Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 260124 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 924 PM EDT FRI JUL 25 2014 .SYNOPSIS...
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SURFACE HIGH PRESSURE WILL MOVE FARTHER OFFSHORE ON SATURDAY SETTING UP A RETURN FLOW. A WARM FRONT CROSSES THE REGION LATE ON SATURDAY WHILE THE PARENT LOW PRESSURE SYSTEM MOVES THROUGH THE GREAT LAKES. THE ATTENDANT COLD FRONT SWINGS THROUGH LATE ON SUNDAY INTO MONDAY FOLLOWED BY ANOTHER HIGH PRESSURE SYSTEM.
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&& .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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HIGH PRESSURE WILL CONTINUE TO DRIFT OUT TO SEA OVERNIGHT. A LIGHT SOUTH TO SOUTHWEST SURFACE FLOW IS ANTICIPATED. TEMPERATURES SHOULD DROP INTO THE MIDDLE AND UPPER 50S UP NORTH AND INTO THE LOWER AND MIDDLE 60S ELSEWHERE. HIGH CLOUDS FROM THE WEST AND NORTHWEST WILL DRIFT OVERHEAD DURING THE NIGHT. THEY SHOULD BE THIN AND WILL LIKELY HAVE LIMITED IMPACT ON THE TEMPERATURES.
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... CONFIDENCE IS NOT HIGH IN EITHER DIRECTION ABOUT CONVECTION AND THE END RESULT FOR NOW IS A RATHER GENERIC VANILLA SUMMER`S DAY FORECAST FOR SATURDAY. THE MODELS HAVE BEEN PRETTY CONSISTENT IN POOLING DEW POINTS AS SATURDAY PROGRESSES IN OUR CWA. PARTLY BECAUSE OF THE AFOREMENTIONED SHORT WAVES AND ALSO LOOKS TO BE SOME SFC WIND CONVERGENCE. THEY ACTUAL SPIKE UPWARD HAS BECOME MORE LOGICAL FROM YESTERDAY WHERE SOME OF THE MODEL FCST SFC DEW POINTS WERE REACHING THE MID 70S. STILL MOS GUIDANCE IS FORECASTING DEW POINTS 5 TO 10F LOWER THAN THEIR OWN MODEL GUIDANCE. THIS PLUS TEETERING CLOSE TO THE EDGE OF THE AVAILABLE CAPE FOR THUNDER AND WHETHER OR NOT THE CAP WOULD HOLD. GIVEN THE SHORT WAVES ALOFT, THINKING THE CAP WONT. THIS LEAVES THE DEW POINTS. IF THEY DONT GET INTO THE MID 60S ALONG THE COASTAL PLAIN, CHANCES ARE THERE WONT BE ENOUGH CAPE. NORTH AND WEST THERE IS ALWAYS THE OROGRAPHIC INFLUENCE THAT MAY COMPENSATE FOR LOWER DEW POINTS. MODIFIED SOUNDING CONVECTIVE TEMPS ARE PREDICTED TO BE REACHED, SO WE DID EXPAND THE MENTION OF DURING THE AFTERNOON THUNDER GEOGRAPHICALLY. CONVERSELY SINCE MOST MESOSCALE MODELS ARE CONVERGING SOUTH AND EAST TOWARD THE HIGHER DEW POINT POOLING, WE DID LOWER POPS IN THE NORTHWEST PART OF OUR CWA. PREDICTED 1395 1000-850MB THICKNESSES ARE NOT BUYING MAX TEMPS AS HIGH AS THEY HAVE DONE IN PAST SUMMERS. FULL SUN MACROS LOOK OVERCOOKED AND MAX TEMPS WERE KEPT CLOSER TO 10-11C OVER PREDICTED 925MB TEMPS. THIS IS CLOSE TO STAT GUIDANCE AND CONTINUITY. GFS THERMAL GUIDANCE WENT DOWN ABOUT 1-2C FROM THURSDAY`S LEVELS AOB 850MB. