Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 010150 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 950 PM EDT TUE JUN 30 2015 .SYNOPSIS... A TROUGH IS EXPECTED TO SLOWLY MOVE EAST THROUGH MID WEEK. AS IT DOES SO, A WARM FRONT WILL LIFT INTO OUR REGION TOMORROW, FOLLOWED BY A COLD FRONT LATE WEDNESDAY. THAT FRONT IS EXPECTED TO STALL JUST SOUTH OF OUR REGION FOR THE REMAINDER OF THE WORK WEEK. ANOTHER COLD FRONT COULD ARRIVE SATURDAY NIGHT. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... PWAT INCREASING TO 1.75 INCHES DELMARVA AND SE NJ TONIGHT. THATS HUMID AND ANY TSTMS CAN DUMP .50 INCHES IN 15 MINUTES FOR BRIEF POOR DRAINAGE FLOODING. STORMS MAY REORGANIZE INTO SUBSTANTIAL CLUSTERS AROUND ALONG THE WARM FRONT LATER THIS EVENING WITH WEAK LOW PRESSURE THE FOCUS. THIS PERMITS POTENTIAL FOR ORGANIZED STORMS FROM I95 SEWD IN THE 02Z-08Z TIME FRAME. A FLASH FLOOD WATCH CONTINUES IN EFFECT THRU 3 AM WED FOR PORTIONS OF ERN PA AND NORTHWESTERN NJ...WHERE CONVECTION CONTINUES TO REFORM AND TRAIN. PATCHY FOG AND STRATUS POSSIBLE TOWARD DAWN. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... GRADUALLY IMPROVING WEATHER...AS BOTH POPS AND SKY COVER DECREASE THROUGH THE DAY...WITH MAX TEMPS AOA AVG. ANY RESIDUAL SHOWERS AND SCT TSTMS IN NJ AND DE SHOULD END BY EARLY AFTN. PWAT DECREASES STEADILY DURING THE DAY. WEST TO SOUTHWEST WINDS GUST TO 20 MPH DURING THE AFTERNOON. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... LITTLE CHANGE TO THE LONG TERM IN ORDER TO FOCUS ON ONGOING SEVERE THREAT. PREVIOUS LONG TERM DISCUSSION...THERE WAS ABOUT A 50/50 SPLIT BETWEEN THE GFS AND WRF- NMMB INITIALIZATION AT 500MB. FARTHER DOWNWARD, THE WRF- NMMB LOOKED BETTER. DP/DTING THE WESTERN CONUS RIDGE LOOKS STRONGER, WHILE THE ERN NOAM TROF IS BROADER. WHILE THE MODELS AGREE ON A CONTINUATION OF THIS OVERALL SYNOPTIC PATTERN, THEY VARY ON DETAILS AND CONTINUE TO FIND THEMSELVES IN ODD POSITIONS WITH THE NORMALLY SLOWER ECMWF AND WRF-NMMB CONSIDERABLY FASTER THAN THE OTHER MEDIUM RANGE MODELS. AS PER PMDHMD WE ARE LEANING AWAY FROM THESE FASTER RESULTS AND GOING MORE TOWARD CONTINUITY. REGARDLESS WITH THE CURRENT PATTERN REMAINING IN PLACE IT IS TOUGH TO CONFIDENTLY PREDICT MUCH PROLONGED DRY WEATHER. THE START OF THE LONG TERM DOES HAVE DECENT MODELING CONSENSUS. WHILE THE WARM FRONT SHOULD BE LIFTING NORTHEAST OF OUR CWA, SHORT WAVES INTERACTING WITH THE WARM SECTOR SHOULD RE-GENERATE MORE SHOWERS AND TSTMS RATHER QUICKLY ON WEDNESDAY MORNING. COLD POCKET ALOFT COUPLED WITH NEAR NEUTRAL LOWER LEVEL THERMAL FIELDS KEEP PREDICTED TOTAL TOTALS AT OR AROUND 50C. APPROPRIATELY MIXED LAYER