Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 291608 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1208 PM EDT FRI MAY 29 2015 .SYNOPSIS... HIGH PRESSURE BUILDS OFF THE NORTH ATLANTIC COAST TODAY INTO SATURDAY. A COLD FRONT IS FORECAST TO MOVE SLOWLY SOUTHEAST ACROSS THE AREA LATE SATURDAY NIGHT THROUGH 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/... 930 AM ESTF: A VERY NICE DAY IN PROGRESS MOST OF THE FORECAST AREA WITH REMAINING HUMIDITY, CLOUDS, ML CAPE AND POTENTIAL FOR HEAVY SHOWERS ISOLATED TSTMS CONFINED MAINLY TO THE DELMARVA. DEWPOINTS ABOUT 15F LOWER IN PORTIONS OF EASTERN PA AND NJ COMPARED TO THIS TIME YDY. AS OF 9 AM THIS MORNING, THE 12Z HRRR FCST REDEVELOPMENT OF HEAVY CONVECTION BETWEEN 17Z AND 19Z FOCUSED ON QUEEN ANNES, CAROLINE AND TALBOT COUNTIES IN MD POSSIBLY WITH ITS RAINFALL CANOPY LEAKING NORTH AND EASTWARD INTO KENT COUNTIES OF MD AND DE AS WELL AS WESTERN SUSSEX COUNTY DE. THE 12Z NAM SUGGESTS SIMILAR BUT IS DEVELOPING MID AFTERNOON. CONFIDENCE: BELOW AVERAGE FOR THIS REDEVELOPMENT BUT HAVE BOOSTED POPS TO AROUND 40 PCT THERE AND LOWERED POPS IN E PA, S NJ, COASTAL DE WHERE ITS VERY DIFFICULT TO SEE ANY RAIN LATE TODAY. DID RAISE TEMPS 1-2 DEGREES FROM THE CURRENT FCST AWAY FROM THE COAST. OTRW, LITTLE CHANGE TO THE PREVIOUS FORECAST. FWIW, THE 12Z/28 NAM WAS TERRIBLE IN ITS RH TSECTION DEPICTION FOR THIS PAST NIGHT. && .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 /16Z FRIDAY THROUGH TUESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND TODAY...VFR WITH SCT CLOUDS AOA 5000 FT. LIGHT NE-E WIND BECOMING SE TO S THIS AFTERNOON. TONIGHT...VFR TO START. LIGHT SOUTH WIND. THERE IS 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. 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 WILL REMAIN BELOW SMALL CRAFT CRITERIA TODAY AND TONIGHT. 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 UPGRADED THE RIP CURRENT RISK ALONG THE CENTRAL NJ COAST PER OBSERVED CONCERN AND SOME DATA INDICATING POTENTIAL FOR MODERATE. OTHERWISE, LOW RISK CONTINUES THIS AFTERNOON DELAWARE COAST AND THE FAR NORTHERN AND FAR SOUTHERN NJ COASTS WHERE ONSHORE WINDS ARE LIGHTER THOUGH A LITTLE CONCERNED ABOUT A 1 FOOT 12 SECOND ESE SWELL SHOWING UP THAT COULD ELEVATE THE RISK SLIGHTLY THERE TOO. CHILLY TO SWIM MOST OF CENTRAL AND NNJ BEACHES DESPITE ABOVE NORMAL TEMPS ON THE LAND WITH WATER TEMPS THERE LOOKING TO BE IN THE UPPER 40S TO LOWER 50S. FURTHER S NEAR LBI...WATER TEMPS MAYBE 55 TO 60, SNJ S OF KACY 60-65 AND THEN ALONG THE DE ATLC COAST UPPER 50S TO MID 60S DEPENDING ON LOCATION. THE OUTLOOK FOR SATURDAY IS LOW ENHANCED...WITH A STRONGER SOUTHERLY WIND GUSTING TO 20 MPH DURING THE AFTERNOON. MIGHT BE A CLOSE CALL FOR A MODERATE RISK DEPENDING ON THE SWELL SIZE. FOR NOW KEEPING IT LOW RISK BUT NOT LOCKED INTO LOW. && .CLIMATE... MAY 2015...A TOP 5 WARMEST ON RECORD FOR LARGE PORTIONS OF OUR AREA. ALL OVERNIGHT AND FORECAST INFORMATION CHECKED THROUGH 830 AM TODAY - FRIDAY MAY 29. 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 66.0 OR 4.8 TO 4.9 ABOVE NORMAL AND PROBABLE #2 OR #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 AROUND 68.0 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...DRAG/JOHNSON SHORT TERM...JOHNSON LONG TERM...ROBERTSON AVIATION...DRAG/JOHNSON/ROBERTSON MARINE...DRAG/JOHNSON/ROBERTSON RIP CURRENTS...1207P CLIMATE...

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