Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 231000 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 600 AM EDT SAT MAY 23 2015 .SYNOPSIS... STRONG HIGH PRESSURE OVER PENNSYLVANIA WILL MOVE OFF THE MID ATLANTIC COAST TONIGHT AND REMAIN CENTERED IN THE CENTRAL ATLANTIC OCEAN THIS COMING WEEK. A WARM FRONT WILL PASS NORTHWARD THROUGH OUR REGION ON MONDAY. A VERY WEAK COOL FRONT WILL DRIFT EAST INTO THE MID ATLANTIC STATES LATE THIS COMING WEEK AND DISSIPATE BY NEXT WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A TRANQUIL DAY IS IN STORE FOR THE REGION WITH MASSIVE AMOUNTS OF SUBSIDENCE TAKING PLACE. LOOKING AT FORECAST SOUNDINGS FOR THIS AFTERNOON, OUR PWATS MAY REACH DAILY MINIMUMS IN A LOT PLACES BASED OFF OF SPC`S SOUNDING CLIMATOLOGY FOR OKX/LWX...DRY BEGETS DRY. DEWPOINTS SHOULD BOTTOM OUT IN THE MID TO UPPER-20S THIS AFTERNOON EVEN THOUGH MIXING WILL NOT BE NEARLY AS STRONG/HIGH AS IT WAS ON FRIDAY...NOT EXPECTING MUCH IN THE WAY OF GUSTS. THERMALLY BOTH THE NAM AND GFS WERE A TOUCH TOO COLD AT 850/925MB FOR THEIR 23/00Z INITIALIZATION. THE LOWERING SUBSIDENCE INVERSION WILL LIMIT THE AMOUNT OF VERTICAL MIXING, AS STATED ABOVE, BUT WITH MORE THAN ENOUGH SUNSHINE AND THE SURFACE FLOW BACKING TOWARDS THE WEST, WE WENT A COUPLE DEGREES ABOVE GUIDANCE...STILL KEEPS US BELOW NORMAL FOR THE DAY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/... THE SURFACE RIDGING SLIDES A BIT FARTHER TO OUR SOUTH AND EAST AS THE SURFACE FLOW BACKS FARTHER TOWARDS THE SOUTHWEST. DO NOT THINK WE COMPLETELY LOSE THE WINDS TONIGHT AND THERE COULD BE SOME HIGH BASED CLOUDS STREAMING IN FROM THE SOUTHWEST SO HAVE KEPT CLOSE TO GUIDANCE TONIGHT BUT WENT SLIGHTLY COOLER IN THE PINE BARRENS...NOT THINKING FROST WILL BE AN ISSUE. AN INCREASE IN DEWPOINT TEMPERATURES WILL ALSO KEEP TEMPERATURES FROM FALLING OFF THE TABLE TONIGHT, THOUGH THEY MAY DROP QUICKLY AFTER SUNSET, ONCE WE LOSE THE BETTER MIXING. && .LONG TERM /SUNDAY THROUGH FRIDAY/... **FIRST HEAT WAVE OF THE SEASON MAY DEVELOP FOR THE I-95 CORRIDOR THIS COMING WEEK** 500 MB: A STRONG RIDGE SUMMERTIME RIDGE DEVELOPS ALONG THE EAST COAST IN THIS FORECAST PERIOD. TEMPERATURES: THE FIRST 22 DAYS OF MAY HAS AVERAGED 5 TO 6 DEGREES ABOVE NORMAL IN OUR FORECAST AREA AND DESPITE TODAYS COLD SHOT THE MONTH AS A WHOLE SHOULD AVERAGE 6 TO 7 DEGREES ABOVE NORMAL, PLACING IT EASILY IN THE TOP 10 WARMEST MONTHS OF MAY ON RECORD, AGAIN IN OUR AREA. IT MOST LIKELY WILL BE A TOP 3 FINISHER AT LEAST IN PHILADELPHIA AND ALLENTOWN. THE DAILY AVERAGE ON SUNDAY WILL STILL BE SEVERAL DEGREES BELOW NORMAL BECAUSE OF THE CHILLY START, THEN IT WARMS TO AROUND 5 DEGREES ABOVE NORMAL ON MEMORIAL DAY AND CALENDAR DAY AVERAGES THEREAFTER THE REST OF THE COMING WEEK WILL BE 6 TO 12 DEGREES ABOVE NORMAL, EVERY DAY. QPF: A BASICALLY RAINFREE 6 DAY PERIOD IS EXPECTED ALONG THE COAST WITH I-95 NWWD RAINFALL CONTINGENT ON