Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 312210 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 610 PM EDT THU JUL 31 2014 .SYNOPSIS... WEAK HIGH PRESSURE WILL REMAIN ACROSS THE REGION TONIGHT AND INTO EARLY FRIDAY. SEVERAL WEAK DISTURBANCES AND A COASTAL FRONT WILL AFFECT THE AREA THIS WEEKEND. HIGH PRESSURE WILL BUILD ACROSS THE AREA EARLY NEXT WEEK. ANOTHER DISTURBANCE WILL MOVE TOWARD THE AREA TOWARD THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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A COUPLE OF TRULY ISOLATED SHOWERS AND THUNDERSTORMS STILL WORKING THEIR WAY ACROSS THE NORTHWESTERN PART OF OUR CWA AND WE WILL KEEP THE LOW CHANCE INTO EARLY THIS EVENING. A COUPLE OF SEA BREEZE LOCATIONS HAVE TEMPS DROPPING SLIGHTLY FASTER THAN ANTICIPATED AND SLIGHT ADJUSTMENTS WERE MADE THERE. OTHERWISE FORECAST REMAINS ON/CLOSE TO SCHEDULE. ANY ADJUSTMENTS IF NEEDED ON THE TOWARD MORNING SHOWERS WILL BE DONE WITH THE NEXT ESTF UPDATE ONCE COSPA/HRRR HAS BETTER TEMPORAL COVERAGE. THIS EVENING SHOULD BE A DRY ONE, EXCEPT FOR THE SLIGHT POSSIBILITY OF A PASSING SHOWER OR THUNDERSTORM NORTHWEST. POPS WERE LOWERED BASED ON RADAR/SATELLITE TRENDS. ANOTHER COOL AND COMFORTABLE NIGHT IS IN STORE FOR MOST OF US, WITH THE EXCEPTION BEING DELAWARE AND SOUTH JERSEY WHERE HUMIDITY WILL BE NUDGING EVER SO SLIGHTLY HIGHER. SOME LOW CLOUDS AND BRIEF LOCALIZED FOG IS POSSIBLE TOWARDS SUNRISE AS WELL. STAYED CLOSE TO THE MAV/MET ON TEMPERATURES TONIGHT AND ADJUSTED THE EVENING TEMPERATURES SLIGHTLY BASED ON THE LATEST METAR OBS AND INCORPORATED THE LATEST LAMP/LAV GUIDANCE. CLOUDS WILL BE ON THE INCREASE AHEAD OF THE NEXT SYSTEM BY SUNRISE.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... ANOTHER SHORTWAVE TO OUR WEST WILL CAUSE A SOUTHEASTERLY FLOW TO DEVELOP OVER THE REGION AND AN OFFSHORE FRONT TO BACK AND MOVE CLOSER TO THE COAST. AS A RESULT, MOISTURE WILL BE ON THE RISE ON FRIDAY, BOTH AT THE SURFACE AND AT MID-LEVELS. IT WILL FEEL MUGGY AGAIN JUST IN TIME FOR AUGUST. ALTHOUGH THE ONSHORE FLOW WILL LESSEN ANY INSTABILITY THAT DEVELOPS, SHOWERS AND ISOLATED THUNDERSTORMS WILL STILL BE POSSIBLE IN THE AFTERNOON FRIDAY WITH THE GREATEST THREAT IN THE WESTERN PARTS OF THE REGION WHERE THE SOUTHEAST FLOW WILL HAVE A LESSER IMPACT ON INSTABILITY. CAPE VALUES ARE EXPECTED TO BE NEAR 1000 J/KG IN THE WESTERN PART OF THE REGION, AND AROUND 500-800 J/KG ELSEWHERE. THIS WILL LIMIT THE THREAT FOR STRONG THUNDERSTORMS BUT WILL STILL ENOUGH TO HAVE THUNDER IN THE GRIDS. WENT A TOUCH COOLER THAN THE MAV/MET FOR TEMPERATURES BASED ON THE LIKELIHOOD OF CLOUDS AND SPOTTY SHOWERS. NOT SOLD ON THE WETNESS OF THE NAM/SREF IN TERMS OF QPF, SO WENT RATHER LIGHT WITH THIS ELEMENT. DUE TO THE SPOTTY NATURE OF ANY SHOWERS IN THE AFTERNOON WENT FAIRLY LOW WITH CHANCE POPS AND SLOWER TIMING ON ANY RAIN WHEN COMPARED TO THE NAM/GFS MORE IN LINE WITH THE RGEM/ECMWF. