Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 300045 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 845 PM EDT WED JUL 29 2015 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO MOVE OFFSHORE TONIGHT. A WEAKENING COLD FRONT WILL SLOWLY MOVE THROUGH OUR REGION ON THURSDAY NIGHT. THE NEXT WEAK COLD FRONT SHOULD CROSS OUR AREA LATE SATURDAY INTO SUNDAY, FOLLOWED BY HIGH PRESSURE EARLY NEXT WEEK. A POTENTIALLY STRONGER COLD FRONT IS EXPECTED TO ARRIVE ON WEDNESDAY. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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A MID LEVEL RIDGE AXIS WILL CONTINUE TO DRIFT EASTWARD OVERNIGHT. LATEST RADAR IMAGERY SHOWED PRECIP HAS ENDED ACRS THE DELMARVA. MOST OF THE MODEL GUIDANCE IS SUGGESTING THAT SOME REMNANT CONVECTION FROM VIRGINIA AND VICINITY WILL DRIFT NORTHEASTWARD AND OVER OUR FORECAST AREA LATE TONIGHT. AS A RESULT, WE HAVE INDICATED AN INCREASE IN CLOUD COVER ALONG WITH A CHANCE OF SHOWERS AT THAT TIME. CONDITIONS WILL REMAIN VERY WARM AND HUMID OVERNIGHT. MINIMUM TEMPERATURES SHOULD BE MOSTLY IN THE 70S WITH A LIGHT SOUTHWEST WIND. MADE SOME MINOR CHANGES TO CURRENT FCST.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... THURSDAY IS FORECAST TO BEGIN WITH A MOSTLY CLOUDY SKY ALONG WITH SOME LINGERING RAIN SHOWERS. THE CLOUDS ARE EXPECTED TO DECREASE FOR THE LATE MORNING AND EARLY AFTERNOON HOURS BEFORE THE CONVECTION ASSOCIATED WITH THE FRONTAL BOUNDARY APPROACHING FROM THE NORTHWEST ARRIVES IN OUR REGION. WE ARE ANTICIPATING THAT SHOWERS AND THUNDERSTORMS WILL BEGIN TO SPREAD INTO OUR NORTHWESTERN COUNTIES AROUND 200 TO 300 PM ON THURSDAY. THE PRECIPITATION WILL WORK ITS WAY SOUTHEASTWARD, REACHING THE INTERSTATE 95 CORRIDOR ABOUT 400 PM TO 500 PM AND THE COAST TOWARD 700 PM. PRECIPITABLE WATER VALUES ARE FORECAST TO INCREASE IN EXCESS OF 2 INCHES SO WE WILL CONTINUE TO MENTION THE POTENTIAL FOR HEAVY RAINFALL. ALSO, SOME OF THE MORE WELL DEVELOPED THUNDERSTORMS MAY BRING STRONG WIND GUSTS. WE ARE EXPECTING HIGH TEMPERATURES NEAR 90 DEGREES IN MUCH OF OUR FORECAST AREA. THE AIR WILL REMAIN VERY HUMID AND HEAT INDEX VALUES SHOULD REACH THE MIDDLE AND UPPER 90S BEFORE THE AFTERNOON SHOWERS AND THUNDERSTORMS ARRIVE. AS A RESULT, WE WILL KEEP THE EXCESSIVE HEAT WARNING IN EFFECT UNTIL 600 PM THURSDAY FOR OUR HIGHLY URBANIZED AREAS ALONG THE INTERSTATE 95 CORRIDOR. A SOUTHWEST WIND AROUND 10 MPH IS ANTICIPATED FOR THURSDAY. