Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
404 PM EDT Sun Mar 17 2019

Valid 00Z Mon Mar 18 2019 - 00Z Thu Mar 21 2019


...CO/NM Mountains/High Plains Days 2-3...
Upslope flow combines with a brief period of enhanced moisture and
lift in conjunction with a passing 700 mb shortwave is expected to
support some accumulating snows along the Colorado Front Range,
Sangre de Cristos, and San Juans on day 2, sinking into the NM
Sangre DeCristos Day 3. WPC probabilities indicating a Slight Risk
for accumulations of 4 inches in CO during day 2 and in NM in the
Day 3 Period.

...Ca Sierra Nevada Day 3...
On day 3 Tue night-Wed, a negatively-tilted upper trough will push
into California Tuesday night into Wednesday, with the upper jet
maxima crossing southern CA and northern Mexico placing the
difluent flow aloft with favorable upper divergence crossing much
of the Sierra this period.  With lift aided by orography, an
extended period of snow is expected for the Sierra.
 
WPC probabilities show a high Risk for accumulations of 4 inches
or more for areas above 7000 ft and low to moderate risk for 8
inches during the Day 3 period Tue night-Wed.

...Central Appalachians /upper Ohio Valley/Mid Atlantic Day 1...
A band of snow north of of a weak low pressure center in the Ohio
Valley is expected to continue downstream into the central
Appalachians, with the band weakening as it crosses the mountains
as low pressure weakens, with low level convergence waning as a
result.The primary area of accumulating snow is centered in the
mountains of central to northern West Va with lighter amounts in
southeast Ohio to northern MD, with the precip type limiting
accumulations in central to southern MD and the Delmarva.

The probability of significant freezing rain is less than 10
percent days 1-3.

Petersen