Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
449 PM EST Mon Feb 10 2020

Valid 00Z Tue Feb 11 2020 - 00Z Fri Feb 14 2020

...Southern California across the the southern Rockies and the
southern High Plains...

Days 1-2...
A closed low over the northern Baja this afternoon will weaken as
it shifts eastward into northwest Mexico and adjacent portions of
southern Arizona and New Mexico on Tuesday.  Any on-going winter
weather at the start of the Day 1 period over the southern
California mountains should be coming to a close rather quickly as
the system pulls away.

Farther east, southwesterly flow ahead of the low will support
expanding precipitation spreading across southern and central AZ
and NM, with high elevation snows expected along the Mogollon Rim
and White Mountains through tonight. Meanwhile, enhanced low level
convergence/frontogenesis associated with the northern stream wave
will support locally heavy snows moving south through the southern
Colorado to the northern New Mexico ranges tonight into Tuesday.
By early Tuesday, deepening moisture east of the Rockies will
begin to interact with the low-to-mid level baroclinic zone
dropping into the TX Panhandle supporting snows spreading east,
with the potential for significant amounts developing across the
region on Tuesday before the system finally moves out of the
region.

...Midwest and Northeast...

Day 3...
Remnant southern stream energy lifts northeast and into the
northern stream trough over the Midwest Wednesday. A powerful
southwesterly jet forms ahead of the northern stream trough with
precip spreading across the Upper Midwest/Northeast through
Wednesday night. At the same time, a polar cold front initially
over southern Canada will sweep into the Upper Midwest and
northern Great Lakes region which allows enhancement of the low as
it tracks over the Northeast states. The north side of the precip
shield is cold enough for snow and a warm nose could allow light
icing particularly over PA/NY/far western MA Wednesday night and
early Thursday. Currently the risk for 4 inches or more is quite
low with the exception of the UP in the wake of the polar
front...where the trajectory of cold air across an open Lake
Superior leads to probabilities in the 20 to 30 percent range.

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

Bann