FOUS11 KWBC 050659
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
259 AM EDT Sun Apr 5 2026

Valid 12Z Sun Apr 05 2026 - 12Z Wed Apr 08 2026

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

Scattered precipitation across northern New England early this
morning will become more widespread through this afternoon as a
warm front lifts northward towards the region ahead of a system
approaching from the Great Lakes. Moisture will continue spreading
northward from the Gulf and ascent isentropically atop the warm
front, expanding the precipitation shield but also driving a warm
nose >0C northward as Canadian high pressure retreats. The timing
of the heaviest wintry precipitation is likely prior to
18Z/Sunday, during which time a mixture of snow, sleet, and
freezing rain will occur before transitioning to all rain. Total
accumulations of any wintry precipitation are expected to be
modest, but still produce impacts to travel as reflected by 20-40%
chance for moderate impacts in the WSSI-P, focused over the higher
terrain of NH and ME. Freezing rain is likely to produce the most
impacts as at least a glaze of ice is possible for the higher
terrain of northern New England. However, significant icing
exceeding 0.1" is expected to be confined to just the higher
terrain of NH and ME.

Following the cold frontal passage this evening, strengthening CAA
along with modest height falls and steepening lapse rates will
allow for upslope snow showers and snow squalls from the
Adirondacks through northern VT/NH/ME into Monday.

...Great Lakes... Days 1-3...

A fast moving and compact shortwave diving out of Manitoba will
race southeast and cross the western Great Lakes Monday before
becoming embedded in the broad cyclonic flow across the Northeast
on Tuesday. This shortwave will help develop a weak wave of low
pressure along an inverted surface trough tracking southeast across
Michigan Monday. Any warm advection snowfall may stay just north
of the region, but sufficient cold advection behind this wave will
drop 850mb temps down to below -15C, sufficient for late season
lake effect snow (LES) and diurnal snow shower activity as lapse
rates steepen atop the slowly warming Great Lakes. Heavy snow is
likely to develop within this CAA south of Lake Superior,
especially along the western U.P. of MI, and downwind of Lake Erie
along the shores of western New York. Here, WPC probabilities for
4+ inches are 40-60% in the MI U.P. for Days 1-2 and 50-80% in far
western NY Days 2-3.

Snell/Weiss
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS11 KWBC 060710
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
310 AM EDT Mon Apr 6 2026

Valid 12Z Mon Apr 06 2026 - 12Z Thu Apr 09 2026

...Missouri Valley/Corn Belt... Day 1...

An interesting evolution during the second half of Day 1 (00Z -
12Z Tuesday) could result in a very narrow corridor of heavy
snowfall from eastern Nebraska into southwest Iowa and far
northern Missouri. A modest shortwave dropping across the Central
Rockies will cause weak height falls and broad divergence across
the region Monday night into Tuesday morning. At the same time, a
potent NW to SE oriented jet streak will arc southward on the
upwind side of a trough moving over the Great Lakes/Northeast,
leaving favorable RRQ diffluence overlapping the best mid-level
divergence. This mid- level pattern will push a cold front through
the region today, but it is likely that this front will begin to
kink and return northward with warm advection Tuesday morning as
850mb flow returns to the S/SW creating a narrow corridor of
impressive fgen as moist isentropic upglide ascends the boundary.

The overlap of this moist isentropic ascent with the RRQ of the jet
streak aloft will create a narrow stripe of intense 850-600mb fgen,
creating a streak of heavy precipitation. With the most intense
ascent expected to lift into the deepening DGZ (50% chance of at
least 50mb of DGZ depth according to the SREF), dynamic cooling
should overcome the generally marginal thermal structure during the
overnight hours and absent of the April sun-angle, leading to a
stripe of heavy snow with snowfall rates potentially reaching
1"/hr. There remains some uncertainty into the placement of this
band due to its very narrow nature, as well as the intensity of
any of the snow. WPC probabilities have increased, and now feature
a 30-60% chance of at least 4" by Tuesday morning from east-
central NE through southwest IA, potentially leading to a hazardous
morning commute.

