Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 211946 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 346 PM EDT MON JUL 21 2014 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO INFLUENCE OUR WEATHER FROM TONIGHT INTO EARLY WEDNESDAY. A COLD FRONT IS FORECAST TO APPROACH FROM THE NORTHWEST ON WEDNESDAY AND IT SHOULD PASS THROUGH OUR REGION FROM LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. HIGH PRESSURE IS EXPECTED TO FOLLOW FOR FRIDAY AND SATURDAY. A WARM FRONT FROM THE SOUTH AND LOW PRESSURE FROM THE WEST ARE ANTICIPATED TO AFFECT OUR REGION ON SUNDAY AND MONDAY. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... REGIONAL RADAR SHOWS A FEW WEAK RETURNS ACROSS CENTRAL PENNSYLVANIA THAT ARE SLOWLY DRIFTING TOWARDS THE EAST-NORTHEAST. LATEST SREF PROBS SHOW MAINLY THE POCONOS AND OUR WESTERN ZONES SEEING SOME SHOWERY ACTIVITY THOUGH NOT MUCH IF ANY ACCUMULATION IS EXPECTED. LATEST SPC MESOANALYSIS SHOWS LITTLE IN THE WAY OF SURFACE BASED OR MUCAPE. THERE IS STILL A DECENT CAP IN PLACE AROUND 650MB, BELOW THE FREEZING LEVEL, WITH AMPLE DRY AIR SO DID NOT ADD THUNDER TO THE SHOWERS THIS EVENING. THE ACTIVITY SHOULD BEGIN TO WANE WITH THE LOSS OF HEATING AND UPPER LEVEL SUPPORT MOVING FURTHER TOWARDS THE NORTHEAST. ELSEWHERE WE SHOULD REMAIN DRY WITH THE STRATOCU DECK DIMINISHING AFTER SUNSET. SURFACE RIDGING CONTINUES TO SLIDE TOWARDS THE NORTHEAST TONIGHT WITH AN INCREASE IN LOW-LEVEL MOISTURE EXPECTED. DEWPOINTS SHOULD BE ABLE TO CLIMB INTO THE MID 60S OVERNIGHT WITH RELATIVELY LIGHT WINDS IN PLACE...AT LEAST AFTER MIDNIGHT. DO NOT THINK TEMPERATURES WILL BE ABLE TO CROSSOVER TONIGHT, LIKE THEY DID IN PLACES THIS MORNING, BUT IT LOOKS LIKE A DECENT SETUP FOR MORE FOG AND POSSIBLE STRATUS FORMATION LATE TONIGHT...ADDED MORE PATCHY FOG. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... ANY FOG AND STRATUS WILL BURN/LIFT BY LATE MORNING GIVING WAY TO A SELF DESTRUCTING SKY AS TEMPERATURES CLIMB A COUPLE DEGREES WARMER THAN TODAY. CONVECTIVE TEMPERATURES ARE ABOUT THE SAME AS TODAY SO EXPECTING MORE SCATTERED TO BROKEN STRATOCU FORMING TOMORROW AFTERNOON. HI-RES GUIDANCE IS AGAIN PEGGING THE HIGHER RIDGES AND TERRAIN WITH QPF BULLSEYES WHICH MAKE SENSE GIVEN THE INCREASE OF MOISTURE AND STRONGER INSTABILITY EXPECTED TOMORROW. LOOKING AT AN AIR MASS THUNDERSTORM TYPE OF DAY EVEN WITH MID-LEVEL CAPPING STILL PRESENT AS SURFACE BASED CAPE VALUES SURGE INTO CLOSE TO 1500J/KG WHICH SHOULD BE ENOUGH TO PUNCH THROUGH THE CAP. TEMPERATURES, AS STATED ABOVE, WILL BE A COUPLE DEGREES WARMER WITH BUILDING HEIGHTS IN THE LOW-LEVELS AND A SURFACE RETURN FLOW ESTABLISHING ITSELF. A STRAIGHT MET/MAVMOS BLEND WAS USED. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... SURFACE HIGH PRESSURE IS EXPECTED TO CONTINUE MOVING OFF THE COAST ON TUESDAY NIGHT. THE RESULTING SOUTHERLY FLOW WILL BRING ADDITIONAL LOW LEVEL MOISTURE INTO OUR REGION. TUESDAY NIGHT IS FORECAST TO BE RATHER MUGGY WITH MINIMUM TEMPERATURES MAINLY IN THE UPPER 60S AND LOWER 70S. PATCHY FOG IS POSSIBLE. TEMPERATURES AT THE 850 HPA LEVEL ARE ANTICIPATED TO RISE AROUND 18C ON WEDNESDAY. WE CONTINUE TO EXPECT MAXIMUM TEMPERATURES MOSTLY IN THE LOWER 90S WITH A FAIR AMOUNT OF SUNSHINE, ESPECIALLY THROUGH MID AFTERNOON. HEAT INDEX VALUES