Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
329 AM EST Wed Mar 02 2022

Valid 12Z Wed Mar 02 2022 - 12Z Sat Mar 05 2022

...West...
Days 1-3...

Moisture plume into the Pac NW will continue into southwestern
Oregon Day 1 and continue across northern Idaho as the arcing jet
moves downstream. Snowfall will be light as snow levels remain
rather high around 5000-6000ft but will start to trend lower by
Day 2. On Thursday, Upper trough off the West Coast will separate
into a northern shortwave moving through Washington and a southern
closed low moving into Southern California. The northern portion
will bring several inches of snow to northern Idaho and perhaps
more to northwestern Montana on the right entrance region of the
tail-end of the long northern stream jet, coupled with upslope
flow as surface low pressure move across the Bitterroots. On Day
3, upper low over Southern California will be quickly followed by
another upper low from the northwest (dropping out of the
Northeast Pacific) into northern California as the southern upper
low weakens through the Four Corners. Models have had a tough time
resolving the several players in the forecast and have trended a
bit slower with the heavier QPF into the Sierra, but this will
still yield a light to modest snow for some areas including
Southern California and the mountain ranges outside Los Angeles
and San Diego. Snow levels will fall to 4000-5000ft by the start
of Day 3 as the cold pool aloft moves overhead. Widespread light
snow is expected across much of the Great Basin eastward to the
central Rockies as the trough, in its several pieces, moves
through. The Sierra will see most of the snow with over 10 inches
likely for many areas.


...Northeast...
Day 1...

Clipper system over the Upper Midwest this morning will zip
quickly through the Great Lakes into the Northeast today as low
pressure deepens into Maine by early Thursday. Jet stream will dig
into the Mid-Atlantic with modest diffluence over New York and New
England, but with only modest moisture in place. Cold advection
across Ontario and into the Adirondacks will promote a few inches
of snow there and over the Green Mountains in Vermont. WPC
probabilities of at least 4 inches of snow are generally low to
moderate (10-50%).


...Upper Midwest...
Day 3...
Western troughing will only start to organize surface low pressure
over the central Plains by the end of Day 3, with some light warm
advection snow into the Upper Midwest closer to Lake Superior and
mixed precipitation to the south over southern/eastern Minnesota
eastward into Wisconsin. WPC probabilities are very low (<10%) for
significant snow or icing through 12Z Saturday with much more
precipitation thereafter over the western Great Lakes as well as
back to areas east of the central Rockies.



For Days 1-3, the probability of significant icing of at least a
quarter of an inch is less than 10 percent.


Fracasso