Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
428 AM EDT Sat Apr 13 2024

Valid 12Z Sat Apr 13 2024 - 12Z Tue Apr 16 2024


...California across the Great Basin to the Colorado Rockies...
Days 1-3...

Low off the northern CA Coast will slowly pivot east through
tonight as it occludes/weakens. Sufficient moisture and height
falls allows heavy snow to shift from the Shasta/Siskiyou this
morning down the Sierra Nevada this afternoon. Heavy rates of 1-2"
can be expected in this brief burst of snow above snow levels
around 5000ft with Day 1 PWPF for >6" 50-80% over this terrain.

A shortwave rounding the low lifts up the Sierra tonight,
promoting surface cyclogenesis over the Great Basin and shifting
the heavy snow focus back north over the Shasta/Siskiyou east
through the Warner Mtns in the far northeast corner of CA into
Sunday with snow levels remaining around 5000ft. Day 2 PWPF for
>6"is 40-70% over this terrain. 

The low continues to drift east from the Great Basin to the CO
Rockies Sunday night through Monday. Height falls and sufficient
Pacific moisture brings Day 2.5 PWPF for >6" of 40-80% to the
south-central Utah ranges above 6000ft snow levels. Then, as the
low reaches western CO Monday, lee-side cyclogenesis focuses Gulf
of Mexico- sourced moisture up the Plains and into the CO Rockies
with snow levels above 7000ft. Day 3 PWPF for >6" is 40-90% for all
northern and western CO ranges.


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


Jackson