FOUS11 KWBC 100848
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
448 AM EDT Mon Mar 10 2025

Valid 12Z Mon Mar 10 2025 - 12Z Thu Mar 13 2025


...The Bitterroots... 
Day 1...

A plume of Pacific moisture continues to push northeast from
northern OR through western MT this morning as a quick-moving 
northern stream shortwave trough of modest amplitude shifts east
over the northern Rockies. Moderate snow rates can be expected
above the roughly 4000ft snow levels in this plume that will be
focused on the Bitterroots along the ID/MT border this morning. Day
1 PWPF for >6" additional snow after 12Z is 30-60% along the
Bitterroots and toward the western slopes around Glacier NP.


...Pacific Coast... 
Days 2/3...

...Impactful heavy snow for California terrain Wednesday and
Thursday. See Key Messages linked below...

A powerful and deep trough digs off the West Coast Tuesday night
before shifting onshore Wednesday night through Thursday. The 
orientation of this trough, with its base digging south from the 
Central CA to Southern CA coasts Thursday brings a fairly short
lived surge of Pacific moisture that when combined with upslope
flow and height falls from the approaching trough brings a potent
heavy snow event for the length of California. This heavy snow
begins in the Klamath and CA Cascades late Tuesday night and the
length of the Cascades Wednesday into Thursday and SoCal ranges
Thursday. Snow levels of 4000 to 5000ft can be expected during the
heaviest snow for all California terrain. Day 3 PWPF for >18" is
60-90% for the highest Klamath/CA Cascades and 70-100% for the
length of the Sierra Nevada.

Lighter precip rates are expected over WA/OR which will be well
north of the base of the trough. Snow levels on Wednesday are close
to 3000ft in WA and 4000ft in OR. Day 3 PWPF for >6" are 50-70% in
the WA/OR Cascades as well as the Sawtooths of ID.

Snow and wind will spread across the Intermountain West and Rockies
Thursday into Friday before rapid development occurs over the
Plains as noted in the Key Messages and the medium range discussion (PMDEPD).

The probability of significant icing is less than 10 percent. 

Jackson

...Winter Storm Key Messages are in effect. Please see current 
 Key Messages below...

https://www.wpc.ncep.noaa.gov/key_messages/La...

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