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... SUNDAY...A DECAYING MCS SHOULD BE DIVING WELL TO THE SOUTHWEST OF OUR REGION AS ONE MID-LEVEL SHORTWAVE CRUISES THROUGH. SURFACE WARM FRONT SHOULD BE LIFTING THROUGH DURING THE EARLY PART OF THE MORNING. MOISTURE WILL CONTINUE TO INCREASE WITH A SOUTHWEST SURFACE FLOW WITH PWATS EXCEEDING 1.5 INCHES. EARLY MORNING SHOWERS AND THUNDERSTORMS SHOULD BE WANING BY LATE MORNING AS MOST OF THE OPERATIONAL GUIDANCE SHOWS THE REGION BREAKING OUT. NOT QUITE SURE HOW LONG LIVED THE BREAK WILL BE AS CONVECTIVE TEMPERATURES SHOULD EASILY BE MET AS HIGHS APPROACH 90F SO WE CONTINUE WITH CHANCE POPS. BETTER FORCING MOVES IN ALOFT WITH A MUCH STRONGER SHORTWAVE AND APPROACHING COLD FRONT LATER ON SUNDAY. BETTER HEIGHT FALLS, SHEAR PROFILES AND LESS CAPPING SHOULD ALLOW FOR MUCH MORE ORGANIZED CONVECTION TO OCCUR. SPC HAS US IN DAY 3 OUTLOOK AT THIS TIME SO WILL CONTINUE WITH THE HWO HIGHLIGHTING. MONDAY...COLD FRONT WILL CONTINUE TO MOVE THROUGH THE REGION, THOUGH NOT AT A BLISTERING PACE. WEAK SURFACE CYCLOGENESIS IS POSSIBLE ON MONDAY AS THE FRONT SITS JUST TO OUR EAST SO WE KEEP CHANCE POPS IN PLACE DURING THE DAY. TEMPERATURES SHOULD END UP BEING AROUND AVERAGE ACROSS THE EAST AND SLIGHTLY BELOW ACROSS THE WEST. TUESDAY - THURSDAY...DRYING TREND SHOULD COMMENCES ACROSS A MAJORITY OF THE REGION, BUT WITH THE MID-LEVEL TROUGH/COLD POOL ALOFT, AND THE SLIGHTEST HINT OF INSTABILITY AROUND, ISOLATED SHOWERS ARE POSSIBLE ON TUESDAY...BETTER FURTHER NORTH. THE CHANCES FOR SHOWERS DECREASES EACH AFTERNOON THEREAFTER. TEMPERATURES SHOULD END UP BEING BELOW NORMAL FOR LATE JULY STANDARDS. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD WITH AN INCREASE IN CIRRUS DURING THE NIGHT AND THE DEVELOPMENT OF CUMULUS ON SATURDAY WITH BASES ABOVE 4500 FEET. THERE IS THE POTENTIAL FOR ISOLATED SHOWERS AND THUNDERSTORMS ON SATURDAY. HOWEVER, THEIR COVERAGE SHOULD BE LIMITED AND THEY MAY VERY WELL NOT IMPACT ANY OF OUR TAF SITES. A LIGHT WIND FAVORING THE SOUTHWEST AND SOUTH OVERNIGHT AND ON SATURDAY MORNING IS FORECAST TO INCREASE TO AROUND 8 OR 10 KNOTS FOR SATURDAY AFTERNOON. OUTLOOK... SUNDAY - MONDAY...SUB-VFR CONDITIONS EXPECTED IN AREAS OF SHOWERS AND THUNDERSTORMS. TUESDAY - WEDNESDAY...VFR.
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&& .MARINE...
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A SOUTH TO SOUTHWEST WIND AT 10 TO 15 KNOTS EARLY THIS EVENING SHOULD DIMINISH TO 5 TO 10 KNOTS OVERNIGHT. THE HIGH PRESSURE SYSTEM WILL BE MOVING OFFSHORE AND A SLIGHTLY STRONGER SYNOPTIC SCALE RETURN FLOW IS PREDICTED FOR SATURDAY. AS IS TYPICALLY THE CASE, MODEL GUIDANCE OVER THE WATERS IS NORMALLY OVERDONE IN CASES LIKE THIS AND WINDS AND SEAS WERE KEPT BELOW SCA CRITERIA THRU THE DAY ON SATURDAY. OUTLOOK... SUNDAY...SUB-SCA EXPECTED WITH SCATTERED SHOWERS AND THUNDERSTORMS. MONDAY...SEAS MAY BUILD TO SCA LEVELS UNDER A STRENGTHENING SOUTHWEST SURFACE FLOW. TUESDAY - WEDNESDAY...SUB-SCA CONDITIONS EXPECTED.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...HEAVENER NEAR TERM...IOVINO SHORT TERM...GIGI LONG TERM...HEAVENER AVIATION...IOVINO/HEAVENER MARINE...GIGI/HEAVENER

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