Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 290737 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 337 AM EDT FRI MAY 29 2015 .SYNOPSIS... HIGH PRESSURE WILL REESTABLISH ITSELF OFF THE EAST COAST TODAY INTO SATURDAY. A COLD FRONT IS FORECAST TO MOVE ACROSS THE AREA SATURDAY NIGHT INTO SUNDAY, THEN STALL ACROSS OUR SOUTHERN AREAS OR JUST SOUTH OF THE AREA MONDAY INTO TUESDAY. HIGH PRESSURE WILL BUILD TO OUR NORTH EARLY NEXT WEEK, BEFORE TRYING TO NOSE ITS WAY INTO OUR AREA WEDNESDAY INTO THURSDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 3 AM THE COLD FRONT WAS THROUGH ALMOST ALL OF OUR REGION WITH THE EXCEPTION OF PORTIONS OF THE DELMARVA PENINSULA. WITH THE DRIER AIR IN THE WAKE OF THIS FRONT, SHOULD HAVE A COMFORTABLE DAY ON TAP WITH LOWER DEW POINTS THAN YESTERDAY AND HIGHS ONLY SLIGHTLY ABOVE NORMAL. MODELS CONTINUE TO SHOW SOME QPF, FIRST WITH LINGERING CONVECTION ALONG AND SOUTH OF THE FRONT THIS MORNING (WHICH SEEMS REASONABLE GIVEN HOW PERSISTENT SHOWERS HAVE BEEN IN NORTHEASTERN MD OVERNIGHT), AND THEN WITH AN AREA OF SHOWERS AND STORMS IN THE FAR WESTERN SECTIONS OF OUR CWA THIS AFTERNOON. THERE IS LIMITED SYNOPTIC SCALE LIFT, SO ANY CONVECTION IS UNLIKELY UNTIL THE BOUNDARY LAYER INVERSION DISSIPATES, WHICH IN THE WAKE OF THE COLD FRONT, MAY NOT HAPPEN UNTIL VERY LATE THIS AFTERNOON. ALL THAT BEING SAID, MADE FEW CHANGES TO THE POPS FROM THE PREVIOUS FORECAST. DID INCLUDE MENTION OF THUNDER, AS IT DOES APPEAR THERE IS ENOUGH INSTABILITY (IF THE INVERSION DISSIPATES) FOR THUNDERSTORMS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... THE NEXT COLD FRONT CONTINUES PROGRESS EAST OVER THE GREAT LAKES REGION, BUT STILL LOOKS TO STAY FAR ENOUGH WEST OF OUR REGION TO HAVE LIMITED IMPACT TONIGHT. WITH THE PERSISTENT SOUTHEASTERLY LOW LEVEL FLOW, COULD SEE FOG ALONG THE COASTAL WATERS. HOWEVER, THIS WILL BE DEPENDENT ON HOW MUCH MOIST AIR ADVECTION WILL OCCUR IN THE LATER HALF OF THE DAY, AS DEW POINTS WILL LIKELY START THE DAY IN THE 50S. && .LONG TERM /SATURDAY THROUGH THURSDAY/... THE SURFACE HIGH AND RIDGE ALOFT WILL GET PUSHED EASTWARD SATURDAY AHEAD OF AN APPROACHING COLD FRONT, WITH SOUTHWEST FLOW BOTH AT THE SURFACE AND ALOFT DEVELOPING. THIS WILL ALLOW FOR A COUPLE OF SHORT WAVE/VORTICITY IMPULSES TO MOVE ACROSS THE AREA LATE SATURDAY WHILE DAYTIME INSTABILITY DEVELOPS AS WELL. AN INCREASE IN SHOWER/THUNDERSTORM ACTIVITY IS POSSIBLE, ESPECIALLY FOR THE