Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
456 AM EDT Tue Apr 14 2020

Valid 12Z Tue Apr 14 2020 - 12Z Fri Apr 17 2020

...CO to Southern High Plains...

Day 1...
Generally light snow should be tapering off during the day as
easterly up-slope flow along the eastern slope of the Colorado
Rockies eases and the left exit region of an upper level jet pulls
away...resulting in diminishing forcing for vertical motions in
the cold air mass. 


...Central Appalachians...

Days 1-2...
The reinforcing trough that was moving eastward across the central
Plains early this morning will reach the Ohio Valley on an
increasing jet streak later this afternoon.  Continental air is
lifted over the central Appalachians with snow levels generally
around 2000ft, dropping to 1000ft later tonight and early on
Wednesday morning.  Moderate snows are expected at these
elevations across the Allegheny Plateau in eastern WV and western
MD as well as the higher ridges east including the Blue Ridge in
central/northern VA...with lighter amounts extending northward
into Pennsylvania.

...Northern to Central Rockies and onto the Central Plains...

Days 2-3...
Another reinforcing trough drops south down the Canadian Rockies
and then across western MT later tonight and amplifies by the time
it reaches the northern Great Basin Thursday. Broad cyclonic flow
across the western U.S. with Pacific-sourced and eventually Gulf
of Mexico sourced moisture promotes snow across the northern
Rockies tonight and Wednesday. Day 1 snow probabilities for 6 or
more inches is high across western MT/northern ID and northwest
WY. These high probabilities spread to southern WY and northern CO
by Wednesday night/Thursday with probabilities moderately high for
6 or more inches spilling onto the Central High Plains of
southeast WY/northeast CO and across the NE Panhandle during the
day on Thursday.

For Days 1-3, the probability of significant icing (0.25 inch or
greater) is less than 10 percent.

Bann