Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 300105 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 905 PM EDT MON JUN 29 2015 .SYNOPSIS... A TROUGH IS EXPECTED TO SLOWLY PROPAGATE EAST THROUGH MID WEEK. AS IT DOES SO, A WARM FRONT WILL LIFT INTO OUR REGION TUESDAY, FOLLOWED BY A SLOW MOVING COLD FRONTAL PASSAGE LATE WEDNESDAY OR THURSDAY. 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 TUESDAY MORNING/... 630 PM ESTF ADJUSTED TEMPS HIGHER THROUGH SUNSET THEN DROPPED TEMPS A BIT FASTER UNDER CLEAR SKY LIGHT WIND LATE THIS EVENING BEFORE LEVELING WITH THE APPROACHING MID DECK CLOUD LAYER NOW CROSSING THE APPALACHIANS AT 00Z/30. SPRINKLES POSSIBLE FROM THE MID DECK CLOUD COVER IN E PA AFTER 08Z/30. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
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INTERESTING DAY SHAPING UP TOMORROW AS S/WV ENERGY TRAVERSING THE GREAT LAKES TROUGH LEADS TO SFC LOW DEVELOPMENT OVER LAKE ERIE...AS A WARM FRONT SLOWLY MOVES THRU REGION. MAIN CONCERN IS CONVECTIVE POTENTIAL DURING TOMORROW AFTERNOON AND EVENING. THE BEST CHANCES ARE GENERALLY NW OF I-95...WHERE ML CAPE NEAR 1000J AND BULK SHEAR VALUES OF 30 TO 40 KNOTS COINCIDE. EXPECT CONSIDERABLE CLOUDS OVR ERN PA AND NRN NJ...WHICH MAY LIMIT SVR POTENTIAL. SOME MODEL GUIDANCE SUGGESTS IT MIGHT BE PARTLY SUNNY INSTEAD OF MO CLOUDY. THE MAIN THREAT FROM TSTMS WOULD BE GUSTY WINDS AND SMALL HAIL...W/ INVERTED-V PROFILES AND FALLING WET BULB ZERO HEIGHTS. THERE IS ALSO A CONSIDERABLE AMOUNT HELICITY INVOF THE WARM FRONTAL BOUNDARY...SO CANNOT RULE OUT A SUPERCELL...IF ENOUGH INSTABILITY IS PRESENT. HWO: ADDED STRONG TSTM THREAT TO THE DELMARVA AND S NJ WHERE THE RECENT MULTI MODEL GUIDANCE LOOKS LIKE ITS CONCENTRATING GREATER AND DEEPER INSTABILITY VIA KI/TT/SWI AND MLCAPE PROJECTIONS, ESPECIALLY AFTER 00Z/01.
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&& .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... MODELS CONTINUE TO SHOW A GRADUAL TRANSITION FROM THE MOSTLY MERIDIONAL PATTERN WE HAVE CURRENTLY TO UPPER LEVEL ZONAL PATTERN BY NEXT WEEKEND. TOMORROW NIGHT...THE VORT MAX IN THE LEE OF THE UPPER LEVEL TROUGH PROPAGATES OVER OUR REGION, BRINGING INCREASING RAIN CHANCES. ONE FACTOR THAT MAY SLIGHTLY INHIBIT COVERAGE OF CONVECTION WILL BE A STABILIZING BOUNDARY LAYER RESULTING IN LARGE VALUES OF CIN. OTHERWISE, MODEST CAPE VALUES FOR ELEVATED PARCELS (AT LAYERS ABOVE 900 MB) AND BULK SHEAR VALUES OF 20 TO 30 KT, COMBINED WITH THE UPPER LEVEL SUPPORT SHOULD BE ENOUGH TO SUPPORT SUSTAINED UPDRAFTS AND A MARGINAL THREAT FOR SMALL HAIL OR GUSTY WINDS. WEDNESDAY...DEPENDING ON HOW QUICKLY THE SURFACE LOW LIFTS AWAY, THERE MAY BE A BIT OF A LULL IN THE PRECIP, ESPECIALLY EARLY IN THE DAY. HOWEVER, GIVEN THE UNCERTAINTY IF A MID LEVEL TROUGH WILL LIFT OVER THE REGION, KEPT MENTION OF CHANCE POPS THROUGH THE DAY. BY LATE IN THE DAY, HOWEVER, ATTENTION WILL TURN TO THE NEXT COLD FRONT DUE TO ARRIVE EITHER WEDNESDAY EVENING OR LATE WEDNESDAY NIGHT. ISENTROPIC LIFT SHOULD BE SUFFICIENT FOR ANOTHER ROUND OF SHOWERS AND STORMS WITH THE FRONT. THURSDAY AND FRIDAY...THE BIG QUESTION ON THESE DAYS WILL BE HOW FAR SOUTH THE FRONT WILL STALL. LATEST RUNS OF BOTH THE GFS AND ECMWF HAVE THE FRONT STALLING A BIT FURTHER SOUTH THAN PREVIOUS RUNS, THUS GIVING OUR REGION ANOTHER LULL IN PRECIP CHANCES. HOWEVER, STAYED CLOSE TO THE PREVIOUS FORECAST AS I AM NOT CONFIDENT THIS TREND WILL HOLD GIVEN A FLATTENING TROUGH. SATURDAY...IN THE WAKE OF ONE FRONT, WE COULD HAVE ANOTHER COLD FRONT RIGHT ON ITS HEELS. HAVE KEPT THE MENTION OF CHANCE POPS, BUT AGREE WITH THE PREVIOUS SHIFT THAT IT APPEARS TO BE ONLY A BRIEF OPPORTUNITY FOR ANY RAIN. SUNDAY CONTINUES TO LOOK DRY AS WE COULD EVEN HAVE AN UPPER LEVEL SHORT WAVE RIDGE SLIDING EAST OVER OUR REGION AT THAT TIME. