Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 270758 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 358 AM EDT SAT SEP 27 2014 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH THE WEEKEND. A COLD FRONT IS EXPECTED TO MOVE SOUTH ACROSS THE AREA LATE MONDAY OR MORE LIKELY TUESDAY. THEN LOW PRESSURE ALONG THE CAROLINAS ON TUESDAY WILL MOVE SLOWLY NORTHEAST WHILE HIGH PRESSURE STRENGTHENS OVER EASTERN CANADA THROUGH AT LEAST THURSDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... HIGH PRESSURE AT THE SFC AND ALOFT WILL BE BUILDING ACROSS THE AREA TODAY. AFTER SOME MORNING FOG...CLEAR SKIES ARE EXPECTED ACROSS THE REGION. TEMPERATURES WILL BE SEVERAL DEGREES ABOVE NORMAL...WITH HIGHS IN THE MID 70S OVER THE SOUTHERN POCONOS AND UPPER 70S TO LOW 80S ELSEWHERE. READINGS ALONG THE SHORE WILL PROBABLY REMAIN IN THE UPPER 70S WITH A LIGHT ONSHORE FLOW EXPECTED. WINDS WILL BE LIGHT MOSTLY FROM THE N OR NE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/... FAIR WEATHER WILL CONTINUE TONIGHT AS THE HIGH BEGINS TO MOVE EAST. MORE CLR SKIES ARE EXPECTED TONIGHT AND AGAIN SOME FOG WILL DEVELOP AFTER MIDNIGHT. THE FOG WILL LIKELY FORM ACROSS THE SAME AREAS AS FRI NIGHT...WITH THE RIVER VALLEYS AND COOLER RURAL AREAS FAVORED. LOWS TONIGHT WILL RANGE FROM THE UPPER 40S TO LOW 50S NORTH/WEST AND IN THE PINE BARRENS...TO THE UPPER 50S AND A FEW LOW 60S OVER THE URBAN AREAS AND ALONG THE SHORE. WINDS WILL BE LIGHT OVERNIGHT. && .LONG TERM /SUNDAY THROUGH FRIDAY/... TO PREFACE: THERE ARE VERY LARGE MODEL DIFFERENCES IN THE 00Z/27 CYCLE WITH THE COMPARATIVELY QUIET AND CONSISTENT GFS/GGEM CAMP WARMER AND VASTLY DRIER THAN THE 3 SUCCESSIVE OPERATIONAL CYCLES OF THE ECMWF. THE COMMON ELEMENTS...SEVERAL DAYS OF N-NE FLOW CENTERED ON MID WEEK. 500 MB: A STRONG RIDGE OVERHEAD TO START THE PERIOD ON SUNDAY SLOWLY BREAKS DOWN AS SHORT WAVES CARVE OUT A CLOSED LOW SOUTH OF LONG ISLAND DURING MID WEEK. THIS PROBABLE DEEP CYCLONIC LOW THEN ONLY EDGES EAST TO NEAR THE 40/70 BENCHMARK BY NEXT WEEKEND. TEMPERATURES: CALENDAR DAY AVERAGES 5 TO 10 DEGREES ABOVE NORMAL SUNDAY AND MONDAY AND THEN NEAR 5 DEGREES ABOVE NORMAL TUESDAY AND MAYBE AVERAGING CLOSE TO NORMAL WEDNESDAY/THURSDAY. FORECAST BASIS: UNLESS OTHERWISE NOTED THE LONG TERM PERIOD OF THIS FORECAST IS GENERALLY BASED ON A 50 50 BLEND OF THE 00Z/27 NAM/GFS MOS FOR THE PERIOD SUNDAY-MONDAY...THE 00Z/27 GFS MOS MONDAY NIGHT-TUESDAY...THEN THEREAFTER (TUESDAY NIGHT ONWARD) THE 0543Z/27 WPC GRIDDED GUIDANCE WHICH AT TIMES IS BLENDED 50 50 WITH THE 00Z/27 MEXMOS. ALL THIS IS EVENTUALLY CHECKED AGAINST THE 00Z/27 ECMWF TO SEE IF WE`RE IN THE BALLPARK WITH ECMWF CYCLICALLY PERSISTENT 18Z 2 METER TEMPERATURES. PRECIPITATION PROBABILITY GUIDANCE IS CHECKED AGAINST THE 21Z/26 SREF 3HRLY POPS FOR .01 THROUGH 00Z FRIDAY AND THEREAFTER THE 00Z/27 GEFS 6HR POPS FOR 0.05 THE DAILIES BELOW... SUNDAY...WARM AND VERY NICE. SOME INCREASING HIGH CLOUDS LATE IN THE DAY OR AT NIGHT. PWAT UNDER 1 INCH. LIGHT SOUTH TO SOUTHWEST WIND WITH COASTAL SEA BREEZES. MONDAY...MOSTLY CLOUDY AND WARM WITH A COLD FRONT APPROACHING FROM THE NORTH. PWAT INCREASE TO 1.25". LOW CONFIDENCE CHANCE OF SHOWERS AT NIGHT. LIGHT SOUTHWEST WIND. TUESDAY-THURSDAY...AS OUR PREVIOUS FORECASTER NOTED: A LOW CONFIDENCE FORECAST REGARDING THE DETAILS...DEPENDENT ON EVOLUTION OF THE MODELED UPPER LOW AND ASSOCIATED SURFACE LOW AND EASTERLY INFLOW. THE 330 AM DETERMINISTIC FORECAST SHOULD BE VIEWED AS SOME SORT OF IDEA. THE EVENTUAL REALITY THESE 3 DAYS COULD BE VASTLY DIFFERENT. THE OPTIONS ARE FOR A NOR`EASTER WITH WINDSWEPT CHILLY RAINS LATE TUESDAY INTO THURSDAY...ESPECIALLY NORTHERN AND COASTAL NJ TO JUST VARIABLE CLOUDINESS AND SEASONABLY MILD TEMPS. THIS FORECAST RAISED WPC GUIDANCE POPS WED NIGHT/THU. ITS A CONSERVATIVE FORECAST FOR POPS... CALLING IT CHANCY. 