WESTERN PORTIONS OF THE AREA. THE COLD FRONT IS FORECAST TO MOVE INTO THE AREA SATURDAY NIGHT AND SLOWLY MOVE ACROSS THE AREA INTO SUNDAY. THE GFS AND ECMWF HAVE PRETTY GOOD AGREEMENT WITH THE TIMING OF THE PRECIPITATION. BOTH AGREE THAT SUNDAY LOOKS TO BE THE PERIOD WITH HIGHEST PROBABILITY FOR PRECIPITATION AS THE FRONT MOVES ACROSS AND SOUTH OF THE AREA. PW VALUES INCREASE TO NEAR 2 INCHES, SO THERE COULD BE A PERIOD OF HEAVY RAINFALL WITH ANY SHOWERS THAT DEVELOP DURING THE TIME PERIOD. THERE REMAINS INSTABILITY FORECAST AHEAD OF THE FRONT, SO WE WILL KEEP THUNDERSTORMS IN THE FORECAST, BUT ONCE THE FRONT PASSES, THUNDERSTORM POTENTIAL DECREASES. HIGH PRESSURE RETURNS TO OUR NORTHEAST EARLY NEXT WEEK AS THE FRONTAL BOUNDARY PUSHES SOUTH AND LIKELY STALLS JUST SOUTH OF OUR AREA. WITH THE HIGH TO OUR NORTHEAST, THIS WILL KEEP EASTERLY FLOW ACROSS THE AREA. SOUTHWEST-WESTERLY FLOW ALOFT WILL REMAIN ACROSS THE AREA AS WELL. SEVERAL SHORT WAVE/VORTICITY IMPULSES WILL LIKELY MOVE ACROSS THE AREA EARLY NEXT WEEK, WHICH COULD HELP CREATE PRECIPITATION ACROSS THE AREA. IT IS LOOKING LIKE WE COULD HAVE A PERIOD WITH GOOD SOAKING RAINS, JUST HOPEFULLY IT DOES NOT COME TOO QUICKLY. WITH THE EASTERLY FLOW ACROSS THE AREA, THE ATMOSPHERE SHOULD BE STABLE, SO WE KEEP THUNDERSTORMS OUT OF THE FORECAST MONDAY AND TUESDAY DUE TO LACK OF INSTABILITY. THE HIGH PRESSURE ACROSS THE NORTHEAST SHOULD BUILD SOUTH ACROSS THE AREA WEDNESDAY INTO THURSDAY, STARTING ANOTHER DRY PERIOD. && .AVIATION /07Z FRIDAY THROUGH TUESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. MOSTLY VFR CONDITIONS FOR THE TAF PERIOD. THE COLD FRONT IS NOW SOUTH OF ALL THE TAF SITES, AND DRIER AIR IS CONTINUES TO ADVECT OVER THE REGION. THERE IS ALSO A SMALL POSSIBILITY OF FOG AND LOW STRATUS DEVELOPING AFTER 03Z TONIGHT ACROSS MUCH OF THE REGION AS DEPICTED IN TIME HEIGHT DISPLAYS OF BOTH THE GFS AND NAM. HOWEVER, MODELS APPEAR TO BE UNDERESTIMATING THE AMOUNT OF DRY AIR ADVECTION CURRENTLY, SO DESPITE EASTERLY/SOUTHEASTERLY WINDS FOR MUCH OF THE PERIOD, CONDITIONS BELOW VFR SEEM UNLIKELY FOR KPHL, KABE, KRDG, KTTN, AND KPNE. AT KILG, KMIV, AND KACY WHERE THE MARINE LAYER IS MORE LIKELY TO ADVECT IN, LOW STRATUS (AROUND 2000 TO 3000 FT AGL) IS POSSIBLE. WINDS WILL SLOWLY SHIFT FROM NORTHEASTERLY NOW, TO EASTERLY BY 15Z, TO SOUTHEASTERLY AFTER 18Z. HOWEVER, WIND SPEEDS ARE EXPECTED TO STAY AROUND OR BELOW 10KT. OUTLOOK... SATURDAY...LOWER