From NWS Mt. Holly, NJ (Phila. area)
.LONG TERM /SATURDAY THROUGH TUESDAY/...
THE FOCUS OF THE LONG TERM PORTION OF THE FORECAST CONTINUES TO
BE THE DEVELOPING WINTER STORM FOR FRIDAY NIGHT AND SATURDAY. THE
12Z GFS AND ECMWF HAVE COME INTO AGREEMENT ON SURFACE LOW PRESSURE
TIMING AND STRENGTH, AS WELL AS THE EVOLUTION OF UPPER AIR
PROGRESSION. THE UPPER TROUGH DRIVING EASTWARD FROM THE
SOUTHWESTERN STATES IS SEEN TO PHASE WITH THE CLOSED LOW INITIALLY
IN THE HIGH PLAINS, AND THIS LATTER FEATURE DIGS TO THE OHIO
VALLEY AND TO THE MID ATLANTIC COAST FRIDAY AND FRIDAY NIGHT,
WHICH WILL CAUSE STRONG INTENSIFICATION OF THE SURFACE LOW MOVING
OUT OF THE DEEP SOUTH AND NORTHEASTWARD TO OFF THE NORTH CAROLINA
COAST BY EARLY SATURDAY MORNING. INTRA-MODEL CONSISTENCY WITH
PRIOR RUNS, AND 12Z GFS AND ECMWF AGREEMENT, BOOST CONFIDENCE IN
THE POTENTIAL FOR A STRONG EVENT IN OUR AREA. PROBABILITIES WERE
INCREASED FOR THIS FORECAST TO CATEGORICAL AND LIKELY SOUTH AND
CENTRAL, AND TO CHANCE NORTH FOR FRIDAY NIGHT INTO SATURDAY. WITH
1000-500 HPA THICKNESSES MOSTLY BELOW 540 DM AND 1000-850 HPA
THICKNESSES MOSTLY BELOW 1300 M, MOSTLY SNOW WAS FORECAST. THE
EXCEPTION WAS A MIX OF SNOW AND RAIN FOR THE FAR SOUTH LAND AND
SOUTHEAST MARINE AREAS. QUANTITATIVE PRECIPITATION IS EXPECTED TO
BE MODERATE TO HEAVY WITH SUCH STORM STRENGTH AND TRACK. ALSO, IT
SHOULD BE A WINDY STORM. SO, A COMBINATION OF WEATHER PARAMETERS
MAY HAVE SIGNIFICANT EFFECTS IN OUR AREA FRIDAY NIGHT AND
SATURDAY.