CAPES (ABOVE 1000J IN DELMARVA) PEAK DURING THE MORNING AND DECREASE AS THE AFTERNOON PROGRESSES AS THE COLD POCKET GETS SHEARED. HIGHEST POPS ARE IN THE MORNING WITH A TRAIL OFF AS THE DAY CONTINUES. STRONGER SHEAR AND CAPE ARE DECOUPLED AND (CAPE) MAY NOT RAMP UP FAST ENOUGH GIVEN TIMING OF FEATURES FOR SEVERE WHICH LOOKS BETTER NORTHEAST OF OUR CWA. AIR MASS SUPPORTIVE OF MID TO UPPER 80S FOR MAX TEMPS MOST OF OUR CWA. GIVEN THE BRIEF FLATTENING OF THE TROF ALOFT, WE DID NOT CARRY MUCH OF A CHANCE OF THUNDER INTO THE NIGHT AND NO POPS ANYWHERE OVERNIGHT. STAT GUIDANCE MINS LOOK REASONABLE. ON THURSDAY THE FRONTAL BOUNDARY IS EXPECTED TO STALL JUST SOUTH OF OUR CWA. FROM HERE THE TIMING OF IMPULSES ON THE FRONT START TO DIVERGE. REGARDLESS, THE BOUNDARY IS CLOSE ENOUGH TO ACT AS A TRIGGER WITH HIGHER CONFIDENCE (THUS HIGHER POPS) IN THE SOUTHEASTERN PART OF UR CWA. MIXED LAYER CAPES IN DELMARVA REACH THE LOWER 1000S, BUT ARE RELATIVELY LOW FARTHER TO THE NORTHWEST. THUNDER CHANCES MAY BE OVERSTATED. THERMAL FIELDS SUGGEST A 2-3F DROP OFF IN MAX TEMPS FROM WED. NOW THE MODELS REALLY START DIVERGING FOR THURSDAY NIGHT AND FRIDAY WITH THE GFS AND CAN GGEM EMPHASIZING FRIDAY WITH THE ECMWF AND WRF THURSDAY NIGHT. WHERE MODELS AGREE IS THAT INSTABILITY IN OUR CWA IS MODEST AND THERE ARE HIGHER CHANCES SOUTH THAN NORTH. TIMING RESOLUTION IS TOO UNCERTAIN TO FORECAST DRY WEATHER FOR EITHER PERIOD. WE DID STEER HIGHER POPS INTO THURSDAY NIGHT AS THE GEFS IS SLIGHTLY FASTER THAN THE OP GFS. IT DOES NOT BECOME MUCH CLEARER FOR INDEPENDENCE DAY WITH THE ECMWF FORECASTING A DRY DAY AND THE CAN GGEM HAVING A TOTAL WASHOUT. MOST MODELS ARE NOT INDICATING A SFC LOW ON THE LEVEL OF LAST SATURDAY, SO FOR NOW WE KEPT THE FORECAST FOR INDEPENDENCE DAY CLOSE TO CONTINUITY AND SUMMER CLIMO AND NOT SOUND LIKE A TOTAL LOSS. SUNDAY/MONDAY REMAIN CLOSE TO CONTINUITY. WITH BOTH THE GFS AND EC DRY WE HAVE SUNDAY PREDICTED TO BE THE BETTER OF THE TWO WEEKEND DAYS AND KEPT THE CHANCE FOR THUNDERSTORMS IN FOR MONDAY AS THE WARM FRONT IS PREDICTED TO RETURN. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. OVERNIGHT...MAINLY VFR SCT-BKN AOA 5000 FT BUT WITH PATCHES OF MVFR CIGS. BRIEF GUSTY WINDS TO 30-35 KT IN IFR TSTMS THROUGH 08Z. SE TO SSW FLOW NORTH TO SOUTH THROUGH THE WARM FRONTAL BOUNDARY. POSSIBLE DEVELOPING EXPANDING PATCHES IFR FOG/STRATUS AFTER 08Z IF THE SHOWERS DISSIPATE. PLS SEE TAFS AND OBSERVATIONS FOR DETAILS. WEDNESDAY...VFR SCT AOA 5000 FT WITH CHANCE OF LEFTOVER SHOWERS AND ISOLATED TSTMS IN THE MORNING TO EARLY AFTN HRS NJ/DE. WINDS BECOME WEST TO SOUTHWEST AND MAY GUST TO 20 KT DURING THE