Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
423 AM EST Thu Nov 21 2019

Valid 12Z Thu Nov 21 2019 - 12Z Sun Nov 24 2019


Days 1-3...

...Southwest/Great Basin/Central and Southern Rockies...
An upper low will continue to support mountain snows as it drifts
east from California into the Great Basin/Southwest on Thursday. 
Heaviest amounts on Thursday are expected to fall across the
central Colorado and northern New Mexico ranges, where deep
southwesterly inflow along with left-exit region upper jet forcing
is helping to support higher probabilities for additional
accumulations of 8-inches or more. 

As the low moves east into the Plains, expect snows to diminish
from west to east across the region by late Thursday.

...Great Lakes/Northeast...
Low pressure over the Mississippi valley will track northeast
across the upper Great Lakes on Friday.  Ahead of the low,
right-entrance region upper jet forcing along with low-to-mid
level frontogenesis is expected to enhance precipitation rates
with rain changing to snow across northern Wisconsin and the
eastern U.P. of Michigan Thursday morning.  Then as the low slides
off to east, northerly flow in its wake will likely support
lake-enhanced snow showers - further bolstering the potential for
locally heavier totals over the eastern U.P. 

As the low continues to track east across Ontario, a period of
snow may result in a few inches of snow across northern Maine
before precipitation changes to rain Friday morning.

The probability of significant icing (0.25-inch) is less than 10
percent.

Pereira