Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
328 AM EST Thu Nov 26 2020

Valid 12Z Thu Nov 26 2020 - 12Z Sun Nov 29 2020

Days 1 to 3...

...Southwestern U.S...

An upper-level trough moving through the Southwest today through
Friday has an embedded wave that may close off into a mid level
low over AZ that will then move  east over New Mexico Sat and then
into the southern Plains.
Moisture circulating around the low into the ranges of northern AZ
to the ranges of New Mexico and adjacent southwest CO should
produce a few inches of snow each day. On Day 3, the precip in
most solutions starts as rain and changes over to snow in lower
elevations of eastern NM and the TX panhandle, so amounts will be
limited.  The primary uncertainty is the timing of the low, with
good clustering among the GFS/Canadian global/ECMWF/UKMET
solutions, with spread provided by the faster Nam and slower SREF
Mean.

...Northern New England...

Precipitation has occurred i conjunction with low-mid level warm
advection over sub-freezing surface cold air
over interior NH and southern Maine. The warm front and low level
warm advection pattern should continue to move north today,
producing widespread light precipitation.

Some light freezing rain (with locally up to near a 0.10" of ice
accretion) will be expected before a changeover to rain occurs
from south to north today (Thanksgiving Day) across interior
sections of Maine. The primary uncertainty is the rate of warming
as cold air retreats, with the NAM nest typically showing the
longer duration of subfreezing cold air.

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

Petersen