SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
PRECIPITATION, GENERALLY SNOW OR A RAIN AND SNOW MIX WILL START TO
MOVE IN FROM THE SOUTHWEST DURING THE EVENING HOURS AS THE LEADING
TROUGH LIFTS INTO THE REGION. THE MAIN
UPPER LEVEL LOW WILL REMAIN
WELL WEST OF THE REGION THROUGH THIS TIME, SO DO NOT EXPECT THE
HEAVIEST SNOW TO BE THROUGH THE OVERNIGHT HOURS, AND THE MODELS HAVE
IN FACT TRENDED SLIGHTLY DRIER THROUGH THIS PERIOD. EVEN SO, THE
SOUTHERN HALF OF THE REGION COULD SEE AS MUCH AS 4 INCHES OF SNOW IF
MESOSCALE BANDS DEVELOP EARLY ENOUGH.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
THE SECONDARY COASTAL LOW THAT DEEPENS RAPIDLY OFF THE
NC OUTERBANKS
MONDAY NIGHT IS EXPECTED TO MOVE TOO FAR OFFSHORE ON TUESDAY TO
DIRECTLY IMPACT US. HOWEVER, WE AREN`T OUT OF THE WOODS AS MODELS
ARE SHOWING THE PRIMARY SURFACE LOW REORGANIZING AS IT MOVES OFF THE
DELMARVA COAST ON TUESDAY. THIS SEEMS LIKE A PLAUSIBLE SCENARIO
SINCE THE INITIAL MILLER-
B LOW IS EXPECTED TO MOVE WELL OUT TO
SEA (LEAVING SOME SEPARATION BETWEEN THE TWO) AND THERE LOOKS TO
BE ANOTHER MID-LEVEL
SHORTWAVE TROUGH ROTATING AROUND THE UPPER
LOW THAT WOULD CONTRIBUTE TO
HEIGHT FALLS AND COASTAL
CYCLOGENESIS. IN THESE TYPES OF SETUPS, ENHANCED FRONTOGENETICAL
LIFT AND
MESOSCALE BANDING IS FAVORED ON THE NWRN SIDE OF THE LOW.
THE 00Z GUIDANCE HAD COME INTO BETTER AGREEMENT AND SHOWS THE
POTENTIAL FOR
MESOSCALE BANDING IN THEIR MASS/
THERMAL FIELDS THAT
PRODUCES A RELATIVELY NARROW WEST-EAST ORIENTED BAND OF HEAVIER
QPF OVER THE NRN DELMARVA/SERN PA/
SRN NJ. PARTIAL THICKNESSES
IMPLY ALL SNOW. HOWEVER, THE CURRENT FORECAST OF HIGHS IN THE
UPPER 30S FOR THESE AREAS OF CONCERN IMPLY THE LOWER BOUNDARY
LAYER IS MARGINALLY SUPPORTIVE OF SNOW. THERE IS CERTAINLY A
POTENTIAL THAT SOME RAIN MIXES IN AND/OR SNOW HAS A TOUGH TIME
ACCUMULATING...BUT ONLY IF THE INTENSITY OF THE PRECIP IS LIGHT.
IF THE HEAVIER SNOW DOES MATERIALIZE, THEN DYNAMICAL COOLING
SHOULD BE ENOUGH TO OVERCOME THIS ISSUE.
AFTER COORDINATION WITH WPC AND NEIGHBORING WFOS, WE DECIDED IT WAS
BEST TO ISSUE A WINTER STORM
WATCH FOR FAR SERN PA, NRN DELMARVA AND
SRN NJ. THE WHOLE AREA IN THE
WATCH WILL
LIKELY NOT SEE
WARNING
CRITERIA SNOWFALL (AND SOME MAYBE SIGNIFICANTLY LESS) BUT THIS IS
WHERE THE GREATEST POTENTIAL FOR 5 OR MORE INCHES OF SNOWFALL
EXISTS IN A RATHER NARROW SWATH SOMEWHERE APPROXIMATELY AS FAR
NORTH AS PHILADELPHIA AND AS FAR SOUTH AS DOVER. ANOTHER
CHALLENGE WITH THIS EVENT IS TRYING TO PINPOINT THE TIMING OF THE
HEAVIER SNOW. THE
WATCH GOES STARTS LATE TONIGHT AND CONTINUES 28
HOURS THROUGH TUESDAY NIGHT. WE ARE NOT EXPECTING A LONG DURATION
EVENT BUT WE WENT WIDE IN TIME TO ACCOUNT FOR THE UNCERTAINTY IN
WHEN THE HEAVIER SNOW BAND DEVELOPS. ONE CAMP OF MODELS INDICATE
IT WILL OCCUR LATE TONIGHT INTO TUESDAY MORNING WHILE OTHER
CLUSTER FAVORS LATER TUESDAY AFTERNOON AND NIGHT.
FARTHER NORTH INTO NERN PA AND NWRN NJ, WHERE THE POSSIBILITY FOR
HEAVIER SNOW IS LOOKING LESS
LIKELY AT THIS POINT, LIGHT SNOW MAY
ONLY ACCUMULATE AN INCH OR TWO TUESDAY-TUESDAY NIGHT. HOWEVER,
WE`LL STILL NEED TO MONITOR FOR THE POSSIBILITY OF THE HEAVIER
SNOW BAND SHIFTING NORTHWARD. VERY FEW SCENARIOS CAN BE RULED OUT
AT THIS POINT.