FOUS11 KWBC 080849
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
449 AM EDT Sun Mar 8 2026

Valid 12Z Sun Mar 08 2026 - 12Z Wed Mar 11 2026

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

Days 1-3...

Deep mid-level low drifts southeast over the Gulf of Alaska today
through Monday with the trough south of it digging across
Washington with a strengthening zonal jet before stalling/lifting
north through midweek. Snow levels over the WA Cascades drop
through Monday morning from the current 6000ft to near sea level
Monday/Monday night. The first slug of moisture from this system is
currently pushing down the south end of Vancouver Island with
higher elevation 1"/hr snow rates over the north WA Cascades per
the 00Z HREF. Then renewed precip arrives this evening when snow
levels dip below 3000ft/Snoqualmie Pass level and reach 1000ft or
less by 12Z Mon. Onshore flow and precip persist pretty much
through the rest of this week in western WA. Will need to continue
to monitor Puget Sound convergence banding Monday night when snow
levels approach sea level for accumulating snow potential in the
greater Seattle metro. Otherwise, it's upslope based snow for the
WA Cascades with and inland axis shifting south down the MT Rockies
this afternoon through Monday with snow levels in the moderate
precip rates generally 4000-6000ft. Day 1 snow probs for >6" are
around 50% near Snoqualmie Pass and 50-80% in the higher NW MT
Ranges including the Lewis and Bitterroots. Day 2 snow probs for
>8" are 60% near Snoqualmie Pass and 30-50% in the northern/Red
Lodge Absarokas. Day 3 snow probs for >8" are 85% near Snoqualmie
Pass and 30-60% in the Bighorns of northern WY.

The prolonged duration of moderate to heavy snow for the WA
Cascades at low snow levels through midweek will be quite remarkable.


...Northern Great Lakes...

Day 3...

A reinforcing trough rounding the Gulf of Alaska low today digs
across WA late Monday where it begins to draw the cutoff low
currently off the northern Baja Peninsula toward Texas. The sheared
southern stream remnant trough and the northern stream trough from
WA approach each other Tuesday night over the south-central Plains,
promoting strong inverted troughing downstream across the Midwest.
North of this trough axis will be overrunning precip with a
transition from a wintry mix to snow. These defined ptype changes
will need to be closely monitored as accumulating ice and snow are
likely. Day 3 snow probs for >4" are 40% in the MN Arrowhead and
30% in the western coastal U.P. South of this swath is the risk for
freezing rain with probs for >0.1" currently 10-30% over the
eastern U.P. and northern L.P. Since the low will track along/near
the axis of the inverted trough, duration of wintry precip over the
northern Great Lakes will persist into/through Wednesday, so stay
tuned for updated location and magnitude forecasts for snow and ice.


Jackson


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