FOUS11 KWBC 090910
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
510 AM EDT Mon Mar 9 2026

Valid 12Z Mon Mar 09 2026 - 12Z Thu Mar 12 2026

...Pacific Northwest Through The Northern Rockies...

Days 1-3...

Active winter weather continues across the WA Cascades and northern
Rockies through this weekend with particularly low snow levels
(especially for March) persisting into Wednesday.

A powerful zonal jet south of a Gulf of Alaska low will continue to
push across the WA/OR border as it continues to intensify to
150kt+ through tonight. A tight baroclinic zone has established
over central OR to southern MT with a moisture axis pushing across
western WA with showery activity through this evening under a
passing trough axis before tapering off under brief ridging
overnight. This is the coldest portion of this storm, but precip
should be pretty localized which may limit the snow coverage around
the greater Seattle metro tonight as snow levels dip below 500ft
MSL. Day 1 snow probs for >8" are over 50% above about 2000ft on
the WA Cascades and around 30% in the Bitterroots and just south
of Glacier NP.

Snow levels then rise to 1500ft on the Cascades Tuesday as
moisture content in the onshore flow increases along with snow
rates. Day 2 snow probs for >8" are over 50% above about 2500ft on
the WA Cascades and 40% for the Red Lodge/northern Absarokas and
higher Bighorns.

The next jet streak and onshore moisture surge increase is
Wednesday, again right into western WA. Snow levels quickly rise
above 3000ft Wednesday afternoon with high precip rates. Day 3 snow
probs for >12" are over 50% above 3500ft and around 60% in the
Bitterroots and Lewis Range. At least two more days of heavy
mountain snow, so stay tuned for further details on that forecast.

...Northern Plains through the Northern Great Lakes...

Days 2-3...

A southern stream cutoff low off Baja will eject east and open into
a trough before reaching TX Tuesday night. Considerable
sub-tropical Pacific moisture will stream across Mexico and be
joined by west Gulf moisture that surges up the Plains. Meanwhile a
northern stream trough crosses the northern Rockies Tuesday with
an inverted trough developing from the southern Plains to Chicago
Tuesday night with surface low development over southeast MI early
Wednesday. The surging moisture will wrap around the surface
trough/developing low, forming a comma head and connecting fgen
band over SD to southern MN Tuesday night. North of the low track
expect swaths of wintry mix before being all snow over far northern
WI and the U.P. Confidence is rising on a dry slot extending
through this wintry mix zone which complicates the QPF in this
case. There is decent storm track and QPF coverage from the 00Z
AIGFS/EC-AIFS and GFS on heavy banded snow over the U.P. and
sufficient QPF over the wintry mix zone for concerning freezing
rain accumulations. Day 2.5 snow probs for >6" are 40% in the Huron
Mtns and 30% along the central U.P. northern shore though these do
seem a bit suppressed. Ice probs have risen despite the risk for
dry slotting with the northeast L.P. having Day 2.5 probs for
>0.25" peak around 40%. Interestingly the WSSI-P moderate impact
ice has a peak around 50% in a similar area. Overall this is a
fairly progressive storm, much more so than the prolonged ice storm
last March in this area.

...Northern New England...
Days 2/3...

Surface low pressure downstream of a northern stream trough
over the Upper Midwest tracks across New York on Wednesday before
crossing northern New England Wednesday night. A warm front
downstream of the low will extend ENE into New England, and then
lift through northern Maine with strong moisture advection driving
a warm nose over residual cold air from high pressure tracking
north of Maine Tuesday night. A wintry mix of sleet and freezing
rain spreads generally north of NY/VT and across north-central
Maine where Day 3 ice probs for >0.1" are 40-60%. Thermals likely
remain cold enough for the northern tip of Maine where Day 3 snow
probs for >6" are 40-60% in northern Aroostook Co.

Jackson

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