Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
242 AM EDT Fri Oct 28 2022

Valid 12Z Fri Oct 28 2022 - 12Z Mon Oct 31 2022

...Pacific Northwest...
Days 1-2...

Mid-level shortwave and attendant surface cold front will drive
through the Pac NW today, bringing a band of precipitation through
the region. Snow levels will be high, above 6000ft, with
accumulations of a few inches over the higher Cascade peaks and
into far northeastern WA/northern ID. On Saturday, flatter flow
will still maintain an onshore fetch of moisture, but limited to
the northern WA Cascades where a few inches are possible.

...Day 3...
On Sunday, a 150kt jet streak will move through British Columbia
as a surface boundary approaches from off the coast. An
atmospheric river will bring a surge of moisture (PW anomalies
+1.5 to +2 sigma and IVT > 500 kg/m-s) and multi-inch QPF to the
Olympic Peninsula and the central/northern WA Cascades. With it
will be mild air as well, raising snow levels to 6000-7000 ft,
confining heavy snow totals to the highest peaks where
accumulations over 6 inches is likely.


The probability of significant icing greater than 0.25" is less
than 10 percent.


Fracasso