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... AN UNSETTLED PERIOD EXPECTED THIS WEEKEND INTO EARLY MONDAY...BEFORE AN IMPROVING PICTURE NEXT WEEK. A FRONT/INVERTED TROUGH WILL LINGER ALONG THE EAST COAST THIS WEEKEND WHILE UPPER HEIGHTS BEGIN TO BUILD. THE UPPER HIGH ACROSS THE OCEAN WILL BEGIN TO BUILD BACK ACROSS THE AREA LATE THIS WEEKEND INTO NEXT WEEK. THIS WILL BRING AN ONSHORE FLOW WITH ABUNDANT MOISTURE THIS WEEKEND. SCT SHOWERS AND TSTMS WILL BE IN THE FCST FOR FRI NIGHT AND THRU THE WEEKEND. TEMPERATURES WILL HOLD TO MOSTLY NORMAL OR A BIT BELOW NORMAL WITH ALL THE EXTRA CLOUDINESS. IT WILL BE A RATHER HUMID PERIOD HOWEVER. BY MONDAY...THE BUILDING HIGH WILL CAUSE THE ONSHORE FLOW TO WEAKEN AND THE MEAN FLOW ALOFT WILL SWITCH TO MOVE WRLY/SWLY. THIS WILL ALLOW DRIER AIR TO ARRIVE...BUT ALSO WARMER TEMPERATURES. HIGHS TUE-THU WILL MOSTLY BE IN THE MID/UPPER 80S ACROSS THE SRN AREAS AND LOW/MID 80S NORTH. THESE TEMPERATURES ARE AT OR A BIT ABOVE NORMAL. SCT SHOWERS EARLY MONDAY...THEN A MOSTLY DRY FCST FOR NEXT WEEK. && .AVIATION /22Z THURSDAY THROUGH TUESDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. GENERAL SOUTHERLY WINDS TONIGHT BEFORE BECOMING VARIABLE. LOW CLOUDS/PATCHY FOG ARE POSSIBLE TONIGHT AND SHOWING UP ON SOME BUFKIT SOUNDINGS. KEPT TAFS MORE OPTIMISTIC ATTM AS GFS/NAM GUIDANCE IS MIXED ON THIS WITH THE NAM HITTING HARDER. CLIMATOLOGY SUGGESTS A 40% OF MVFR CONDITIONS AS WELL, GIVING SOME CONFIDENCE TO LOWERING CEILINGS/VISIBILITIES BUT KEEPING VFR. BROUGHT IN A GRADUAL OVERCAST TOMORROW FROM SOUTH TO NORTH AT ABOUT 10,000 FEET LOWERING IT AT PHL BY 15Z. SHOWERS WE`RE NOT ADDED TO THE TAFS FOR TOMORROW GIVEN THE HIGHEST CHANCE IS AFTER 18Z. OUTLOOK... FRI NIGHT THRU SUN NIGHT...LOWER CIGS EXPECTED AT TIMES WITH ON ONSHORE FLOW. SCT SHOWERS/TSTMS AT TIMES WITH LOWER VSBYS. MON THRU TUE...MOSTLY VFR WITH SCT SHOWERS.
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&& .MARINE...
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SEAS AND WINDS ARE EXPECTED TO REMAIN BELOW SCA CRITERIA ATTM. SEAS ARE LIKELY TO BE AROUND THREE FEET AND WINDS LESS THAN 10 KNOTS. OUTLOOK... FRI NIGHT THRU TUESDAY ...SUB- SCA CONDITIONS EXPECTED THROUGH THE PERIOD. SCT TSTMS WILL CREATE LOCALLY HIGHER WINDS AND SEAS.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...O`HARA/99 NEAR TERM...GAINES/GIGI/VIVOLA SHORT TERM...GAINES LONG TERM...O`HARA AVIATION...GAINES/O`HARA MARINE...GAINES/O`HARA

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