Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
345 PM EST Sun Dec 31 2023

Valid 00Z Mon Jan 01 2024 - 00Z Thu Jan 04 2024

...Great Lakes & Central Appalachians...
Days 1 and 3...

A clipper system tracking from southern Lake Michigan to northern
Pennsylvania through this evening. Bands of snow wrapping around
this low will continue across southwest WI/northern IL/IN and the
L.P. of MI into this evening with the heaviest snow likely in
northwest Indiana as northern flow maximizes fetch off Lake
Michigan. Day 1 PWPF (starting at 00Z) are 50-80% for >2" in
northwest IN with potential for 4" or so should the snow band
persist.

Meanwhile, a few rounds of upslope slow occur over the central
Appalachians both in westerly flow ahead of the system into this
evening and in northwesterly flow behind late tonight/Monday. Day
1 WPC PWPF shows low chances (around 10%) for additional >4"
totals in some of the higher peaks and more
topographically-favored upslope areas of eastern West Virginia,
Garrett County, Maryland, and the Laurel Highlands.

Another clipper Tuesday night/Wednesday brings lake effect snow
across the Great Lakes with NWly/Wly flow bringing some
probability for >4" to favored parts of the U.P. of MI and to the
Tug Hill east of Lake Ontario.


...California...
Day 3...

The next digging low from the Pacific reaches the OR/CA border
Tuesday and looks to track southeast to central NV through
Wednesday. Like the most recent, this system will direct an
atmospheric river north up the West Coast ahead of the associated
cold front with 1" PW in the plume, though snow levels look to
peak at only 6000ft per the NBM.  Heavy snow reaches the higher
terrain of the Klamath/Siskiyou Tuesday evening and the Sierra
Nevada early Wednesday. The system is fairly progressive with
generally up to 12 hours of heavy snow for any of these particular
areas. Snow levels dip to around 5000ft by the time the heavier
rates cease. Day 3 PWPF is 40 to 70% for snow >6" along the length
of the Sierra Nevada as well as the higher Shasta/Siskiyou and
Trinity Alps.


The probability of significant ice across the CONUS is less than
10%.


Jackson