AFTERNOON. OUTLOOK... WEDNESDAY NIGHT...MOSTLY VFR WITH ANY PCPN CHANCES DECREASING QUICKLY. THURSDAY THROUGH SATURDAY...PREDOMINATELY VFR, BUT SOME MVFR OR IFR CONDITIONS DURING SCATTERED SHOWERS AND THUNDERSTORMS. IMPACT OUTLOOKED TO BE GREATER FOR SOUTHERN AIRPORTS AND TERMINALS. && .MARINE... SCA FOR DE BAY DISCONTINUED THIS EVENING. MAY NEED TO ADD SCA FOR HAZ 5 FT SEAS FOR A FEW HOURS DURING THE EARLY MORNING HOURS ALONG THE ATLC COAST, ESPECIALLY S NJ AND DE COASTS. OUTLOOK... WEDNESDAY NIGHT...SEAS ON THE OCEAN MAY APPROACH SMALL CRAFT ADVISORY CRITERIA IN PRE FRONTAL SOUTHERLY FLOW, BUT THERE IS CONSIDERABLE UNCERTAINTY. THURSDAY AND THURSDAY NIGHT...WINDS AND SEAS SHOULD REMAIN BELOW SCA CRITERIA. FRIDAY THROUGH SATURDAY...SEAS ON THE SOUTHERN OCEAN WATERS MIGHT REACH SMALL CRAFT ADVISORY LEVELS PENDING THE STRENGTH OF THE LOW PRESSURE SYSTEM ON THE FRONTAL BOUNDARY. CONFIDENCE IS LESS THAN AVERAGE. && .RIP CURRENTS... BASED ON OUR LOCAL FORECAST APPLICATION USING A 4 FOOT SWELL/7 SECOND PERIOD AND SOUTHWEST WIND AROUND 11 KNOTS, WE CONTINUE WITH A MODERATE RISK OF RIP CURRENTS FOR NEW JERSEY AND LOW RISK FOR DELAWARE WEDNESDAY. && .CLIMATE... KPHL TIP BUCKET NOT WORKING AND TRACE RAIN IS INCORRECT THIS EVENING. POSSIBLY OVER AN INCH. WE`LL ESTIMATE TODAY. THE CHART BELOW SHOWS RAINFALL STATISTICS AT OUR FOUR BIG CLIMATE SITES THRU 6/29. THE COLUMNS ARE BROKEN DOWN BY SITE, "POR" (HOW FAR RECORDS DATE BACK), JUNE 2015 RAINFALL, NORMAL JUNE RAINFALL, JUNE 2015 RAINFALL RANKING, AS WELL AS THE WETTEST JUNE ON RECORD. SITE POR JUNE NORMAL RANK WETTEST ILG 1894 12.46 3.50 2ND 13.66 (2013) ACY 1874 8.04 2.81 2ND 8.45 (1920) ABE 1922 7.02 3.86 6TH 10.51 (1938) PHL 1872 7.23 3.08 10TH 10.56 (2013) AT THIS TIME, IT HAS BEEN THE SECOND WETTEST JUNE ON RECORD IN BOTH WILMINGTON AND ATLANTIC CITY. WITH ONLY TODAY LEFT IN THE MONTH, CURRENT FORECASTS DO NOT FAVOR EITHER SITE BREAKING THEIR ALL-TIME JUNE RAINFALL RECORD. HOWEVER, IT WOULD ONLY TAKE A HEAVY SHOWER OR THUNDERSTORM TO CLOSE THE GAP, WHICH IS 0.41 INCHES IN ATLANTIC CITY AND 1.2 INCHES IN WILMINGTON. && .EQUIPMENT... KPHL TIP BUCKET ERRONEOUS AND TICKET OUT ON IT. WILL BE FIXED WEDNESDAY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...FLASH FLOOD WATCH UNTIL 3 AM EDT WEDNESDAY FOR PAZ054-055- 060>062-101-103-105. NJ...FLASH FLOOD WATCH UNTIL 3 AM EDT WEDNESDAY FOR NJZ001-007>009. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...GIGI NEAR TERM...DRAG 950 SHORT TERM...FRANCK LONG TERM...GIGI/JOHNSON AVIATION...DRAG/GIGI 950 MARINE...DRAG/GIGI 950 RIP CURRENTS... CLIMATE... EQUIPMENT...

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