Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
256 PM EST Mon Nov 06 2023

Valid 00Z Tue Nov 07 2023 - 00Z Fri Nov 10 2023

...Northwest, California through the Northern Rockies and then
Colorado...
Days 1-2...
Unsettled weather, including mountain snow, will continue for
another day across the Cascades, Sierra, and the northern Rockies
as a broad positively-tilted upper trough moves across the West. 
While widespread heavy snowfall amounts are not expected, many of
the region's passes may be impacted, with WPC guidance indicating
that additional accumulations of 2-4 inches are likely, with
locally heavier amounts possible.  Snow will begin to diminish
from west to east across the region late Tuesday and Wednesday as
the trough moves east, replaced by a building ridge along the
Northwest coast. 

Meanwhile, energy embedded within the base of the trough will
produce some mainly light high-elevation snow across the Great
Basin on Tuesday, before spreading into the southern Wyoming and
Colorado ranges.  But there too, amounts are forecast to remain
light, with WPC probabilities not indicating any significant
chance for widespread heavy accumulations.


Northern Plains, Northern Great Lakes, Northeast...
Days 1-3...
Warm advection precipitation will spread out across North Dakota
ahead of the wave moving out of the northern Rockies.  Some mixed
precipitation, including freezing rain, is possible Tuesday
morning, with the highest probabilities for accumulating ice (0.01
inch or more) centered across north-central North Dakota.

Some light precipitation, with mostly limited winter weather
impacts is forecast to shift farther east into the northern Great
Lakes region early Wednesday. 

Meanwhile, as the trough in the West continues to advance, surface
low pressure developing over the central High Plains late Tuesday
will advance northeast into the mid Mississippi Valley on
Wednesday.  Increasing moisture and ascent will support a
broadening precipitation shield ahead of the advancing low,
however thermal profiles suggest mostly rain for the region, apart
from some wet snowflakes across the northern U.P. of Michigan.

Cold high pressure over the Northeast will give way to the
advancing low, with precipitation spreading across the Northeast
late Wednesday into Thursday.  Following a brief period of snow at
the onset, warming air aloft will support a wintry mix across
portions of eastern Upstate New York into central and northern New
England before ending as rain across most areas.  Higher
probabilities for accumulating ice (0.01 inch or more) are mostly
centered across the higher terrain, including the Catskills,
Adirondacks, Berkshires, and Greens.

Pereira