Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 221953 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 353 PM EDT TUE JUL 22 2014 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO MOVE EASTWARD TONIGHT ALLOWING FOR A BETTER RETURN FLOW TOMORROW AHEAD OF A POTENT COLD FRONT. THE FRONT SHOULD MOVE THROUGH LATER ON WEDNESDAY INTO THURSDAY MORNING. HIGH PRESSURE WILL FILL IN BEHIND THE DEPARTING FRONT THROUGH THE FIRST HALF OF THE WEEKEND BEFORE A COMPLEX SYSTEM APPROACHES SUNDAY SPILLING INTO THE NEW WORK WEEK. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... CONDITIONS REMAINED FAIRLY STABLE OVER THE COASTAL PLAIN THIS AFTERNOON EVEN WITH THE DEVELOPMENT OF SOME CUMULUS. IT WAS MARGINALLY UNSTABLE OVER EASTERN PENNSYLVANIA AND NORTHERN NEW JERSEY. THERE WERE ISOLATED LIGHT RAIN SHOWERS IN LANCASTER COUNTY AND VICINITY AT MID AFTERNOON. WE WILL MENTION THE POSSIBILITY OF ISOLATED SHOWERS FROM BERKS COUNTY AND CHESTER COUNTY UP INTO NORTHERN NEW JERSEY UNTIL ABOUT 6 OR 7 O`CLOCK. THE CUMULUS WILL LIKELY BE ON THE DECREASE THIS EVENING WITH THE LOSS OF DAYTIME HEATING. HOWEVER, THE SOUTHERLY SURFACE FLOW WILL CONTINUE TO DRAW LOW LEVEL MOISTURE INTO OUR REGION. AS A RESULT, THERE MAY BE PATCHY LOW CLOUDS, FOG AND HAZE TOWARD MORNING. MINIMUM TEMPERATURES SHOULD RANGE FROM THE MIDDLE 60S TO THE LOWER 70S. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... THE GUIDANCE HAS BEEN FAIRLY CONSISTENT DURING THE PAST SEVERAL DAYS REGARDING THE FORECAST FOR WEDNESDAY. TEMPERATURES AT THE 850 HPA LEVEL ARE FORECAST TO RISE AROUND 18C OR 19C, SO MAXIMUM TEMPERATURES MAINLY IN THE LOWER 90S CONTINUE TO SEEM REASONABLE. DEW POINT READINGS SHOULD BE RIGHT AROUND 70 RESULTING IN MAXIMUM HEAT INDEX VALUES IN THE MIDDLE AND UPPER 90S. THE WIND IS ANTICIPATED TO FAVOR THE SOUTH ON THE COASTAL PLAIN AND THE SOUTHWEST INLAND AT SPEEDS AROUND 10 MPH. INSTABILITY WILL BE ON THE INCREASE THROUGH THE MORNING AND EARLY AFTERNOON WITH MIXED LAYER CAPE VALUES EXPECTED TO RISE AROUND 2500 J/KG IN AREAS ALONG AND TO THE NORTHWEST OF THE INTERSTATE 95 CORRIDOR. A BIT OF A MID LEVEL CAP MAY PREVENT MUCH ACTIVITY FROM DEVELOPING DURING THE EARLY TO MID AFTERNOON. HOWEVER, A LINE OF THUNDERSTORMS SHOULD DEVELOP AHEAD OF A COLD FRONT APPROACHING FROM THE NORTHWEST. THE CONVECTION WILL LIKELY MOVE INTO OUR NORTHWESTERN COUNTIES BY LATE AFTERNOON AND IT SHOULD REACH THE INTERSTATE 95 CORRIDOR DURING THE EARLY EVENING. THE STORM PREDICTION CENTER CONTINUES TO SUGGEST THAT THE GREATEST THREAT OF SEVERE WEATHER AHEAD OF THE FRONT WILL BE UP IN NEW ENGLAND. HOWEVER, A FEW STRONG STORMS AND ISOLATED SEVERE WEATHER REMAIN POSSIBLE IN OUR AREA. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... COLD FRONT SHOULD BE AT OUR DOORSTEP AT THE START OF THE LONGTERM PERIOD THOUGH AS THE CASE DURING THE SUMMER, IT WILL NOT A QUICK PASSAGE. UPPER LEVEL SUPPORT WITH THE RIGHT ENTRANCE REGION OF THE JET OVERHEAD AND DEEPER TROUGHING NUDGING IN FROM THE WEST COMBINED WITH PWATS NEARING 2 INCHES, AGAIN, COULD PRODUCE HEAVY RAIN WITH ANY OF THE STORMS. SHEAR VALUES WILL BE RATHER ROBUST, AROUND 25 KNOTS...BETTER THE FURTHER NORTH YOU GO, SO ORGANIZED CONVECTION SEEMS PLAUSIBLE AND THE STORMS WILL BE MOVING. WITH THE DEEPENING TROUGH EXPECTED OVERHEAD ON THURSDAY, THE FRONT SHOULD BE SLOW TO CLEAR THE REGION SO WE KEEP CHANCE TO LIKELY POPS IN ACROSS THE SOUTHERN ZONES THROUGH MOST OF THE AFTERNOON...COULD BE LONG IN THE TOOTH. THE BASE OF THE TROUGH BEGINS TO FLATTEN OUT BY FRIDAY, THOUGH NOT ENTIRELY BECOMING ZONAL. THIS YIELDS SLIGHTLY BELOW NORMAL TEMPERATURES AND DECREASED CHANCES FOR CONVECTION GIVEN A DRIER AIRMASS IN PLACE. STILL A BIT UNCERTAIN ABOUT THE SATURDAY EVENING TIMEFRAME AS SOME OF THE OPERATIONAL GUIDANCE SWINGS A PIECE ENERGY THROUGH THE BASE OF THE TROUGH WHICH COULD TOUCH OFF A COUPLE STRAY/ISOLATED SHOWERS...BETTER EAST THAN WEST WITH BETTER MOISTURE POOLING AND SEABREEZE INTERACTION. RIDGING BUILDS INTO THE WEST SENDING STRONGER SHORTWAVES OF ENERGY INTO THE TROUGH OVERHEAD ALLOWING FOR ANOTHER BOUT OF DEEPER TROUGHING. EXPECT UNSETTLED WEATHER THROUGH THE REMAINDER OF THE LONGTERM AS A SERIES OF EMBEDDED WAVES PUSHES THROUGH ALOFT TOUCHING OFF SHOWERS AND THUNDERSTORMS. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. SCATTERED TO BROKEN CLOUDS WITH BASES GENERALLY IN THE 4000 TO 5000 FOOT RANGE ARE ANTICIPATED FOR THE BALANCE OF THE AFTERNOON. ISOLATED RAIN SHOWERS ARE POSSIBLE AROUND KRDG AND KABE. THE CLOUD COVER IS FORECAST TO DECREASE DURING THE EVENING HOURS WITH THE LOSS OF DAYTIME HEATING. VFR CONDITIONS ARE ANTICIPATED FOR EARLY TONIGHT. INCREASING LOW LEVEL MOISTURE IN THE SOUTHERLY FLOW MAY RESULT IN THE DEVELOPMENT OF SOME LOW CLOUDS, HAZE AND FOG FOR LATE TONIGHT INTO EARLY WEDNESDAY MORNING. VFR CONDITIONS ARE EXPECTED FROM MID MORNING ON WEDNESDAY INTO THE MID AFTERNOON HOURS. HOWEVER, THUNDERSTORMS OUT AHEAD OF A COLD FRONT APPROACHING FROM THE NORTHWEST SHOULD IMPACT OUR REGION DURING THE LATE AFTERNOON AND EVENING HOURS. A SOUTHERLY WIND AROUND 5 TO 10 KNOTS TODAY SHOULD DIMINISH TO 6 KNOTS OR LESS FOR TONIGHT. A SOUTHWEST TO SOUTH WIND AROUND 10 KNOTS IS ANTICIPATED FOR WEDNESDAY. OUTLOOK... WEDNESDAY NIGHT AND THURSDAY...MVFR AND IFR CONDITIONS AT TIMES IN SHOWERS AND THUNDERSTORMS. PATCHY FOG THU MORNING. THURSDAY NIGHT THROUGH SATURDAY...MAINLY VFR. SUNDAY...SUB-VFR POSSIBLE IN SCATTERED SHOWERS AND THUNDERSTORMS. && .MARINE... HIGH PRESSURE OFF THE COAST AND A COLD FRONT APPROACHING FROM THE NORTHWEST SHOULD MAINTAIN A SOUTHERLY FLOW OVER THE COASTAL WATERS OF NEW JERSEY AND DELAWARE FOR TONIGHT AND WEDNESDAY. WIND SPEEDS WILL FAVOR THE 5 TO 15 KNOT RANGE. WAVE HEIGHTS ON OUR OCEAN WATERS SHOULD BE 2 TO 4 FEET. WAVES ON DELAWARE BAY ARE EXPECTED TO BE 2 FEET OR LESS. THERE IS A CHANCE OF THUNDERSTORMS LATE ON WEDNESDAY. OUTLOOK... THURSDAY THROUGH SUNDAY...HIGH PRESSURE OVERHEAD WILL KEEP SEAS AND WINDS BELOW SCA CRITERIA. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...HEAVENER NEAR TERM...IOVINO SHORT TERM...IOVINO LONG TERM...HEAVENER AVIATION...IOVINO/HEAVENER MARINE...IOVINO/HEAVENER

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