Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 221524 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1124 AM EDT FRI MAY 22 2015 .SYNOPSIS... A COLD FRONT WILL CROSS OUR REGION LATER THIS AFTERNOON, THEN HIGH PRESSURE BUILDS IN SATURDAY BEFORE SHIFTING OFFSHORE SATURDAY NIGHT AND SUNDAY. A WARM FRONT IS FORECAST TO LIFT NORTH ACROSS OUR AREA DURING MONDAY. A COLD FRONT IS THEN ANTICIPATED TO REMAIN WELL TO OUR NORTH AND WEST WEDNESDAY AND THURSDAY AS HIGH PRESSURE REMAINS ANCHORED IN THE WESTERN ATLANTIC. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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NO CHANGES TO THE OVERALL FORECAST FOR TODAY. MOSTLY SUNNY SKIES THIS MORNING WILL BECOME PARTLY CLOUDY BY THIS AFTERNOON AS A MOSTLY DRY COLD FRONT SWEEPS THROUGH THE AREA. MODELS, ESPECIALLY THE HRRR, DO SHOW AN ISOLATED SHOWER OR SPRINKLE MOVING ACROSS THE AREA THIS AFTERNOON BETWEEN 2-6 PM, BUT MOST PLACES SHOULD REMAIN PRECIPITATION FREE. WIND GUSTS ARE BEGINNING TO INCREASE INTO THE LOW 20S, AND SHOULD REACH THE 25-35 MPH RANGE BY THIS AFTERNOON. WEST WINDS WILL BECOME NORTHWEST BEHIND THE FRONT LATER THIS AFTERNOON/EARLY EVENING. TEMPS REBOUND AFTER YDYS 12 TO 18 BELOW NORMAL MAX TEMPS WITH THIS AFTNS TEMPS ABOUT 15-20 DEGREES WARMER COMPARED TO THURSDAY AFTN (NEAR NORMAL MAX`S). FORECAST GENERATED GENERALLY FROM A 5050 BLEND OF 00Z/22 NCEP MOS GUIDANCE (GFS/NAM). CONFIDENCE: ABOVE AVERAGE.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... CLEAR AND TURNING CHILLY AS THE CFP NEAR I-80 (NE PA/NNJ) IN THE 6P TIME FRAME SLIPS DOWN TO VCNTY KACY-KPHL AROUND 11P WITH A PERIOD OF GUSTY NORTH-NORTHWEST WINDS OF 20-25 MPH EXPECTED EARLY AT NIGHT THEN DECOUPLING-RAPIDLY DIMINISHING WIND LATE AS TEMPS FALL RAPIDLY. WILL CONTINUE A TOUCH OF SCT FROST FROM WARREN-SUSSEX COUNTIES IN NW NJ INTO MONROE AND CARBON COUNTIES OF NE PA. JUST NOT ENOUGH COVERAGE EXPECTED FOR A FROST ADVY. ALSO WITH FULL GREENUP, PROBABLY ENOUGH LEAF COVER TO PREVENT MUCH DAMAGE. STILL, CANT BE ABSOLUTELY SURE AND SO PATCHY FROST IS IN THE FCST AND POSSIBLE SPS MATERIAL LATER TODAY FOR THOSE LOCATED IN SUCH PLACES AS WALPACK, PEQUEST, THE TYPICALLY COLDEST LOW LYING AREAS IN THE NW FRINGE OF OUR FORECAST AREA. A BIT OF HIGH THIN CIRRUS POSSIBLE TOWARD SUNRISE SATURDAY? FCST GENERALLY FROM A 5050 BLEND OF 00Z/22 NCEP MOS GUIDANCE (GFS/NAM). CONFIDENCE: ABOVE AVERAGE. && .LONG TERM /SATURDAY THROUGH