Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
422 AM EDT Fri Apr 02 2021

Valid 12Z Fri Apr 02 2021 - 12Z Mon Apr 05 2021


Days 1 into 2...
The probability of significant icing and/or snow is less than 10
percent.

Pacific Northwest...
Days 2/3...

Low pressure over the eastern Gulf of Alaska this morning ejects
southeast down the AK/BC coast through Saturday night before
shifting inland over WA on Sunday. Uncertainty with this low track
over the weekend continues to be rather high with the 00Z GFS the
greatest outlier and west of the 00Z GEFSmean along with the 00Z
NAM/ECMWF/UKMET/CMC which together make a cluster of decent
confidence. Pacific moisture spreading inland over WA on Saturday
ahead of the trough allows some potential for moderate to locally
heavy snow, particularly in the northern Rockies Sunday night as
currently indicated by the 00Z ECMWF. This upper low track
warrants further monitoring.


New England
Day 3...

A reinforcing shortwave trough rounding the main low over the
Northeast will swing off the NC coast this morning and eventually
break off into is own low well off the New England coast on
Saturday as the parent low ejects north. This breakaway low then
likely retrogrades west toward eastern Maine Sunday night. There
is considerable uncertainty with this motion, but a solution like
the 00Z ECMWF/GFS/UKMET would put the low close enough to eastern
Maine to allow wrap around snow to cover much of Maine by Sunday
night. While heavy snow is not anticipated at this time, it is
worth monitoring the progress of this low.


The probability of significant icing is less than 10 percent.


Jackson