SHOULD PEAK IN THE MIDDLE AND UPPER 90S. CONDITIONS WILL REMAIN COOLER THAN THAT IN THE ELEVATED TERRAIN UP NORTH AND IN AREAS ALONG THE COAST. THE POTENTIAL FOR SCATTERED THUNDERSTORMS WILL OVERSPREAD OUR REGION FROM THE NORTHWEST DURING THE AFTERNOON IN ADVANCE OF AN APPROACHING COLD FRONT. WHILE A BIT OF A CAP IN THE MID LEVELS MAY INITIALLY PREVENT THUNDERSTORM DEVELOPMENT, THE CAP IS EXPECTED TO ERODE. MIXED LAYER CAPE VALUES ARE FORECAST TO RISE AROUND 2000 J/KG FROM AROUND THE INTERSTATE 95 CORRIDOR NORTHWESTWARD DURING WEDNESDAY AFTERNOON. THE MODELS HAVE BEEN TRENDING TOWARD A FASTER COLD FRONTAL PASSAGE IN OUR REGION. THE BOUNDARY SHOULD WORK ITS WAY THROUGH MOST OF OUR FORECAST AREA DURING THE LATE WEDNESDAY NIGHT AND THURSDAY MORNING TIME FRAME. WE WILL CONTINUE TO MENTION A CHANCE OF SHOWERS AND THUNDERSTORMS FOR THAT PERIOD OF TIME. TEMPERATURES SHOULD REMAIN WARM FOR WEDNESDAY NIGHT. WE HAVE LOWERED THE MAXIMUM TEMPERATURES FOR THURSDAY INTO THE LOWER AND MIDDLE 80S DUE TO THE MORE PROGRESSIVE TIMING ON THE FRONT. SHOWERS MAY LINGER IN THE SOUTHERN PART OF OUR FORECAST AREA INTO THURSDAY NIGHT. OTHERWISE, HIGH PRESSURE FROM THE NORTHWEST AND WEST IS ANTICIPATED TO BUILD ACROSS OUR REGION FOR FRIDAY AND SATURDAY. HIGHS SHOULD BE MAINLY IN THE 80S WITH LOWS GENERALLY IN THE 60S. A MID LEVEL TROUGH SHOULD BEGIN TO RE-ESTABLISH ITSELF OVER THE GREAT LAKES AND THE NORTHEASTERN STATES DURING THE SUNDAY AND MONDAY TIME FRAME. THE GUIDANCE DIFFERS IN THE HANDLING OF THE ASSOCIATED SURFACE FEATURES. NEVERTHELESS, IT APPEARS AS THOUGH THERE WILL BE A CHANCE OF SHOWERS AND THUNDERSTORMS ON BOTH DAYS ALONG WITH NEAR NORMAL TEMPERATURES. && .AVIATION /20Z MONDAY THROUGH SATURDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THIS AFTERNOON - LATE EVENING...VFR. WINDS GENERALLY LESS THAN 8 KNOTS OUT OF THE SOUTH-SOUTHEAST. SEABREEZE FRONT HAS ALREADY PUSHED THROUGH ACY AND MIV BUT SHOULD NOT MAKE IT TO I-95. STRATOCU BASES AROUND 5-7KFT. OVERNIGHT...MOSTLY VFR. HIGH PRESSURE OFFSHORE WILL ALLOW FOR MORE MOISTURE TO MOVE INTO THE REGION. POCKETS OF FOG AND STRATUS ARE POSSIBLE AT OUR WESTERN AND EASTERN TERMINALS, THOUGH NOT CONFIDENT ON THE STRATUS PORTION. WINDS WILL BE LIGHT AND VARIABLE. TOMORROW...VFR. FOG AND STRATUS BURN/LIFT TO VFR. WINDS BACK MORE TOWARDS THE SOUTH-SOUTHWEST, NOT EXPECTING A SEABREEZE INFLUENCE. OUTLOOK... TUESDAY NIGHT AND WEDNESDAY...MAINLY VFR. POSSIBLE LATE NIGHT AND EARLY MORNING MVFR OR IFR CONDITIONS IN LOW CLOUDS, FOG AND HAZE. A CHANCE OF AFTERNOON THUNDERSTORMS. WEDNESDAY NIGHT AND THURSDAY...MVFR AND IFR CONDITIONS AT TIMES IN SHOWERS AND THUNDERSTORMS. THURSDAY NIGHT THROUGH SATURDAY...MAINLY VFR. && .MARINE... SUB-SCA CONDITIONS ARE EXPECTED ACROSS THE WATERS TONIGHT AND TOMORROW WITH HIGH PRESSURE STILL HAVING A INFLUENCE ON THE REGION. EAST-SOUTHEAST WINDS WILL GRADUALLY VEER TOWARDS THE SOUTH-SOUTHWEST BY TOMORROW AFTERNOON AS SEAS REMAIN NEARLY IN STEADY STATE AROUND 3 FEET. OUTLOOK... TUESDAY NIGHT THROUGH SATURDAY...NO MARINE HEADLINES ARE ANTICIPATED. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...IOVINO NEAR TERM...HEAVENER SHORT TERM...HEAVENER LONG TERM...IOVINO AVIATION...IOVINO/HEAVENER MARINE...IOVINO/HEAVENER

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