THURSDAY/... THE SYNOPTIC SETUP IS COMPRISED OF A CLOSED LOW MOVING FROM NORTHERN NEW ENGLAND TO THE CANADIAN MARITIMES SATURDAY. THIS IS DUE TO ENERGY STARTING TO EJECT INTO THE CENTRAL AND SOUTHERN PLAINS, WHICH WILL ALSO BUILD A RIDGE FROM FLORIDA NORTHWESTWARD INTO THE MIDWEST SATURDAY INTO MONDAY. THE RIDGE STRENGTHENS SOME AS IT SHIFTS EASTWARD MONDAY AND TUESDAY, HOWEVER IT SHOULD THEN START TO FLATTEN SOME ON ITS NORTHERN SIDE FROM ABOUT TUESDAY ONWARD. THE MAIN FEATURE IS A FRONTAL BOUNDARY THAT SLIDES ACROSS THE NORTHEAST BUT THIS THEN LIFTS BACK NORTHWARD AS A WARM FRONT MONDAY. IT LOOKS TO TURN RATHER WARM TO EVEN HOT NEXT WEEK AS THE UPPER-LEVEL RIDGE IS IN PLACE DESPITE IT GRADUALLY SHIFTING MORE OFFSHORE WITH TIME. WE USED A MODEL BLEND FOR SATURDAY THROUGH MONDAY, THEN THE 00Z WPC GUIDANCE WITH CONTINUITY THEREAFTER. SOME TWEAKS WERE THEN MADE FOLLOWING ADDITIONAL COLLABORATION WITH OUR NEIGHBORING OFFICES. FOR SATURDAY...A CHILLY START /PATCHY FROST UP NORTH/, OTHERWISE HIGH PRESSURE STARTS TO SHIFT OFFSHORE AT NIGHT AS RIDGING BUILDS TO OUR WEST. THE AIRMASS WILL BE COOL, THEREFORE HIGHS SHOULD BE IN THE 60S TO ABOUT 70 DEGREES ACROSS THE REGION. DUE TO HIGH PRESSURE IN PLACE, LESS WIND IS EXPECTED COMPARED TO FRIDAY. FOR SUNDAY AND MONDAY...A RIDGE TO OUR WEST WILL GRADUALLY BUILD EASTWARD. SOME ENERGY SLIDING SOUTHEASTWARD ACROSS NORTHERN NEW ENGLAND WILL DROP A FRONTAL BOUNDARY INTO OUR AREA SUNDAY NIGHT. THIS BOUNDARY GENERALLY LOOKS TO BE ON THE WEAK SIDE, HOWEVER IT COULD BE ACTIVATED MONDAY AS IT LIFTS NORTHWARD AS A WARM FRONT. AS THE RIDGE BUILDS, OUR AREA IS STILL WITHIN THE NORTHWESTERLY FLOW ALOFT. THE LOW-LEVEL FLOW IS FORECAST TO BE SOUTHWESTERLY, AND THE COMBINATION OF WAA AND SOME FRONTAL LIFT AIDED BY SOME SHORT WAVE ENERGY ALONG THE FRONT SHOULD PRODUCE SOME CONVECTION ON MONDAY. IT APPEARS THAT THE BULK OF THE WAA/LIFT IS AIMED UP THE OHIO VALLEY AND ACROSS THE GREAT LAKES. WE WILL NEED TO WATCH THIS THOUGH AS SOME CONVECTION COULD SLIP INTO OUR AREA FROM THE WEST/NORTHWEST, ESPECIALLY THE NORTHERN HALF, DURING MONDAY BEFORE THE RIDGE AXIS REACHES OUR CWA. THE AMOUNT OF INSTABILITY WILL BE KEY AS WE CONTINUE TO RECOVER FROM A RATHER DRY AIRMASS THAT IS IN PLACE PRIOR TO MONDAY. OVERALL, CONVECTION MAY PRODUCE AT LEAST LOCALLY HEAVY DOWNPOURS MONDAY. A MUCH WARMER AIRMASS IS EXPECTED TO OVERSPREAD THE AREA ESPECIALLY MONDAY AS AN EXPANDING WARM SECTOR MOVES