CONDITIONS POSSIBLE EARLY, THEN BECOMING VFR DURING THE DAY. SCATTERED SHOWERS AND THUNDERSTORMS POSSIBLE WHICH MAY LOCALLY REDUCE CIGS/VSBYS. GUSTY SOUTH-SOUTHWEST WINDS AROUND 20 KNOTS. SATURDAY NIGHT-TUESDAY...AN EXTENDED PERIOD OF MVFR/IFR CONDITIONS POSSIBLE. A CHANCE OF RAIN EACH DAY. BEST POTENTIAL FOR THUNDERSTORMS IS SUNDAY AS A COLD FRONT MOVES THROUGH THE AREA. WIND BECOME NORTHEAST BEHIND THE FRONT AND CONTINUE THROUGH TUESDAY. WINDS COULD GUST TO 20 KNOTS AT TIMES SUNDAY NIGHT THROUGH TUESDAY. && .MARINE... WINDS AND SEAS SHOULD REMAIN BELOW SMALL CRAFT CRITERIA TODAY AND TONIGHT. THERE MAY BE SOME GUSTY WINDS IN THE VICINITY OF THUNDERSTORMS THROUGH ABOUT MID DAY. OUTLOOK... SATURDAY-TUESDAY...SEAS MAY RETURN TO 5 FEET OR GREATER LATE ON SATURDAY AHEAD AHEAD OF AN APPROACHING COLD FRONT. SEAS MAY REMAIN ELEVATED INTO TUESDAY, AND WINDS MAY INCREASE TO 25 KNOTS MONDAY INTO TUESDAY. && .RIP CURRENTS... NEW WEBLINK, WORKS BEST ON FIREFOX. DISPLAYS THE FCST GRAPHIC ETC. WWW.WEATHER.GOV/PHI/SURFRIP4 LOW RISK CONTINUES THROUGH FRIDAY. SUBSTANTIAL UPWELLING OCCURRED YESTERDAY WITH THE SOUTHERLY FLOW, ESPECIALLY NNJ WATERS WHERE 44065 WATER TEMP DROPPED ALMOST 9 DEGREES IN 24 HRS DOWN INTO THE UPPER 40S EARLIER THIS MORNING. CHILLY TO SWIM MOST OF CENTRAL AND NNJ BEACHES DESPITE WELL ABOVE NORMAL LAND TEMPS. && .CLIMATE... MAY 2015...A TOP 5 WARMEST ON RECORD FOR LARGE PORTIONS OF OUR AREA. CONSERVATIVE VALUES LISTED BELOW FROM OUR 5 AM SFT AND COOLING THE NEAR MIDNIGHT SUNDAY NIGHT MAY 31 LOW TEMP DUE TO NLY FLOW CAA SUNDAY EVENING. ALLENTOWN WILL PROBABLY AVERAGE VERY CLOSE TO 65.9 OR 6 DEGREES ABOVE NORMAL. POR BACK TO 1922. AT LEAST 5TH WARMEST ON RECORD. 1991 67.2 2012 66.1 1944 66.0 2004 65.9 PHILADELPHIA WILL PROBABLY AVERAGE CLOSE TO 69.7 DEGREES OR 5.8 DEGREES ABOVE NORMAL. SECOND WARMEST ON RECORD. 1991 70.8 NUMBER 3 WOULD BE 69.2 IN 2004. ATLANTIC CITY MAY 2015 65.9 OR 4.8 ABOVE NORMAL AND PROBABLE #3 POR BACK TO 1874 2004 66.9 1991 66.0 2015 WILMINGTON DE SOLID POR BACK TO 1916 LOCKED INTO #4 WARMEST 1896 70.1 1991 69.1 2004 68.2 2015 NO AVAILABLE MONTHLY HISTORICAL DATA FOR KMPO KGED KTTN AND KRDG. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...ROBERTSON NEAR TERM...JOHNSON SHORT TERM...JOHNSON LONG TERM...ROBERTSON AVIATION...JOHNSON/ROBERTSON MARINE...DRAG/JOHNSON/ROBERTSON RIP CURRENTS...DRAG CLIMATE...

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