Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 260957 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 557 AM EDT TUE APR 26 2016 .SYNOPSIS... A FRONTAL BOUNDARY LOCATED TO OUR NORTH WILL SLOWLY PUSH SOUTHWARD ACROSS THE AREA TODAY AS AN AREA OF LOW PRESSURE MOVES ALONG THE BOUNDARY. THE FRONT WILL PUSH SOUTH OF THE AREA OVERNIGHT INTO WEDNESDAY MORNING AND STALL TO OUR SOUTH. ANOTHER AREA OF LOW PRESSURE WILL MOVE ALONG THIS BOUNDARY TO OUR SOUTH LATE THURSDAY INTO THURSDAY NIGHT. OUR AREA WILL REMAIN ON THE SOUTHERN EDGE OF HIGH PRESSURE CENTERED ACROSS CENTRAL CANADA OVER THE WEEKEND. AN AREA OF LOW PRESSURE AND ASSOCIATED FRONTAL BOUNDARIES MAY AFFECT THE AREA EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... IT WAS AN ACTIVE OVERNIGHT PERIOD IN MUCH OF OUR REGION WITH SCATTERED SHOWERS AND THUNDERSTORMS. SOME OF THE THUNDERSTORMS THAT PASSED ACROSS NORTHERN DELAWARE AND SOUTHERN NEW JERSEY PRODUCED HAIL WHILE SOME OF THE THUNDERSTORMS IN OUR NORTHERN COUNTIES WERE ACCOMPANIED BY WIND GUSTS AROUND 35 MPH. THE INITIAL BATCHES OF CONVECTION THAT DEVELOPED IN THE WARM ADVECTION WERE BEGINNING TO MOVE AWAY TO OUR EAST AROUND 400 AM AND THERE SHOULD BE A BIT OF A BREAK THIS MORNING WITH JUST SOME SHOWERS AND ISOLATED THUNDER PASSING ACROSS OUR NORTHERN COUNTIES. WE ARE EXPECTING SOME SUNSHINE ACROSS THE SOUTHERN HALF OF OUR FORECAST AREA FOR THIS MORNING INTO THE AFTERNOON, WITH A MOSTLY CLOUDY SKY OVER THE NORTH. TEMPERATURES ARE EXPECTED TO RISE INTO THE LOWER 80S IN THE SOUTH AND MAINLY INTO THE 70S IN THE NORTH. THE ELEVATED TERRAIN SHOULD STAY IN THE 60S. DAYTIME HEATING WILL RESULT IN INCREASING INSTABILITY WITH CAPE VALUES ANTICIPATED TO RISE AROUND 1000 J/KG IN ADVANCE OF A COLD FRONT THAT IS EXPECTED TO DROP THROUGH OUR REGION LATE IN THE DAY. THE STORM PREDICTION CENTER HAS OUR REGION EITHER UNDER ITS MARGINAL OR SLIGHT RISK DESIGNATION FOR SEVERE WEATHER. AS A RESULT, WE HAVE INCLUDED ENHANCED WORDING WITH THE THUNDERSTORMS FOR THIS AFTERNOON TO INDICATE A POTENTIAL FOR GUSTY WINDS AND HAIL. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/... THE COLD FRONT IS EXPECTED TO EXTEND THROUGH THE PHILADELPHIA METROPOLITAN AREA AROUND 800 PM AND IT SHOULD REACH SOUTHERN DELAWARE AND ITS ADJACENT COASTAL WATERS BY MIDNIGHT. THE ARRIVAL OF THE FRONT SHOULD BRING AN END TO THE PRECIPITATION. HOWEVER, CLOUDS ARE ANTICIPATED TO LINGER THROUGH MUCH OF THE NIGHT. THE WIND SHOULD SETTLE INTO THE NORTH AND NORTHEAST BEHIND THE COLD FRONT. TEMPERATURES ARE FORECAST TO DROP INTO THE 40S AND 50S. && .LONG TERM /WEDNESDAY THROUGH MONDAY/...
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THE COLD FRONT WILL BECOME STATIONARY NEAR THE NC-VA BORDER WEDNESDAY. DRIER AND COOLER AIR WILL WORKS ITS WAY INTO THE REGION AS CANADIAN HIGH PRESSURE CENTERED NEAR THE NORTHWEST PASSAGES RIDGES DOWN TOWARD US. HOWEVER, THE DRIER AIR MAY STRUGGLE TO MAKE IT INTO OUR FAR SOUTHERN ZONES, RESULTING IN CLOUDY SKIES THAT PERSIST INTO MOST OF WEDNESDAY ACROSS THE DELMARVA. LEE CYCLOGENESIS IS CURRENTLY TAKING PLACE IN THE CO FRONT RANGE OF THE ROCKIES. THIS SURFACE LOW WILL MEANDER OVER THE CENTRAL PLAINS FOR THE NEXT FEW DAYS AS THE UPPER TROUGH TIED TO THE SURFACE LOW REMAINS CUTS OFF. THE CUTOFF LOW IS FORECAST TO EVENTUALLY WEAKEN AND BECOME AN OPEN WAVE BY THURSDAY. IN RESPONSE TO THE EVOLVING UPPER PATTERN, THE SURFACE LOW WILL PROGRESS EASTWARD ALONG THE STATIONARY BOUNDARY TO OUR SOUTH ON THURSDAY. A SECONDARY WAVE OF LOW PRESSURE MAY DEVELOP AND RIDE THE FRONT ON FRIDAY. OVERRUNNING PRECIP SHOULD EXPAND NORTHWARD LATE WEDNESDAY NIGHT INTO THURSDAY AS THE FLOW BACKS MORE OUT OF THE SOUTH AHEAD OF THE LOW AND ISENTROPIC LIFT STRENGTHENS ALONG AND ON THE COOL SIDE OF THE BOUNDARY. THERE IS STILL UNCERTAINTY REGARDING HOW FAR NORTH THE FRONT AND PRECIP ADVANCES WITH DRIER AIR BEING REINFORCED BY HIGH PRESSURE ANCHORED TO OUR NORTH. THERE IS SOME EVIDENCE FROM GUIDANCE THAT EVAPORATIVE COOLING AT THE ONSET COULD LEAD TO A COLD AIR DAMMING PATTERN IF THERE IS ENOUGH LOW-LEVEL DRY AIR IN PLACE WHEN THE OVERRUNNING PRECIP MOVES IN. THIS WOULD KEEP THE FORECAST AREA ON THE COLD SIDE OF THE BOUNDARY. WE WILL CONTINUE TO SHOW THE HIGHEST POPS ACROSS OUR SOUTHERN AREAS DUE TO THE PROXIMITY OF THE FRONT. THERE COULD CONTINUE TO BE SOME SHOWERS DURING THE DAY FRIDAY AS A SHORT WAVE PUSHES ACROSS THE AREA AND THE FRONT CONTINUES TO PUSH FURTHER TO OUR SOUTH. SATURDAY LOOKS DRY AS HIGH PRESSURE BRIEFLY BUILDS BACK INTO THE MID ATLANTIC. SHOWERS MAY RETURN SUNDAY INTO MONDAY AS YET ANOTHER WAVE OF LOW PRESSURE IS EXPECTED TO ORGANIZE OVER THE GREAT PLAINS AND TRACK EASTWARD ALONG THE STATIONARY FRONT.