NORTH, AND SOME INCREASE IN THE DEW POINTS WILL ALSO OCCUR. FOR TUESDAY AND WEDNESDAY...WE ARE EXPECTED TO BE IN THE WARM SECTOR DURING THIS TIME FRAME AS A SHORT WAVE ALOFT AND SURFACE LOW TRACKS TO OUR NORTH, WHICH WILL FLATTEN THE RIDGE SOME. WHILE THE SURFACE COLD FRONT IS CURRENTLY FORECAST TO STAY WELL TO OUR NORTH AND WEST, SOME CONVECTION CANNOT BE RULED OUT. THIS APPEARS TO BE MAINLY FOCUSED NEAR A LEE SIDE TROUGH IN THE PRESENCE OF A WARM/HOT AND INCREASINGLY HUMID AIRMASS. GIVEN THE PRESENCE OF THE RIDGE AND THE NORTHWESTERLY FLOW ALOFT BREAKING DOWN ACROSS OUR AREA, ANY CONVECTION COULD BE SLOW MOVING WHICH WOULD RESULT IN LOCALLY HEAVY RAIN. AS OF NOW, THE WESTERN ZONES HAVE A HIGHER CHC OF CONVECTION GIVEN THE FORECAST PLACEMENT OF THE RIDGE AND ALSO A LEE SIDE TROUGH. SOME PLACES ARE FORECAST TO REACH 90 DEGREES EACH AFTERNOON. THE AFTERNOON HEAT INDICES ARE FORECAST TO BE CLOSE TO 95 DEGREES ESPECIALLY WEDNESDAY AFTERNOON FOR THE URBANIZED AREAS OF THE PHILADELPHIA METRO. IT SHOULD BE COOLER ALONG THE COAST DUE TO A SOUTHERLY FLOW. FOR THURSDAY...IT LOOKS TO BE A REPEAT OF THE PREVIOUS TWO DAYS AS WE REMAIN IN THE WARM SECTOR, MEANWHILE A COLD FRONT SLOWLY SAGS SOUTHEASTWARD ACROSS THE GREAT LAKES. SOME OF THE GUIDANCE IS FASTER WITH THIS FRONT, HOWEVER WE WENT WITH THE WPC TIMING. ONCE AGAIN A WARM TO EVEN HOT DAY IS ANTICIPATED, ALTHOUGH IT MAY BE A LITTLE COOLER AS THE RIDGE WEAKENS SOME. SINCE A SOUTHERLY FLOW IS FORECAST, IT SHOULD BE COOLER ALONG THE COAST. SOME MAINLY AFTERNOON AND EVENING CONVECTION IS POSSIBLE ESPECIALLY INLAND, PROBABLY FOCUSED ALONG A LEE SIDE TROUGH. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY...VFR CLEAR BECOMING SCT-BKN AOA 6000 FT THIS AFTN WITH THE SLIGHT CHC OF A WLY 38KT GUSTY SPRINKLE OR LIGHT SHOWER AHEAD OF A COLD FRONT. GENERALLY GRADIENT WLY GUSTS 20 KT THIS MORNING INCREASE TO 25-33 KT THIS AFTN. TONIGHT...VFR CLEAR. THIN CIRRUS POSSIBLE TOWARD SUNRISE SATURDAY. WSHIFT TO 20-25KT GUSTY NNW THIS EVENING FROM NORTH TO SOUTH, FIRST NEAR I-80 AROUND 00Z REACHING KPHL/KACY AROUND 03-05Z. CONFIDENCE: ABOVE AVERAGE. OUTLOOK... SATURDAY...VFR. NORTHWEST WINDS AROUND 10 KNOTS, BECOMING WEST- SOUTHWEST DURING THE AFTERNOON. SUNDAY...VFR. SOUTHWEST WINDS 10 TO 15 KNOTS, THEN DIMINISHING SOME AT NIGHT. MONDAY AND TUESDAY...MAINLY VFR. SOME SHOWERS AND THUNDERSTORMS ARE POSSIBLE ESPECIALLY DURING MONDAY. SOUTHWEST WINDS MAINLY AROUND 10 KNOTS.
