Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 111946 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 346 PM EDT FRI APR 11 2014 .SYNOPSIS... A COLD FRONTAL BOUNDARY WILL MOVE THOUGH THE REGION TONIGHT. THIS WILL BE FOLLOWED BY A HIGH PRESSURE SYSTEM BUILDING INTO THE REGION AND THE BOUNDARY LIFTING NORTH AS A WARM FRONT DURING THE WEEKEND. ANOTHER COLD FRONTAL BOUNDARY WILL APPROACH THE REGION BY TUESDAY WITH SEVERAL WAVES OF LOW PRESSURE TRAVELING ALONG THE FRONT. THIS WILL GIVE WAY TO ANOTHER HIGH PRESSURE SYSTEM FOR THE MIDDLE AND LATER HALF OF THE WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... ANOTHER BEAUTIFUL DAY HAS OCCURRED OVER MOST OF THE AREA, WITH THE EXCEPTION OF THE NW, WHERE THERE HAVE BEEN SOME RAIN SHOWERS, BUT TEMPERATURES HAVE SKYROCKETED TODAY WELL INTO THE 70S IN MANY AREAS ON STRONG SWLY FLOW. A WEAK CDFNT IS SLOWLY WORKING ITS WAY SEWD AND WILL CROSS THE REGION THIS EVENING AND OVERNIGHT. WITH THE FRONT THERE WILL BE SOME RAIN SHOWERS, BEFORE THE WIND SHIFTS TO NW BRING IN IN DRIER AIR AND ENDING THE PRECIP. FOR AREAS FROM THE I-95 CORRIDOR S AND E, THE MAJORITY OF THE RNFL WILL BE AFTER 00Z, AND PRECIP CHCS SHOULD BE ENDING BY MIDNIGHT OR SO. && .SHORT TERM /6 AM SATURDAY THROUGH 6 AM SATURDAY/... HIGH PRESSURE WILL BUILD BACK IN FOR SAT AND EXPECT ANOTHER GREAT DAY, WITH TEMPS INTO THE 70S IN MANY AREAS AND ABUNDANT SUNSHINE. && .LONG TERM /SATURDAY THROUGH FRIDAY/... SATURDAY NIGHT THROUGH MONDAY: HIGH PRESSURE WILL BE GRADUALLY SLIDING OFF TO OUR NORTHEAST WHICH MEANS AN EXTENDED PERIOD OF SOUTHERLY TO SOUTHWESTERLY FLOW, WAA. 850 MB TEMPS WILL RISE TO BETWEEN +10 AND +14C BY SUNDAY AND MONDAY COUPLED WITH FULL SUNSHINE MANY OF US SHOULD BE WELL INTO THE 70`S. FORECAST TEMPERATURES AT OR A JUST A TOUCH WARMER THAN MAV/MET GUIDANCE AND MUCH WARMER THAN TWO METER TEMPERATURES GIVEN THE SET-UP. HIGH CONFIDENCE FROM THE OPERATIONAL MODEL RUNS AND THE ENSEMBLE SPREAD THAT THE MAIN IMPACTS FROM THE NEXT COLD FRONTAL SYSTEM WILL HOLD OFF TILL AFTER THIS PERIOD. THE ONE DRAWBACK MAY BE A TIGHT DEWPOINT/TEMPERATURE DEPRESSION FOR A FEW HOURS AROUND SUNRISE SUNDAY LEADING TO THE POTENTIAL OF A PERIOD OF LOW CLOUDS AND/OR FOG. ANY LOW CLOUDS OR FOG SHOULD QUICKLY BURN OFF BY MID MORNING. MONDAY NIGHT THROUGH TUESDAY NIGHT: A FAIRLY VIGOROUS COLD FRONT BOUNDARY WITH SEVERAL WAVES OF LOW