00Z/27 ECMWF OPERATIONAL GUIDANCE HAS 5.7 INCHES OF RAIN NEAR BELMAR NJ ENDING 00Z/FRIDAY WHILE THE GFS HAS .05! THE GEFS IS NOT YET SIDING WITH THE ECMWF SO THE ECMWF SOLUTION STILL IS AN OUTLIER AT THIS TIME! NEXT FRIDAY... SHOULD BE DRY AS THE UPPER LOW SHIFTS EAST AND A STRONG MIDWEST TROUGH PERMITS WEAK WARM RIDGING HERE. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. A FAIR WEATHER FORECAST FOR MUCH OF THE TAF PERIOD. THE ONLY EXCEPTION WILL BE SOME FOGGY AREAS THIS MORNING. WE HAVE KEPT IN A MENTION OF FOG AT KMIV..KACY AND KRDG. WE MAY HAVE TO CONSIDER SOME AT KABE ALSO...AMDS ARE POSSIBLE. OTHER THAN THAT...SKC AND GENTLE N TO NE WINDS EXPECTED TODAY. SKC TONIGHT WITH LIGHT AND VARIABLE WINDS. MORE FOG POSSIBLE OVERNIGHT SAT INTO SUN...WE WILL PROBABLY MENTION IT IN THE 12Z TAFS...PROBABLY FOR THE SAME AREAS AS TODAY. OUTLOOK... SUN...VFR CLEAR THEN SCT-BKN CIRRUS AOA 20000 FT DURING THE AFTN/NIGHT. LIGHT SOUTHWEST WIND. HIGH CONFIDENCE. MON...VFR CIGS. POSSIBLE MVFR VSBY IN SHOWERS AT NIGHT. LIGHT SOUTHWEST WIND BECOME E-NE AT NIGHT. TUE-WED...UNCERTAINTY ON CONDITIONS WITH A VERY LOW CONFIDENCE FORECAST ON DETAILS. FOR NOW...WE`VE FAVORED THE OUTLIER ECMWF. CIGS VARIABLE TO MVFR OR IFR CONDS IN PERIODS OF SHOWERY RAINS, WITH GUSTY N-NE WINDS, ESPECIALLY FOR COASTAL NJ. && .MARINE... THE SEAS ARE BEGINNING TO TREND DOWN A BIT AND WITH THE LEVELS NOW BELOW 5 FT...WE WILL CANCEL THE SCA FLAG THAT WAS IN EFFECT. HIGH PRESSURE WILL BUILD OVER THE WATERS TODAY AND REMAIN THRU TONIGHT. WINDS WILL BE LIGHT...MOSTLY FROM THE N OR NE TODAY AND TURNING MORE E TONIGHT. SEAS...ON THE OCEAN WILL BE AROUND 4 FT EARLY THEN MOSTLY AROUND 3 FT LATER TODAY AND TONIGHT. SEAS ON DEL BAY 1-2FT AT MOST. OUTLOOK... SUN-MON NIGHT...NO MARINE HEADLINES WITH LIGHT WINDS AND A GOOD TIME TO BE ON THE WATER BEFORE A LENGTHY SCA CONDITION DEVELOPS MIDWEEK . TIMING THE ONSET OF THE NEXT SMALL CRAFT ADVISORY IS STILL UNCERTAIN. FOR NOW WE FAVORED TUESDAY. THIS COULD STILL BE DELAYED TILL TUESDAY NIGHT. TUE-WED...SCA WINDS AND SEAS LIKELY. A BACKDOOR COLD FRONT SETTLES SSW THROUGH THE MID ATLANTIC STATES TUESDAY WITH INCREASING WIND AND SEAS BEHIND IT. WINDS AND SEAS CONTINUE BUILDING WEDNESDAY AS STRONG HIGH PRESSURE DEVELOPS OVER EASTERN CANADA AND LOW PRESSURE TRIES TO BUCK UP INTO THE HIGH...TIGHTENING THE NORTHEAST GRADIENT OVER OUR AREA. THERE IS A SMALL CHANCE NORTHEAST WINDS MAY BECOME STRONG ENOUGH TO REACH GALE FORCE WEDNESDAY. SOME OF OUR GUIDANCE SUGGESTS THAT ONCE SCA 5 FOOT SEAS BEGIN ON THE ATLANTIC WATERS TUESDAY OR TUESDAY NIGHT...THESE COULD LINGER FOR AT LEAST 3-4 MORE DAYS. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...DRAG 358 NEAR TERM...O`HARA 358 SHORT TERM...O`HARA 358 LONG TERM...DRAG 358 AVIATION...DRAG/O`HARA 358 MARINE...DRAG/O`HARA 358

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