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... OVERVIEW... A CLOSED MID-LEVEL LOW OVER HUDSON`S BAY WILL MAINTAIN A TROUGH IN THE EAST CONUS AND A GENERAL CYCLONIC FLOW ALOFT THROUGH THE PERIOD. THERE IS SOME MODEL DISAGREEMENT REGARDING S/WV ENERGY ENTERING THE GREAT LAKES REGION ON SUNDAY...AND TO WHAT EXTENT THE TROUGH AMPLIFIES AS A RESULT. THE ECMWF IS MORE AMPLIFIED THAN THE GFS...WHICH RESULTS IN MORE TROPICAL MOISTURE MOVING INTO THE REGION...ASSOCIATED WITH LOW- PRESSURE DEVELOPMENT IN THE GMEX. A LOT OF UNCERTAINTY HERE AT THE D+5 TIME FRAME. THE BEST CHANCES FOR PRECIP WILL BE WITH A COLD FROPA ON SAT...AND ANOTHER LATE TUE/EARLY WED. ABOVE NORMAL TEMPERATURES EXPECTED THRU THE PERIOD. DETAILS... THU NIGHT...COLD FRONT WILL SLOWLY MOVE OFFSHORE...AS A WAVE OF LOW PRESSURE DEVELOPS ALONG IT INVOF THE OUTER BANKS. THIS WILL RESULT IN CHCS FOR SHRA/TSRA THRU MUCH OF THE NIGHT OVER DELMARVA. WITH PRECIPITABLE WATER VALUES OF 1.5 TO 2 INCHES AND SLOW STORM MOTION...THE MAIN CONCERN WILL BE HEAVY DOWN- POURS. CONDITIONS WILL ALSO BE FAVORABLE FOR THE DEVELOPMENT OF SOME PATCHY GROUND FOG IN THE NORMALLY PRONE LOCATIONS. FRI...S/WV RIDGING ALOFT ALONG WITH A VERY DRY AIR MASS WILL RESULT IN A MOSTLY SUNNY DAY. CONVECTIVE TEMPS MAY BE OUT OF REACH...SO EVEN CU MAY BE FEW AND FAR BETWEEN. THE GRADIENT MAY WEAKEN ENOUGH FOR A SEA-BREEZE DEVELOPMENT LATE IN THE AFTN. MAX TEMPS WILL BE IN THE 80S W/ L90S IN DELMARVA ALONG WITH A NOTICEABLY LESS HUMID AIR MASS. SAT THRU SUN...THUNDERSTORMS ARE POSSIBLE OVER THE LEHIGH VALLEY AND POCONOS LATE SAT AFTN/EARLY EVE...THEN SOUTHEAST TOWARD THE COASTLINE SAT NIGHT. S/WV TROUGH ALOFT WILL LEAD TO STEEP MID-LEVEL LAPSE RATES...WHILE A COLD FRONT MOVING INTO THE REGION POOLS LOW LEVEL MOISTURE...AND PROVIDES A SOURCE OF LIFT. ML CAPE IS MODELED AROUND 1.5 KJ...WHILE BULK SHEAR APPROACHES 40 KNOTS. BOTH OF THESE FACTORS ARE MOST FAVORABLE OVER THE LEHIGH VALLEY AND POCONOS. ATTM... MAIN THREAT APPEARS TO BE GUSTY WINDS...WITH INVERTED-V MODEL SOUNDINGS...AS WELL AS D-CAPE APPROACHING 1.4 KJ. HAIL IS ALSO A THREAT...AS WBZ VALUES FALL BLW 10 KFT IN THE AFTN.... AS WELL AS H50 TEMPS AROUND -12C. OTHERWISE...A PARTLY TO MOSTLY SUNNY SATURDAY IS ANTICIPATED. SUN...S/WV RIDGING ALOFT AS HIGH PRES BRIEFLY BUILDS IN BEHIND DEPARTING COLD FRONT. THIS WILL PROMOTE A MOSTLY SUNNY AND DRY DAY. MON THRU WED...THERE IS A LOT OF UNCERTAINTY DURING THIS TIME FRAME. THE OUTCOME HINGES ON JUST HOW MUCH THE EAST COAST TROUGH AMPLIFIES...WHICH WILL DETERMINE WHETHER OR NOT GULF MOISTURE MAKES IT THIS FAR NORTH ON MON/TUE. SOME DIURNALLY DRIVEN SHRA/TSRA ARE POSSIBLE MON...W/ A BETTER CHANCE WITH THE APPROACH OF A COLD FRONT TUE. THE FRONT MAY SLOW DOWN AS IT MOVES