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&& .AVIATION /10Z TUESDAY THROUGH SATURDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THE SHOWERS AND THUNDERSTORMS THAT AFFECTED SOME OF OUR TAF SITES DURING THE NIGHT WILL CONTINUE TO MOVE AWAY TO OUR EAST EARLY THIS MORNING. MAINLY VFR CONDITIONS ARE ANTICIPATED FOR THIS MORNING WITH SCATTERED TO BROKEN MID LEVEL CLOUDS WITH BASES ABOVE 7000 FEET. THE WIND SHOULD BE RATHER LIGHT EARLY THIS MORNING BUT IS WILL BECOME WEST SOUTHWEST FOR THE MID TO LATE MORNING HOURS WITH SPEEDS INCREASING TO 12 TO 16 KNOTS AND GUSTS NEAR 25 KNOTS. THE AFTERNOON IS EXPECTED TO BEGIN WITH VFR CONDITIONS ALONG WITH A CONTINUATION OF THE GUSTY WEST SOUTHWEST WIND. HOWEVER, A COLD FRONT APPROACHING FROM THE NORTH SHOULD BRING SHOWERS AND THUNDERSTORMS. THE THUNDERSTORMS WILL BE ACCOMPANIED BY BRIEFLY MODERATE TO HEAVY RAINFALL, LOW CEILING AND VISIBILITY VALUES, AND PERHAPS WIND GUSTS IN EXCESS OF 35 KNOTS. THE FRONT IS ANTICIPATED TO PASS THROUGH KABE, KRDG AND KTTN BETWEEN ABOUT 2200 AND 2300Z BRINGING AND END TO THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS. THE FRONT IS EXPECTED TO ARRIVE AT KPNE AND KPHL AROUND 0000Z, AND AT KILG, KACY AND KMIV ABOUT 0100Z. THE WIND IS FORECAST TO SHIFT TO THE NORTHWEST, THEN TO THE NORTH AND NORTHEAST AND SPEEDS SHOULD DECREASE TO AROUND 8 TO 12 KNOTS. OUTLOOK... WEDNESDAY...MVFR CIGS POSSIBLE FOR THE SOUTHERN TWO-THIRDS OF THE AREA, WITH VFR POSSIBLE NORTHERN AREAS. WEDNESDAY NIGHT...VFR EXPECTED. THURSDAY-THURSDAY NIGHT...VFR EARLY, BECOMING MVFR OR IFR LATE IN THE DAY AND OVERNIGHT WITH RAIN POSSIBLE. FRIDAY-FRIDAY NIGHT...MVFR CIGS POSSIBLE WITH SCATTERED SHOWERS. SATURDAY...VFR CIGS, WITH PERIODS OF MVFR POSSIBLE. && .MARINE...
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THE SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR OUR OCEAN WATERS FOR TODAY AND TONIGHT. THE ADVISORY IS MAINLY IN EFFECT FOR WAVE HEIGHTS AROUND 5 FEET. HOWEVER, LOCALIZED GUSTS NEAR 25 KNOTS ARE POSSIBLE. A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR DELAWARE BAY AND IT IS IN EFFECT UNTIL 600 PM. THE WIND DIRECTION IS FORECAST TO FAVOR THE SOUTHWEST FOR TODAY. A COLD FRONT FROM THE NORTH WILL DROP THROUGH THE REGION THIS EVENING AND THE WIND DIRECTION IS EXPECTED TO SHIFT TO THE NORTHWEST TO NORTHEAST QUADRANT. OUTLOOK... WEDNESDAY-SATURDAY...SUB-SMALL CRAFT ADVISORY CONDITIONS EXPECTED TO CONTINUE. WINDS COULD PERIODICALLY GUST AROUND 20 KNOTS, ESPECIALLY THURSDAY AND THURSDAY NIGHT WHEN GUSTS COULD APPROACH ADVISORY LEVELS.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT WEDNESDAY FOR ANZ450>455. SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ430- 431. && $$ SYNOPSIS...ROBERTSON NEAR TERM...IOVINO SHORT TERM...IOVINO LONG TERM...KLEIN AVIATION...IOVINO/ROBERTSON MARINE...IOVINO/ROBERTSON

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