Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
327 PM EDT Sat Apr 06 2019

Valid 00Z Sun Apr 07 2019 - 00Z Wed Apr 10 2019


...Pacific Northwest to the Northern Rockies...

Mid level energy and deep moisture embedded within progressive
southwesterly flow is expected to support widespread precipitation
across the region Saturday evening into Sunday.  However with snow
levels increasing on Sunday, widespread heavy snow accumulations
are not expected.  Flat shortwave ridging will keep snow levels
high through Monday.  Then by early Tuesday, models show a
well-defined trough moving inland and amplifying over the West. 
Models show moderate to heavy snow developing initially over the
central Idaho and southwestern Montana ranges before extending
farther to the east into northwestern Wyoming as upslope increases
on the west side of a developing surface cyclone.

...Northeast...

Strong low level theta-e advection into a region of confluent flow
aloft and surface high pressure is expected to support mixed
precipitation developing across northern Vermont and New Hampshire
on Tuesday, with primarily snow farther to the east across
northern Maine.  As low pressure sliding south of the region and
then off the coast helps to maintain the cold air, significant
snow accumulations are expected across northern Maine.  For the
24-hr period ending 00Z Tue, WPC probabilities indicate a Slight
Risk or greater for accumulations of 8-inches or more across much
of central and northern Maine. 

Pereira