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. OVERNIGHT...VFR CLEAR THEN CIGS AOA 7000 FT INVADING FROM WEST TO EAST. LIGHT SW TO S WIND. PLEASE SEE TAF FOR DETAILS. TUESDAY...SCT-BKN AOA 5000 FT. S WIND GUST 15-20 KT DURING THE AFTN. SCT SHOWERS E PA DURING THE MORNING THEN TSTMS EXPECTED TO DEVELOP AND ROLL NEWD TUE AFTN. STRONGEST STORMS KRDG TO THE DELMARVA WHERE THEY SHOULD PRODUCE A FEW GUSTS 30-40 KT. OUTLOOK... TUESDAY NIGHT THROUGH WEDNESDAY...MAINLY VFR EXCEPT MVFR OR IFR CONDITIONS WITH SCATTERED SHOWERS AND STORMS WEDNESDAY NIGHT...MOSTLY VFR WITH SHOWER CHANCES DECREASING. THURSDAY THROUGH SATURDAY...MOSTLY VFR EXCEPT MVFR OR IFR WITH SHOWERS AND THUNDERSTORMS.
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&& .MARINE...
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WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SCA CRITERIA TONIGHT AND TUESDAY. OUTLOOK... TUESDAY NIGHT INTO WEDNESDAY...SEAS MAY APPROACH 5 FT, BUT THERE IS CONSIDERABLE UNCERTAINTY. THURSDAY THROUGH SATURDAY...WINDS AND SEAS SHOULD REMAIN BELOW SCA CRITERIA.
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&& .RIP CURRENTS...
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TUESDAY: LOW RISK DE BUT MDT RISK NJ. USED 3 FT 8 SEC AND A SE WIND 12 KT. LOCAL AP GAVE LOW RISK EVERYWHERE BUT WITH FULL MOON JULY 1, RAISED THE RISK JUST INTO THE MDT RANGE FOR NJ. TIDE WILL BE TURNING AROUND AND COMING IN DURING THE AFTERNOON SO THAT MAY LOWER THE RISK SLIGHTLY?. WHAT WE DO KNOW IS THAT SSTS LOOK LIKE THEY ARE RUNNING 2 TO 4F DEGREES ABOVE NORMAL WITH VERY LITTLE UPWELLING PRESENT...VERY UNIFORM SST FROM NORTH TO SOUTH ALONG OUR MID ATLANTIC COASTS. THERE MAY BE A LITTLE MORE SUNSHINE THAN CURRENTLY FORECAST AND ANY TSTMS SHOULD BE DELAYED TIL AROUND 5P OR AFTER. SAFEST SWIMMING IS TO BE FOUND IN THE PRESENCE OF LIFEGUARDS. JETTY, PIER AND GROYNE (GROIN) SWIMMING IS RISKY AND FRAUGHT WITH GREATER DANGERS ASSOCIATED WITH RECURRENT RIP CURRENTS THERE.
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&& .CLIMATE... THE CHART BELOW SHOWS RAINFALL STATISTICS AT OUR FOUR BIG CLIMATE SITES THRU NOON 6/28. THE COLUMNS ARE BROKEN DOWN BY SITE, "POR" (HOW FAR RECORDS DATE BACK), 6/27 RAINFALL, JUNE 2015 RAINFALL, NORMAL JUNE RAINFALL, JUNE 2015 RAINFALL RANKING, AS WELL AS THE WETTEST JUNE ON RECORD. SITE POR 6/27 JUNE NORMAL RANK WETTEST ILG 1894 2.17 12.46 3.50 2ND 13.66 (2013) ACY 1874 2.37* 8.04 2.81 2ND 8.45 (1920) ABE 1922 0.86 7.02 3.86 6TH 10.51 (1938) PHL 1872 1.34 7.23 3.08 10TH 10.56 (2013) *ATLANTIC CITY BROKE THEIR DAILY RAINFALL RECORD OF 1.74" IN 1912 AT THIS TIME, IT HAS BEEN THE SECOND WETTEST JUNE ON RECORD IN BOTH WILMINGTON AND ATLANTIC CITY. WITH ONLY ONE DAY 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. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...JOHNSON/DRAG NEAR TERM...DRAG 904 SHORT TERM...DRAG/FRANCK LONG TERM...JOHNSON AVIATION...DRAG/JOHNSON 904 MARINE...FRANCK/JOHNSON RIP CURRENTS...DRAG 904 CLIMATE...

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