Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 050800 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 400 AM EDT SUN JUL 5 2015 .SYNOPSIS... WEAK HIGH PRESSURE OVER THE MID ATLANTIC STATES MOVES OFFSHORE LATE TODAY. A WARM FRONT IS EXPECTED TO LIFT THROUGH OUR REGION TUESDAY MORNING. A WEAK COLD FRONT IS ANTICIPATED TO ARRIVE FROM THE NORTHWEST ON WEDNESDAY. THIS FRONT WILL REMAIN IN OR NEAR OUR REGION ON THURSDAY INTO FRIDAY WITH AN AREA OF LOW PRESSURE EXPECTED TO MOVE ALONG THE FRONT AT THAT TIME. WEAK HIGH PRESSURE SHOULD FOLLOW TO START NEXT WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... FAIR WEATHER WILL PREVAIL TODAY WITH WEAK HIGH PRESSURE AT THE SURFACE BUILDING ACROSS THE AREA THIS MORNING AND MOVING OFFSHORE THIS AFTN. THIS WILL RESULT IN LIGHT SFC WINDS TODAY ALSO. LOW CLOUDS FROM YDA HAVE BEEN SLOW TO CLEAR OVERNIGHT DUE TO THE LIGHT WINDS...ALTHO DRIER AIR ALOFT IS PUSHING IN FROM THE WEST. THE STRONG JULY SUN SHOULD BE ABLE TO DISSIPATE THESE CLOUDS BY MID TO LATE MORNING. WITH PLENTY OF SUNSHINE MAX TEMPS THIS AFTN SHOULD BE GENLY IN THE MID 80S...CLOSE TO NORMAL FOR THIS TIME OF YEAR. A GOOD SEA BREEZE IS EXPECTED TO DEVELOP THIS AFTERNOON AND PUSH WELL INLAND BY EARLY EVENING...WHICH WILL COOL THINGS OFF A BIT FOR AREAS CLOSER TO THE SHORE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... LOW PRES ALOFT...OVER MIDDLE TN EARLY THIS MORNG...WILL MOVE SLOWLY NEWD TOWARDS US TODAY AND TONIGHT. THIS WILL RESULT IN INCREASING SLY FLOW OVER THE MID-ATLANTIC REGION WITH A GRADUAL RETURN OF CLOUDS AND MOISTURE. THE MAIN EFFECT SHOULD BE MONDAY AND BEYOND BUT HAVE KEPT A SLGT CHANCE FOR SHOWERS LATE TONIGHT OVER DELMARVA. WINDS AT THE SFC WILL AGAIN BECOME RATHER LIGHT AND CLOUDS SHOULD NOT BE TOO THICK OR WIDESPREAD...SO OVERNIGHT MIN TEMPS SHOULD FALL INTO THE MID/UPPER 60S FOR MOST AREAS NORTH OF DELMARVA. && .LONG TERM /MONDAY THROUGH SATURDAY/... 500 MB: THE WEAK MID LEVEL LOW OVER WEST VIRGINIA MONDAY MORNING WEAKENS NORTHEASTWARD THROUGH THE MID ATLANTIC STATES TUESDAY. THEN A SEASONABLE SUMMERTIME WESTERLY FLOW OCCURS WEDNESDAY THROUGH NEXT WEEKEND, FRAUGHT WITH UNCERTAINTY REGARDING TIMING OF SHOWERS/TSTMS. TEMPERATURES: CALENDAR DAY AVERAGE TEMPERATURES WILL BE NEAR OR SLIGHTLY ABOVE NORMAL MONDAY, THEN AROUND 5 DEGREES ABOVE NORMAL TUESDAY AND WEDNESDAY WITH TEMPERATURES AT OR ABOVE NORMAL THURSDAY THROUGH NEXT WEEKEND. FORECAST BASIS: UNLESS OTHERWISE NOTED, A 50 50 BLEND 00Z/5 GFS/NAM MOS GUIDANCE MONDAY-TUESDAY, 00Z/5 MEX MOS TUESDAY NIGHT AND WEDNESDAY, THEN THE 