valid 12Z Sat Apr 05 2025 - 12Z Tue Apr 08 2025

...Southern Rockies and the Southern High Plains...
Day 1...

A 700mb low tracking across southern New Mexico this morning has
all the necessary ingredients at its disposal for a classic April
winter storm in the southern Rockies and High Plains. Modest
700-300mb moisture aloft will overrun an air-mass that is becoming
increasingly colder through two methods: CAA in wake of the cold
frontal passage, and the other being dynamic cooling aloft within
the developing deformation axis. The mountain ranges of the
southern Rockies (Sangre De Cristo, southern Front Range, San
Juans, Sacramentos) will see the heaviest snowfall rates which can
surpass 2"/hr in some cases through this morning. As the 700mb low
emerges over eastern New Mexico, periods of heavy snow and gusty
winds will produce hazardous travel conditions across the High
Plains of eastern New Mexico, southeast Colorado, and the Texas
Panhandle through Saturday evening. There could be instances of
>1"/hr snowfall rates over eastern New Mexico and the Texas
Panhandle during the day. Snow should taper off across West Texas
Saturday night, while a brief burst of snow over central Oklahoma
could produce a swath of light snow as far east as southwest
Missouri.

WPC snowfall probabilities show moderate-to-high chances (50-80%)
for >8" in terrain from the Raton Mesa on south along the Sangre De
Cristo and all the way to the Sacramentos which have 50-70%
chances for >12". Much of east-central New Mexico along I-40 shows
moderate-to-high chances (40-70%) for snowfall totals >4"with low-
to-moderate chances (20-50%) in portions of the Texas Panhandle
between Amarillo and Lubbock. The WSSI shows a large footprint of
Moderate Impacts from the Southern Rockies and eastern New Mexico
to the Texas Panhandle with the Snow Amount and Blowing Snow impact
criteria being the primary drivers in the WSSI algorithm. Expect
hazardous travel conditions in these area today and into parts of
tonight.


...Northern New England...
Day 1...

Today, another round of wintry weather arrives from the White
Mountains of New Hampshire through western Maine that will continue
through Saturday night. The airmass is not as cold as the more
recent winter storm that took place earlier in the week, but high
pressure over Quebec will anchor 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 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.

WPC probabilities show moderate-to-high chances (50-80%) for ice
accumulations >0.1" from the Whites through western Maine with up
to 40% probs for >0.25" in the Presidential Range of the Whites.
The WSSI is depicting moderate impacts from this icing event within
the hardest hit areas of the Whites and western Maine.


...Michigan...
Days 2-3...

A vigorous 500mb vorticity maximum originating out of the Arctic
Circle several days ago will track south from southern Canada
towards Minnesota Sunday night. A 250mb jet streak oriented N-S
will place its divergent left-exit region over the Midwest Sunday
night and aid in the development of low pressure along a
strengthening 850mb front. A narrow band of moderate-to-heavy snow
will manifest itself on the northern periphery of the developing
storm system as it tracks across Michigan`s Mitten early Monday
morning. In addition to the primary band of snow, CAA via brisk
northerly winds will trigger lake-enhanced snow showers over
Michigan`s U.P. and the northern-most portions of Michigan`s
Mitten through Monday afternoon. Snow should finally taper off by
Monday evening as the storm races east. WPC probabilities show
low-to-moderate chances (20-50%) for snowfall accumulations >4" in
northern Michigan through Monday evening.

The wave of low pressure will continue its eastward progression
across the Great Lakes Monday afternoon and along the Northeast
U.S./southeast Canada border Monday night. Periods of light snow
are possible from the eastern Great Lakes to the northern
Appalachians Monday night and into Tuesday morning. Light
accumulations between a coating to as much as 2" are possible with
the highest elevations of the northern Appalachians having the best
odds of seeing the higher end of those snowfall accumulations.


Mullinax





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