THRU THE REGION... SO WED MAY BE UNSETTLED. && .AVIATION /01Z THURSDAY THROUGH MONDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. MID LEVEL CLOUDS AND SCATTERED SHOWERS ARE FORECAST TO OVERSPREAD OUR REGION LATE TONIGHT. SOME MVFR CEILINGS MAY DEVELOP AROUND KRDG AND KABE. THE CLOUDS AND SHOWERS ARE EXPECTED TO LIFT TO OUR NORTH AND NORTHEAST DURING THE LATE MORNING AND EARLY AFTERNOON. CONFIDENCE REMAINS LOW ON THE OVERNIGHT PRECIP CHCS. SHOWERS AND THUNDERSTORMS ARE ANTICIPATED TO APPROACH FROM THE NORTHWEST EARLY IN THE AFTERNOON. THE LINE OF SHOWERS AND THUNDERSTORMS IS FORECAST TO MOVE ACROSS OUR EIGHT TAF SITES FROM NORTHWEST TO SOUTHEAST BETWEEN ABOUT 1900Z AND 2300Z. THERE ARE STILL SOME QUESTIONS REGARDING TIMING. LATER SHIFTS CAN REFINE. A SOUTHWEST WIND AT 5 TO 10 KNOTS INTO THIS EVENING SHOULD DECREASE TO 6 KNOTS OR LESS FOR TONIGHT. A SOUTHWEST WIND AROUND 8 TO 10 KNOTS IS EXPECTED FOR THURSDAY. OUTLOOK... THU NIGHT AND FRI...VFR CONDITIONS EXPECTED...EXCEPT FOR PATCHY GROUND FOG IN THE 06Z-12Z FRIDAY TIME FRAME. SAT AND SAT NIGHT...MAINLY VFR...WITH MVFR POSSIBLE SAT EVE AND EARLY SAT NIGHT IN SHRA/TSRA. SUN AND MON...VFR CONDITIONS EXPECTED.
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&& .MARINE... WEAK HIGH PRESSURE WILL INFLUENCE THE COASTAL WATERS OF NEW JERSEY AND DELAWARE FOR TONIGHT. A FRONTAL BOUNDARY IS FORECAST TO APPROACH FROM THE NORTHWEST ON THURSDAY. A SOUTH SOUTHWEST WIND IS EXPECTED TO INCREASE TO 10 TO 15 KNOTS WITH GUSTS AROUND 20 KNOTS ON THURSDAY AFTERNOON. WAVE HEIGHTS ON OUR OCEAN WATERS MAY BUILD TO AROUND 4 FEET. CONDITIONS SHOULD REMAIN JUST BELOW THE SMALL CRAFT ADVISORY CRITERIA. SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THE FRONTAL BOUNDARY ARE EXPECTED TO ARRIVE LATE ON THURSDAY. OUTLOOK... FRI THRU MON...SUB-SCA WINDS AND SEAS EXPECTED DURING THIS TIME. && .RIP CURRENTS...
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A MODERATE RISK OF RIP CURRENTS IS BEING FORECAST FOR THURSDAY, WITH INCREASING S TO SWLY FLOW AHEAD OF THE CDFNT AND THE FULL MOON ON FRIDAY.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...EXCESSIVE HEAT WARNING UNTIL 6 PM EDT THURSDAY FOR PAZ070-071- 102-104-106. NJ...EXCESSIVE HEAT WARNING UNTIL 6 PM EDT THURSDAY FOR NJZ015- 017>019. DE...EXCESSIVE HEAT WARNING UNTIL 6 PM EDT THURSDAY FOR DEZ001. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...FRANCK/GORSE NEAR TERM...IOVINO/NIERENBERG SHORT TERM...IOVINO LONG TERM...FRANCK AVIATION...FRANCK/IOVINO MARINE...FRANCK/GORSE/IOVINO

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