0541Z/5 WPC GRIDDED ELEMENTS OF MAX/MIN TEMP, 12 HOUR POP, 6 HOUR DEWPOINT- SKY-WIND FROM WEDNESDAY NIGHT THROUGH NEXT SATURDAY. THE DAILIES BELOW... MONDAY...WARM AIR ADVECTION INSTABILITY BURST SHOWER/TSTM THREAT DEVELOPS FROM SSW TO NNE MONDAY AND MONDAY NIGHT, BEGINNING FIRST OVER MD`S E SHORE AND SPREADING NORTHWARD, PRIMARILY INTO E PA MON NIGHT. MONDAY DURING THE DAY FOR THE MOST PART SHOULD BE HALFWAY DECENT. CONSIDERABLE MORNING MID AND HIGH CLOUD THINS OUT DURING THE AFTERNOON. STRATUS AND/OR FOG APPEARS LIKELY LATE MONDAY NIGHT AHEAD OF THE WARM FRONT (DENSE FOG ADVISORY?). WIND MAINLY S-SE WITH MAX GUSTS 15 MPH. PWAT 1.5 INCHES AT PHL DAYBREAK MONDAY INCREASES TO 1.75 MONDAY NIGHT. 1000JML CAPE DURING THE DAYLIGHT HOURS MD E SHORE AND DE. CONFIDENCE: OVERALL AVERAGE THOUGH BELOW AVERAGE REGARDING AREAL COVERAGE OF SHOWERS. TUESDAY...PARTLY SUNNY, VERY WARM OR HOT, AND HUMID WITH A S-SW WIND AND MAX GUSTS 20 MPH. SCT SHOWERS AND TSTMS WITH BRIEF TORRENTIAL RAINS, MAINLY NE PA AND NNJ DURING THE DAY INTO THE EARLY EVENING THEN THE RAIN THREAT DIMINISHES OR ENDS TUESDAY NIGHT. 1000J MLCAPE, MAINLY NR I-95 KPHL NEWD. PWAT NEAR 1.5 TO 1.6 INCHES THROUGHOUT OUR FORECAST AREA. COOLING COASTAL SOUTHERLY SEABREEZES DURING THE DAY ALONG THE IMMEDIATE COASTS ONLY. CONFIDENCE: AVERAGE ON TEMPS AND BELOW AVERAGE AREAL COVERAGE OF TSTMS. ONE WOULD THINK THIS WARM SECTOR PATTERN SHOULD PRODUCE 90F HEAT IN THE I-95 CORRIDOR AND ALSO SOME TORRENTIAL DOWNPOURS IN TSTMS ASSOCIATED WITH THE LEFTOVER MID LVL COOL POOL PASSING THROUGH. RIGHT NOW, K INDEX FCSTS SUGGEST THUNDER CHANCES ARE BEST ALONG AND N OF I-78. WEDNESDAY...HOT AND HUMID WITH A GOOD CHANCE OF AFTN TORRENTIAL RAIN PRODUCING TSTMS ALONG A WEAK COLD FRONT. BEST CHC APPEARS TO BE I- 78 NORTHWARD. LESS THAN 1000J MLCAPE MAINLY I-78 NORTH. PATCHY FOG LATE WED NIGHT IN THE WEAK FRONTAL ZONE. SW WIND WITH MAX GUSTS 20 MPH TURN NW AT NIGHT. PWAT NEAR 1.7 INCHES TO START THE DAY. CONFIDENCE: AVERAGE, IN PART BECAUSE THE ECMWF IS NOT AS HOT AS I`D EXPECT WITH 17-18C AT 850MB. THURSDAY...LOW CONFIDENCE FOR THIS DAY OF THE FCST. A CONTINUED THREAT OF SHOWERS AND TSTMS SINCE THE FRONTAL BOUNDARY STALLS ALONG THE MASON DIXON LINE ALONG WITH CONSIDERABLE CLOUDINESS? STRATUS/FOG POSSIBLE LATE THU NIGHT ALONG WHAT MIGHT BE A WEAK BACK DOOR COLD FRONT I-78 NORTH. CONFIDENCE: BELOW AVERAGE. FRIDAY AND SATURDAY: FOLLOWED WPC GUIDANCE. LIGHT WIND. CONFIDENCE BELOW AVERAGE. && .AVIATION /08Z SUNDAY THROUGH THURSDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDS ARE NOTED EARLY