Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
341 PM EDT Thu May 05 2022

Valid 00Z Fri May 06 2022 - 00Z Mon May 09 2022


...Pacific Northwest...
Days 2-3...

A pair of weather systems will bring increasing chances for
accumulating snow, some heavy, to parts of the Pacific Northwest
mountains this weekend. The first system arrives Friday into
Saturday as a closed mid-level low approaches Oregon Friday and
then begins to open up Saturday. The associated lift and moisture
plume moving onshore will support heavy snow for the OR Cascades,
extending northward some into the WA Cascades but also eastward
over to the central Idaho and northwest MT ranges. Above 6-7 kft,
heavy snow is likely and WPC probabilities for 4 inches are
moderate to high with slight signals for 8 inches or more for the
Oregon Cascades during Day 2.

Beginning late Saturday through Sunday, a stronger compact mid
level closed low approaches the Oregon coast and a 130 to near 150
kt jet noses at northern California. This system will be a bit
colder and with heights lower than the first system, expect snow
levels to drop to around 2-3 kft in places. The favorable left
exit region dynamics supports another round of snow, some heavy,
for the OR Cascades but also extending southward into the northern
California ranges and parts of the Sierra including parts of the
Klamath Mountains. There is also an increasing signal for heavy
snow to spread eastward across the central Idaho ranges and toward
Yellowstone in northwest WY. For Day 3, WPC probabilities for 4
inches are slight to moderate for OR Cascades southward into the
northern California ranges

For days 1-3, the probability of significant icing is less than 10
percent.

Taylor