A WEAKENING COLD FRONT MOVING TO NEAR I-95 LATE THIS COMING WEEK. IF THE RIDGE ALOFT PREVENTS IT FROM DRIFTING THIS FAR EAST, THE ENTIRE CWA WOULD BE BASICALLY RAINFREE THIS ENTIRE 6 DAY EXTENDED FORECAST PERIOD. FOR NOW, WE ACCEPTED THE ECMWF POTENTIAL FOR THURSDAY-FRIDAY HOWEVER CONFIDENCE ON EASTWARD EXTENT INTO OUR FORECAST AREA IS BELOW AVERAGE AS OF THIS WRITING. FORECAST BASIS: UNLESS OTHERWISE NOTED, A 50 50 BLEND 00Z/23 GFS/NAM MOS GUIDANCE SUNDAY - MONDAY, 00Z/23 MEX MOS MONDAY NIGHT AND TUESDAY, THEN THE 0541Z/23 WPC GRIDDED ELEMENTS OF MAX/MIN TEMP, 12 HOUR POP, 6 HOUR DEWPOINT-SKY-WIND FROM TUESDAY NIGHT THROUGH NEXT SATURDAY? HAZARDS: CONTINUING THE MOUNT HOLLY PHILOSOPHY FROM YESTERDAY... THIS FORECAST IS WEIGHED MORE ON THE ECMWF OPERATIONAL RUNS AND IT`S SOMEWHAT WARMER RESPECTIVE ENSEMBLE MEAN. THERE IS A CHANCE THAT AN EARLY SEASON LOWER CRITERIA (96F HEAT INDEX) HEAT ADVISORY WILL NEED TO BE ISSUED WEDNESDAY FOR THE WILMINGTON- PHILADELPHIA- TRENTON CORRIDOR. THE DAILIES... CONFIDENCE ON THE GENERAL FORECAST THIS ENTIRE 6 DAY PERIOD IS ABOVE AVERAGE EXCEPT WHERE EXPRESSLY NOTED BELOW. SUNDAY...M/S. SW WIND WITH GUSTS TO 15 MPH DURING THE AFTERNOON. SUNDAY NIGHT...FAIR. MID DECK WAA CLOUDS TOWARD DAWN. LIGHT SW WIND. MONDAY...AFTER CONSIDERABLE WAA MORNING CLOUDINESS IT BECOMES P TO M/SUNNY. SW WIND GUSTS 15-20 MPH DURING THE AFTERNOON. TUESDAY...P-M/S. SW WIND GUSTS TO 25 MPH DURING THE AFTERNOON. MINIMAL SHOWER RISK LATE IN THE POCONOS. WEDNESDAY...P-M/S. SW WIND GUSTS TO 25 MPH DURING THE AFTERNOON. A SOMEWHAT BETTER CHANCE OF TSTMS IN A HOTTER-MORE UNSTABLE ENVIRONMENT OVER E PA AND NW NJ BUT CONFIDENCE IS BELOW AVG. THURSDAY AND FRIDAY...P-M/S. A LITTLE MORE SOUTHERLY COMPONENT TO THE WIND AND MAX GUSTS UNDER 20 MPH. CHANCE OF SHOWERS AND TSTMS WITH A SLOWLY WEAKENING COOL FRONT DRIFTING EAST INTO OUR AREA. CONFIDENCE ON WHETHER THAT FRONT MAKES IT THIS FAR EAST IS BELOW AVERAGE. PWAT NEAR 1.75 INCHES, IMPLYING IF THE LIFT MECHANISM ARRIVES IN THIS SUMMERTIME AIRMASS, IT WILL RELEASE HEAVY RAINS. WITH LIGHTER WINDS AND HIGHER HUMIDITY, PATCHY FOG PROBABLY DEVELOPS LATE EACH NIGHT. && .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY - TONIGHT...VFR. NORTHERLY WINDS TO START THE DAY WILL BACK TOWARDS THE WEST BY THE EARLY AFTERNOON AS HIGH PRESSURE SETTLES IN...LESS THAN 10 KNOTS. SEA BREEZE IS EXPECTED TO PUSH THROUGH ACY BY MID-AFTERNOON. WINDS BACK FARTHER TOWARDS SOUTHWEST TONIGHT BECOMING LIGHTER. OUTLOOK... SUNDAY: VFR, SOUTHWEST WINDS GUST 15 KT DURING THE AFTERNOON. WAA MID DECK OVC MAY DEVELOP TOWARD SUNRISE MONDAY. MONDAY THROUGH WEDNESDAY: VFR, WITH SOME LOWER RESTRICTIONS POSSIBLE IN ANY LATE AFTERNOON SHOWERS OR TSTORMS TUESDAY AND WEDNESDAY VCNTY KABE/KRDG ONLY. SOUTH TO SOUTHWEST WINDS WITH GUSTS AROUND 20 KNOTS EACH AFTERNOON. && .MARINE... TODAY - TONIGHT...WE CANCELED THE SCA FOR THIS MORNING AS