Right now, increasing confidence for accumulating snows Thursday Night. Cold front currently in the mid west moves across the region Wednesday Night. The low Thursday morning will likely be recorded at midnight in the 40's, with temperatures steady or falling through the day. Precipitation will stay in the form of rain through the evening. Front becomes anafrontal (precipitation behind the front) Thursday night, with temperatures falling to near 30, rain should change to snow around midnight. Entire column should support snow by Friday morning and some accumulation could occur.
That's the first story, which is really nice enough. There is more however. Trough digging to the southeast will create a vort max to the south of New England on Thursday. Much will depend on how far south this low develops. Models actually have an okay consensus on rapid deepening, however too late = too far north. The trend has been to the southwest, which is good for us (potential second round of snow Friday into early Saturday.
If good potential continues, first forecast will be issued tomorrow evening.
Also, if you'll notice, I've added mainly delay potential for Friday.
HPC HEAVY SNOW DISCUSSION
DAY 3...
A NEGATIVELY TILTED UPPER-LEVEL TROUGH OVER THE ERN CONUS WITH
SHORT WAVE DYNAMICS IN THE BASE OF THE UPPER TROUGH AXIS WILL
INDUCE A COASTAL LOW ALONG THE NERN SEABOARD. THIS SURFACE LOW
WILL DEEPEN TREMENDOUSLY OVER THE 24 HR FORECAST PERIOD AND USHER
A WAVE OF ATLANTIC MOISTURE INTO THE NEW ENGLAND AREA. NOW THE
OPERATIONAL MODEL GUIDANCE AND ENSEMBLES SHOW ENOUGH SPREAD ON THE
EXACT SURFACE LOW TRACK FROM CAPE COD NORTHWARD TOWARD NOVA SCOTIA
AND HOW CLOSE THIS LOW WILL BE TO THE COAST TO GREATLY IMPACT THE
DAY 3 FORECAST. THE ECMWF AND A GOOD NUMBER OF ENSEMBLE MEMBERS
HAVE THIS LOW TRACK ALONG THE IMMEDIATE COASTLINE... EVENTUALLY
STALLING ALONG COASTAL MAINE. THIS WOULD REALLY ALLOW QPF NUMBERS
TO PILE UP OVER THE 24 HR PERIOD BUT REALLY PROHIBIT RAIN CHANGING
OVER TO SNOW AS STRONG WAA FROM THE ATL WILL COUNTERACT THE COLD
POLAR AIR MASS SWEEPING THROUGH THE NERN CORRIDOR OF THE COUNTRY.
THE GFS AND ESPECIALLY NAM ARE JUST FAR ENOUGH OFF THE COAST WITH
THE DEEP CYCLONE THAT RAIN WOULD CHANGE OVER MUCH MORE QUICKLY
POSSIBLY LEADING TO HEAVY SNOWFALL IN THE DEFORMATION ZONE OVER
MAINE. THIS SMALL DIFFERENCE IN THE SURFACE LOW TRACK IS HUGE. HPC
FOLLOWED MOSTLY THE ECMWF SOLUTION WITH A HINT OF THE GFS FOR
SNOWFALL ACCUMULATIONS OF 4 TO 8 INCHES ACROSS WRN ME BUT IF THE
ECMWF IS CORRECT... THE SNOWFALL NUMBERS WOULD BE MUCH SMALLER AND
IF THE GFS IS CORRECT THE NUMBERS COULD EASILY DOUBLE ON FRI INTO
EARLY SAT MORNING.
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