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&& .MARINE... SAFE BOATING WEEK CONCLUDES TODAY. OUR FINAL PUBLIC INFORMATION STATEMENT FOR THIS SEASON POSTED AT 408 AM WITH THE SOCIAL MEDIA POST AROUND 8AM. I DID GO AHEAD AND ADD THE NEW USCG SAFETY APP TO MY SMART PHONE, JUST IN CASE IT COMES IN HANDY VIA MARINE RELATED TALKS/INTERVIEWS. THE FORECAST... STARTED SCA IMMEDIATELY ON DE BAY. 26 KT SHIP JOHN AND 30 KT CAPE MAY MESONET AS OF ABOUT 620 AM. SCA VCNTY 44009 EARLY TODAY WITH SEAS NOW RESPONDING. OTRW...SCA ALL OTHER WATERS WITH THE PRIMARY THREAT PERIOD OF 2P- MIDNIGHT. WLY WIND GST 25-30 KT THIS AFTN AHEAD OF A COLD FRONT THEN JUST AFT OF THE COLD FRONTAL PASSAGE WIND SHIFT TO NNW THIS EVENING. STRONGEST WIND NEAR THE SHORE WHERE ITS WARMER AND BETTER MIXING-MOMENTUM TRANSFER. WINDS DIMINISH TOWARD SUNRISE SATURDAY. OUTLOOK... SATURDAY AND SUNDAY...NORTHWEST WINDS DIMINISHING SATURDAY AND THEN BECOMING SOUTHWEST TOWARD EVENING. THE SOUTHWESTERLY FLOW CONTINUES SUNDAY AND SHOULD INCREASE SOME, HOWEVER OVERALL THE CONDITIONS SHOULD BE BELOW ADVISORY CRITERIA. MONDAY AND TUESDAY...A SOUTHWESTERLY FLOW OF 10-20 KNOTS IS ANTICIPATED WITHIN A WARM/HOT AIRMASS. THIS MAY RESULT IN THE HIGHER WINDS CLOSER TO THE COAST. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE ESPECIALLY MONDAY. SEAS AT OR BELOW 4 FEET, ALTHOUGH THESE MAY NEAR 5 FEET TUESDAY ACROSS THE NORTHERN COASTAL WATERS. && .FIRE WEATHER... WIND GUSTS OF 25 TO 35 MPH ARE EXPECTED THIS AFTERNOON AND RELATIVE HUMIDITY VALUES SHOULD FALL INTO THE 20 TO 30 PERCENT RANGE IN MUCH OF OUR REGION AT THAT TIME. HOWEVER, YESTERDAYS RAINFALL IS FORECAST TO KEEP FINE FUEL MOISTURE FROM FALLING BELOW CRITICAL LEVELS AT THOSE LOCATIONS WHERE THE GREEN-UP IS NOT COMPLETE, MOST NOTABLY THE PINE BARRENS. AS A RESULT, WE ARE NOT ANTICIPATING ANY FIRE WEATHER ISSUES FOR FRIDAY. && .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... **LITTLE DOUBT THAT A TOP 10 WARMEST MAY WILL OCCUR IN LARGE PORTIONS OF OUR FORECAST AREA** THE FIRST 21 DAYS OF MAY IN OUR FORECAST AREA WERE AVERAGING ABOUT 6 DEGREES ABOVE NORMAL. RUNNING THE NUMBERS FROM THIS MORNINGS 330AM FCST THROUGH THE 28TH AND THE 00Z/22 FTPRHA (GFS MOS) FOR THE LAST 3 DAYS BEYOND OUR WFO RESPONSIBILITY (29-31) 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 65.9 OR ABOUT 6 DEGREES ABOVE NORMAL WHICH WOULD BE 4TH-5TH WARMEST ON RECORD. 1991 WAS THE WARMEST WITH 67.2, FOLLOWED BY 2012 66.1, THEN 1944 WHEN MAY AVERAGED 66.0 AND FINALLY THE 2004 65.9 DEGREE AVG. THE NEXT WARMEST WAS 65.3 IN 1939. 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...
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PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT SATURDAY FOR ANZ450>453. SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ454- 455. SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ430-431.
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&& $$ SYNOPSIS...GORSE NEAR TERM...DRAG/ROBERTSON SHORT TERM...DRAG LONG TERM...GORSE AVIATION...DRAG/GORSE MARINE...DRAG/GORSE FIRE WEATHER... RIP CURRENTS... CLIMATE...

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