THE WINDS SHOULD BE DECREASING AS THE MORNING WEARS ON. OTHERWISE, SUB-SCA CONDITIONS EXPECTED TODAY AND TONIGHT WITH HIGH PRESSURE SITTING OVERHEAD. NORTHERLY WINDS TO START WILL BACK TOWARDS THE WEST AND THEN SOUTHWEST BY LATE TONIGHT AND BECOMING LIGHTER WITH THE HIGH SHIFTING A BIT TOWARDS THE EAST. OUTLOOK... THROUGH WEDNESDAY...SEAS AND WINDS ARE EXPECTED TO REMAIN BELOW SCA CRITERIA. WINDS WILL BE OUT OF THE SOUTH TO SOUTHWEST WITH SOME WIND GUSTS AROUND 20 KNOTS. && .RIP CURRENTS... POTENTIAL HEAT WAVE NEXT WEEK. THIS PLUS WATER TEMPS CONTINUING ABOVE NORMAL IS NOT GOOD FOR SAFETY. ONCE IT TURNS HOT AND BEACHES ARE UNGUARDED, SWIMMERS MAY TAKE CHANCES AT UNGUARDED LOCATIONS. BE SMART ABOUT ANY SWIMMING EARLY THIS SEASON. RIP CURRENT AWARENESS WEEK FOR MT HOLLY IS JUNE 7-13 WITH PSAS VIA PUBLIC INFORMATION STATEMENTS, SOCIAL MEDIA, NOAA WEATHER RADIO AND ANY MEDIA INTERVIEWS DESIRED (CONTACT OFFICE). FOR RIP CURRENTS: DESPITE ANTICIPATED PROJECTIONS OF LOW OR MODERATE RISK THROUGH THE MEMORIAL DAY WEEKEND, EARLY SEASON FATALITIES OCCUR WHEN SWIMMING AT UNGUARDED TIMES/LOCATIONS. WEAKER SWIMMERS OR SWIMMING IN AREAS WHERE RIP CURRENTS ARE STRONGER (JETTIES) CAN QUICKLY BECOME LIFE THREATENING. WHEN TRAINED LIFEGUARDS ARE NOT NEARBY, TIMELY RESCUE IS MUCH LESS LIKELY. LETS GET THROUGH THE MONTH OF MAY WITH ALL SWIMMERS SAFE! PLEASE BROADCAST THIS MESSAGE: FOR ULTIMATE SAFETY, ALWAYS SWIM IN THE PRESENCE OF LIFE GUARDS! THANK YOU! && .CLIMATE... **A TOP 10 WARMEST MAY WILL OCCUR IN LARGE PORTIONS OF OUR FORECAST AREA AND LESSENING DOUBT FOR A TOP 3 WARMEST KABE/KPHL** UPDATED AT 510 AM THIS SATURDAY MORNING: THE FIRST 22 DAYS OF MAY IN OUR FORECAST AREA WERE AVERAGING ABOUT 5 TO 6 DEGREES ABOVE NORMAL. RUNNING THE NUMBERS FROM THIS MORNINGS 330AM FCST THROUGH THE END OF THE MONTH WE FIND THE FOLLOWING. FOR PHILADELPHIA...PERIOD OF RECORD (POR) BACK TO 1874. PROJECTING A MONTHLY AVERAGE TEMPERATURE OF 69 TO 70, AT LEAST 5 TO 6 DEGREES ABOVE NORMAL. HEADING FOR SECOND OR THIRD WARMEST ON RECORD. WARMEST WAS 70.8 IN 1991. THEN 69.2 2004. FOR ALLENTOWN...PERIOD OF RECORD (POR) BACK TO 1922. PROJECTING 66.5 OR ABOUT 6.5 DEGREES ABOVE NORMAL WHICH WOULD BE 2ND OR 3RD WARMEST ON RECORD. 1991 WAS THE WARMEST WITH 67.2, FOLLOWED BY 2012 66.1, THEN 1944 WHEN MAY AVERAGED 66.0. THE FOLLOWING WAS POSTED BECAUSE ITS LIKELY THAT WE WILL EXPERIENCE OUR FIRST 90 IN PHILADELPHIA BY THE MIDDLE OF NEXT WEEK, AND POSSIBLY A HEAT WAVE. NORMAL FIRST DATE OF 90 OR HIGHER. PHILADELPHIA MAY 29 ALLENTOWN MAY 30 WILMINGTON JUNE 4 ATLANTIC CITY JUNE 11. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR PAZ054-055. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...DRAG NEAR TERM...HEAVENER SHORT TERM...HEAVENER LONG TERM...DRAG 559 AVIATION...DRAG/HEAVENER MARINE...DRAG/HEAVENER RIP CURRENTS... CLIMATE...559

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