PRESSURE WILL MOVE INTO THE REGION DURING THIS TIMEFRAME. WILL GRADUALLY INCREASE RAIN CHANCES MONDAY NIGHT INTO TUESDAY THEN DECREASE RAIN CHANCES TUESDAY NIGHT. PW VALUES WILL INCREASE TO AROUND 1.5 INCHES RESULTING IN THE THREAT FOR HEAVY RAINFALL. A GOOD MODEL CONSENSUS ATTM BETWEEN THE GFS, CMC AND ECMWF OF RAINFALL BETWEEN ONE AND TWO INCHES FROM THIS SYSTEM. TEMPERATURES WILL BE QUITE WARM MONDAY NIGHT AHEAD OF THE FRONT AS WELL, WENT WARMER WITH THE OVERNIGHT LOWS GIVEN THE SOUTHERLY FLOW/LLJ AND COOLER ON TUESDAY HIGHS GIVEN THE CLOUDS AND RAINFALL. INSTABILITY WILL BE NON EXISTENT LEADING TO A LOW OR NEGLIGIBLE THUNDER THREAT. TEMPERATURES WILL BECOME MARGINAL FOR MIXED PRECIPITATION AS WELL TUESDAY NIGHT AFTER THE FRONTAL PASSAGE NW OF PHL. I`M NOT SOLD ON THE AMOUNT OF POST-FRONTAL PRECIPITATION SHOWN ON THE ECMWF RECENTLY INCLUDING THE NEW 12Z RUN. THINKING A MORE PROGRESSIVE PASSAGE WILL LIMIT THE OPPORTUNITY FOR MIXED PRECIPITATION BUT STILL DO HAVE A FEW HOUR WINDOW FOR SNOW IN THE GRIDS. WEDNESDAY THROUGH FRIDAY: SOME CLOUDS AND PERHAPS A RAIN/SNOW SHOWER MAY LINGER FOR WEDNESDAY MORNING. OTHERWISE A FAIRLY STRONG SIGNAL THAT HIGH PRESSURE WILL BE A DOMINANT FEATURE IN THE REGION DURING THIS PERIOD. MUCH COOLER AS THE FLOW TO PREDOMINATELY NORTH/NORTHEAST. SOME PATCHY FROST IS POSSIBLE THURSDAY MORNING IN PARTS OF THE REGION WHERE THE GROWING SEASON ENDS ON APRIL 15TH AWAY FROM THE DELMARVA, METRO PHILLY AND COASTAL NJ. HOWEVER WINDS MAY BE JUST STRONG ENOUGH TO PREVENT WIDESPREAD FROST FORMATION. THE NEW 12Z ECMWF ADDED IN SEVERAL WRINKLES WITH A LOW PRESSURE SYSTEM MOVING UP THE COAST EARLY THURSDAY, THE 12Z GFS SPUN UP A LOW FOR FRIDAY. FOR NOW OPTED NOT TO INCLUDE ANY LOW PRESSURE SYSTEM IMPACT THE REGION IN THIS PERIOD GIVEN VERY LIMITED SUPPORT FROM THE MORNING ENSEMBLES WHICH IS IN LINE WITH WPC. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDS WILL PREVAIL FOR ALL OR MOST OF THE TAF PD. A WK CDFNT IS WORKING ITS WAY SEWD THRU THE REGION. THERE HAS BEEN SOME LIGHT SHRA INVOF KABE MOST OF THE DAY BUT IT HAS BEEN LIGHT ENOUGH TO MAINTAIN VFR CONDS. AS THE FRONT MOVES SEWD THRU THE LATE AFTN AND EVE, PRECIP CHCS WILL INCREASE. THERE COULD BE SOME MVFR CONDS, BUT CONFIDENCE IS LOW. ONCE THE FRONT MOVES THRU, GENLY BY MIDNIGHT EVERYWHERE, THEN A RETURN TO VFR CONDS AND ANOTHER NICE DAY IS IN STORE