FOUS11 KWBC 100908
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
508 AM EDT Tue Mar 10 2026

Valid 12Z Tue Mar 10 2026 - 12Z Fri Mar 13 2026

...Cascades Through The Northern Rockies... Days 1-3...

...Washington Cascades Blizzard into Thursday...

Active winter weather continues across the WA Cascades and northern
Rockies through Friday night with particularly low snow levels
(especially for March) persisting through tonight.

A reinforcing shortwave trough rides a 150kt zonal jet positioned
south of a Gulf of Alaska low across the WA/OR border today. Low
snow levels (500ft or below) persist this morning over western WA
under the trough with snow levels rising to 1500ft this afternoon
as heights rise after the trough axis passage. Onshore flow
persists today with the next atmospheric river approaching tonight
with rates becoming moderate overnight with increasing winds. Day
1 PWPF for >8" is around 60% at Snoqualmie Pass and over 40% above
about 2000ft on the WA and northern OR Cascades as well as the Olympics.

A focused axis of 0.75 to 1" PW shifts across the western WA/OR
border Wednesday through Friday with a trough axis crossing early
Thursday. Powerful winds accompany the leadup to the trough axis
with 850mb winds of 40-60kt expected across the WA and northern OR
Cascades Wednesday night before easing into the 25kt range on
Thursday. Snow levels rise to 4000ft through Wednesday in the WAA
of the AR axis before dropping over WA into the 2000-3000ft range
late Wednesday night. Days 2/3 snow probs for >12" are quite
impressive, generally 50-80% above about 2500ft on Day 2 and 2000ft
on Day 3. Blizzard warnings are up for the WA Cascades through
Wednesday with the watch extending into Friday for this prolonged event.

This moisture axis extends inland over the northern Rockies through
this event. Snow levels rise there into the 4000-5000ft range
through Wednesday night before the moisture axis shifts south a bit
Thursday. Day 2 snow probs for >8" are 50-80% for the Bitterroots
through the Lewis Range before focusing on the Bitterroots,
Anaconda Range and southern Lewis Range on Day 3.

...Northern Plains through the Northern Great Lakes... Days 1-2..

Broad troughing over the northern tier of the CONUS focuses onto a
more defined northern stream trough over the northern Rockies today
which sweeps across the northern Plains tonight, the Upper Midwest
Wednesday, and the Great Lakes Wednesday night. A sinewy band of
moderate snow over north-central MN, northern WI, and the western
U.P. is from fgen on the leading edge of a developing inverted
trough developing downstream of the forming trough axis. An
additional factor in the developing storm is a cutoff low currently
over the Sea of Cortez that ejects to TX through tonight. This
reinforces the downstream inverted trough and promotes surface low
pressure development over IL tonight. Broad cyclonic flow develops
tonight with fgen snow banding over the north-central Plains
through central MN up through northern WI and the western U.P.
pivoting down to eastern Neb. Dry slotting is well defined now in
guidance south of the snow and north of the surface low. Mixed
precip will develop through this zone over central WI and
especially northern L.P. of MI. Day 1.5 snow probs for >4" are over
40% from northern WI through the north shore of the eastern U.P.
with embedded 60% probs for >8" in the Huron Mtns. Day 1.5 probs
for >0.25" are 40-60% in the northern U.P. east of I-75.

...Far Northeast... Days 2-3...

Potent northern stream shortwave lifting steadily eastward from the
Central Plains will cross into the Great Lakes/Ohio Valley Thursday
while amplifying. Downstream of this trough amplification, a
meridionally arcing jet streak will favorably influence ascent
through the right entrance region to help strengthen a surface low
tracking from lower Michigan through Ontario, before tracking north
of Maine late Wednesday night. Downstream of this system, moisture
advection will intensify from the Gulf, driven by potent 850mb
WAA, which will additionally surge the surface warm front
northward. The combination of the deep layer ascent with the
resulting fgen (as a result of the WAA) will create heavy
precipitation along the international border with Canada and then
into northern Maine. Precipitation will likely start as snow across
northern Maine, but everywhere else, and then later in the period
across northern Maine, a mix of sleet and freezing rain, eventually
becoming rain, is expected, as the warm nose surges northward. Day
2 ice probs for >0.25" are 30-50% in interior north-central Maine
with Day 2 snow probs for >6" limited to northern Aroostook Co.

Some LES can be expected in the wake of this low off Lake Ontario
late Thursday.

...Northern Plains to Northern Great Lakes... Day 3...

The potent shortwave trough axis crossing northern WA early
Thursday really amplifies over the northern Plains Thursday before
rapidly developing into a major low pressure system over the Upper
Midwest Thursday night. This progressive system will be on the
leading edge of a 150kt WNWly jet. A strong wind field and heavy
snow bands will develop with this low. Day 3 snow probs for >6" are
30-60% over northeast ND and across northern WI, much of the U.P.,
and the North Shore of MN. This coming on the heels of the
low tonight into Wednesday will make for a notable late-season
impact to the Upper Midwest/northern Great Lakes.

Jackson

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