...Great Lakes & Northeast... Days 1-2...

Compact shortwave digging out of Manitoba will race southeast,
crossing the Upper Midwest and Great Lakes today before becoming
embedded into the more synoptic cyclonic flow across the Northeast
by Tuesday. This will help spawn a weak wave of low pressure along
an inverted surface trough, with locally enhanced moist advection
in the vicinity of this low leading to a swath of light to moderate
snowfall. The heaviest synoptic snow should be generally north of
the international border, but CAA in the wake of this impulse will
push 850mb temps down to around -15C, producing a favorable
environment for lake effect snow (LES) in the favored NW snow belts
downstream of the Great Lakes. The duration and intensity of this
LES may be somewhat modest, but significant accumulations exceeding
4" are still possible (30-70% chance) across the Huron Mts of the
MI U.P. on D1, and 10-20% along the Chautauqua Ridge east of Lake
Erie on D2 on north through the favored upslope regions of the
Adirondacks and Green Mts.

Snell/Weiss

$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS11 KWBC 070717
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
317 AM EDT Tue Apr 7 2026

Valid 12Z Tue Apr 07 2026 - 12Z Fri Apr 10 2026

...Northern Adirondacks, Green & White Mts... Day 1...

Strung out vorticity associated with a compact shortwave will swing
from the Great Lakes to the Northeast today. The modest height
falls and PVA will lead to a compact low pressure developing along
an inverted trough, and as this feature moves east it will bring
periods of moderate to heavy snowfall through early tonight. This
event will contain two primary mechanisms for locally heavy snow.

The first will be along the inverted trough immediately ahead of
the wave of low pressure. In this area, the total snowfall is
expected to be minimal, but periods of convective snow showers are
expected as low-level convergence drives ascent into an airmass
with modest instability (SBCAPE 200-300 J/kg). With pockets of
low-level fgen additionally driving ascent, some areas, especially
across Upstate NY and central/southern New England could receive
multiple rounds of snow showers with briefly heavy snow rates,
gusty winds, and periodic visibility restrictions.

The more substantial snowfall accumulations are expected behind the
wave of low pressure as CAA develops to produce low-level fgen, and
NW flow drives substantial upslope enhancement into the Adirondacks
and Greens. The coverage and intensity of this snowfall is again
expected to be modest, but where upslope flow is most pronounced
and overlaps with the leading weak warm advection, WPC
probabilities suggest a 40-70% chance of 4+ inches of snow,
especially across the White Mts of NH and ME. Probabilities for at
least 2 inches of snow are 40-60% across a larger region
encompassing the northern Adirondacks and Green Mts of VT.
Developing deformation, although modest, overlapping this CAA could
cause this swath of snowfall to progress all the way to the
Atlantic coast of Massachusetts with a corridor of heavy snow rates
reaching the Portland/Boston area Tuesday evening, albeit with
minimal accumulations.


Snell/Weiss


$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS11 KWBC 080632
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
232 AM EDT Wed Apr 8 2026

Valid 12Z Wed Apr 08 2026 - 12Z Sat Apr 11 2026

...Sierra Nevada... Day 3...

Precipitation returns to the West Coast late this week and early
this upcoming weekend as a closed upper low slowly approaches the
California coastline on Friday and interacts with a separate system
dropping southeast from the Gulf of Alaska late Friday night. Snow
levels are forecast to remain rather high through Saturday morning
above 8000ft and higher than many major passes. Current WPC
probabilities valid through the end of Day 3 are low (20-40%) for
at least 6 inches of snowfall across the Sierra Nevada and mostly
for remote locations with an elevation above 9500ft. However, snow
levels are expected to lower by the very end of the short range
forecast period (12Z Saturday) potentially down to around 7500ft
and should continue to lower somewhat throughout the weekend into
next week.

Snell

$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)