FOR SAT. SWLY WIND WILL PREVAIL AHEAD OF THE CFP. THE WIND WILL BECOME MORE WLY AND EVENTUALLY NWLY BEHIND THE FRONT. THE CFP NW WIND WILL ALSO BRING IN DRIER AIR WHICH WILL END ANY PRECIP AND HELP RETURN ANY CONDS THAT ARE LWR TO VFR. OUTLOOK... SATURDAY NIGHT: MAINLY VFR SOME POTENTIAL FOR A BRIEF PERIOD OF FOG/OVERCAST AROUND SUNRISE SUNDAY WITH RESTRICTIONS TO MVFR. SUNDAY: ANY MVFR FOG/STRATUS QUICKLY BURNING OFF BY MID-MORNING, OTHERWISE VFR. SOUTH WINDS 10-15 KNOTS WITH GUSTS TO 20 KNOTS. SUNDAY NIGHT AND MONDAY: VFR SOUTH WINDS 10-15 KNOTS WITH GUSTS TO 25 KNOTS. MONDAY NIGHT: CONDITIONS DETERIORATING TO MVFR/IFR MONDAY NIGHT WITH RAIN DEVELOPING SOUTH WINDS 10-15 KNOTS. HIGHER GUSTS TO 20 KNOTS. TUESDAY AND TUESDAY NIGHT: MVFR/IFR IN RAIN. WET SNOW MAY MIX IN NORTHWEST OF ABE LATE TUESDAY NIGHT. SOUTH WIND 10-15 KNOTS SHIFTING TO NORTHWEST BY TUESDAY NIGHT AROUND 10 KNOTS. A FEW HIGHER GUSTS TO 20 KNOTS. WEDNESDAY: IMPROVING CONDITIONS TO VFR WITH DECREASING CLOUDS BY MIDDAY. && .MARINE... WILL EXTEND THE SCA THRU 06Z UNTIL THE FRONT HAS CLEARED THE COAST. IT MAY BE QUITE MARGINAL, BUT WOULD WANT TO SEE WHAT IMPACT THE FRONT HAS BEFORE DROPPING ANY HEADLINES. WW IS CURRENTLY ABOUT A FOOT TOO HIGH AS IS OFTEN THE CASE ON SWLY FLOW. ONCE THE FRONT CLEARS THE AREA, HIGH PRES WILL BUILD IN AND NO FURTHER MARINE HEADLINES ARE ANTICIPATED THRU THE NEAR AND SHORT TERM PDS. OUTLOOK... SATURDAY NIGHT AND SUNDAY: SEAS BUILDING TO FIVE FEET BY SUNDAY EVENING WITH SOME SOUTHERLY SCA GUSTS BY SUNDAY AFTERNOON. SUNDAY NIGHT THROUGH WEDNESDAY: SEAS AND WINDS EXCEEDING SCA CRITERIA. WINDS AND SEAS MAY WEAKEN BELOW SCA CRITERIA BY WEDNESDAY. SOUTHERLY GUSTS THROUGH TUESDAY AHEAD OF THE FRONT SHIFTING TO NORTHWEST BEHIND THE FRONT. && .CLIMATE... HERE ARE THE DATES OF THE LAST 70 DEGREE TEMPERATURE READINGS AT EACH OF THE FOLLOWING LOCATIONS NOT COUNTING TODAY. ALLENTOWN PA - NOVEMBER 1. READING PA - NOVEMBER 1. TRENTON NJ - NOVEMBER 1. PHILADELPHIA PA - NOVEMBER 2. WILMINGTON DE - DECEMBER 22. ATLANTIC CITY NJ - DECEMBER 22. GEORGETOWN DE - MARCH 22. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT SATURDAY FOR ANZ450>455. && $$ SYNOPSIS...GAINES NEAR TERM...NIERENBERG SHORT TERM...NIERENBERG LONG TERM...GAINES AVIATION...GAINES/NIERENBERG MARINE...GAINES/NIERENBERG CLIMATE...

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