THIS MORNING AT ALL OUR TAF SITES EXCEPT RDG. BEFORE SUNRISE SOME CIGS MAY FLIRT WITH MVFR BUT THEN A STRONG JUL SUN SHOULD DISSIPATE CLOUDS BY MID TO LATE MORNING. WINDS WILL BE LIGHT THIS MORNG AS WEAK SFC HIGH PRES MOVES ACROSS THE AREA... BUT BECOMING SLY THIS AFT AS THE HIGH MOVES OFFSHORE AND A SEA BREEZE PUSHES INLAND ACROSS NJ AND DE. VFR CONDS SHOULD ALSO CONTINUE THROUGH TONIGHT WITH LIGHT WINDS. OUTLOOK... MONDAY...MAINLY VFR SCT-BKN AOA 5000 FT. S-SE WIND MAX GUSTS 15 KT. CHANCE OF SHOWERS OR EVEN A TSTM FROM KILG THROUGH KPHL-KPNE-KRDG AND KABE. CONFIDENCE: AVERAGE MONDAY NIGHT AND TUESDAY MORNING...CONDITIONS PROBABLY LOWERING TO MVFR OR IFR IN LOW CLOUDS FOG BETWEEN 06Z-14Z/7. LIGHT SOUTH WIND. CONFIDENCE: ABOVE AVERAGE TUESDAY AFTERNOON AND TUESDAY EVENING...MAINLY VFR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS. GRADIENT SW WIND GUST 15-20 KT DURING THE AFTERNOON. CONFIDENCE: AVERAGE. TUESDAY NIGHT AND WEDNESDAY MORNING...CONDITIONS POSSIBLY LOWERING TO MVFR OR IFR IN LOW CLOUDS, HAZE AND FOG ESPECIALLY DURING THE LATE NIGHT AND EARLY MORNING HOURS. LOOKS A LOWER CHANCE OF IFR ST/FOG EARLY WEDNESDAY THAN THE PREVIOUS EARLY TUESDAY MORNING. CONFIDENCE: AVERAGE WEDNESDAY AFTERNOON THROUGH THURSDAY...SCATTERED SHOWERS AND THUNDERSTORMS POSSIBLY CAUSING CONDITIONS TO LOWER TO MVFR OR IFR AT TIMES. GRADIENT SW WIND PROBABLY GUSTS 15-20 KT DURING THE AFTERNOON. CONFIDENCE:AVERAGE. && .MARINE... GENLY LIGHT WINDS AND SEAS SHOULD PREVAIL THROUGH TODAY AND TONIGHT. SOMEWHAT STRONGER ONSHORE FLOW SHOULD DEVELOP THIS AFTERNOON ALONG WITH SLY WINDS BLOWING UP DEL BAY. HIGH PRES MOVING OFFSHORE BY LATE TODAY WILL HELP MAINTAIN A SLY TO SELY FLOW OVERNIGHT. OUTLOOK... MONDAY THROUGH THURSDAY...NO MARINE HEADLINES ARE ANTICIPATED. THERE IS A SMALL CHANCE AN SCA MIGHT BE NEEDED FOR ATLANTIC SEAS LATE TUESDAY BUT THE PROBABILITY AT THIS TIME IS LOW. && .RIP CURRENTS... A MODERATE RISK FOR THE DEVELOPMENT OF DANGEROUS RIP CURRENTS CONTINUES TODAY FOR THE NEW JERSEY COAST. THIS IS DUE TO AN ONSHORE FLOW WHICH IS ON THE LIGHT SIDE HOWEVER IT SHOULD BECOME MORE SOUTHEASTERLY, ESPECIALLY DURING THIS AFTERNOON. THIS MAY RESULT IN SOME ENHANCED RIP CURRENT DEVELOPMENT DUE TO THE ANGLE OF INCIDENCE ALONG THE NJ COAST. OTHERWISE, A LOW RISK IS MAINTAINED FOR THE DELAWARE BEACHES. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...DRAG 4A NEAR TERM...AMC 4A SHORT TERM...AMC 4A LONG TERM...DRAG 4A AVIATION...AMC/DRAG 4A MARINE...AMC/DRAG 4A RIP CURRENTS...4A

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