Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 161627 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1227 PM EDT SAT AUG 16 2014 .SYNOPSIS... WEAK HIGH PRESSURE WILL INFLUENCE THE MID ATLANTIC TODAY. A COLD FRONT WILL APPROACH FROM THE GREAT LAKES TONIGHT BEFORE MOVING THROUGH THE AREA SUNDAY. THE FRONT WILL STALL TO THE SOUTH OF THE AREA MONDAY. A WAVE OF LOW PRESSURE WILL TRACK ALONG THE FRONTAL BOUNDARY AND ACROSS THE MID-ATLANTIC REGION MONDAY NIGHT AND TUESDAY. HIGH PRESSURE RETURNS WEDNESDAY. HIGH PRESSURE WILL BECOME ESTABLISHED ACROSS THE SOUTHERN AND CENTRAL UNITED STATES LATE IN THE WEEK WHILE A SERIES OF DISTURBANCES TRACK AROUND THE NORTHERN PERIPHERY OF THE HIGH AND THROUGH OUR REGION. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WITH THE 12:30 AM UPDATE MAXIMUM TEMPERATURES WERE LOWERED SLIGHTLY AS SOME HIGH CLOUDS HAS PREVENTED MAXIMUM HEATING TODAY. DEWPOINTS HAVE ALSO BEEN LOWERED SOME ACROSS THE 1-95 CORRIDOR IN LINE WITH THE RECENT METAR OBS. THINK THE RAP IS OVERDONE WITH SHOWERS DOWN SOUTH FOR THIS AFTERNOON AND HAVE REMOVED THIS PRECIPITATION CHANCE FROM THE FORECAST. THE MAJORITY OF THE REGION WILL STAY RAIN FREE TODAY WITH THE ONLY EXCEPTION BEING EXTREME SOUTHERN DELMARVA. A WEAK MID- LEVEL IMPULSE MOVING THROUGH OUR SOUTH, ALONG AN OLD FRONTAL BOUNDARY, TOUCHED OFF A FEW SHOWERS IN SOUTHERN MARYLAND THAT WILL DRIFT OVER EXTREME SOUTHERN DELMARVA THIS MORNING. ACROSS MOST OF THE REGION SOUTHWEST WINDS WILL ALLOW FOR BETTER THERMAL ADVECTION UNDER MOSTLY SUNNY SKIES AS THERE IS PLENTY OF DRY ALOFT TO MIX DOWN. TEMPERATURES WERE A BLEND OF THE MET/MAV GUIDANCE WITH A HEAVIER WEIGHING TOWARDS THE COOLER MET TODAY. THE NAM INITIALIZED BETTER AT 850 AND 925MB COMPARED TO THE MAV, HENCE THE SLIGHT EDGE TOWARDS THE MET. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/... A SLOW MOVING COLD FRONT APPROACHES FROM THE NORTHWEST LATE TONIGHT INTO SUNDAY. CONTINUED AIRMASS MODIFICATION TONIGHT, WITH DEWPOINTS RISING TOWARDS 60F, COULD PROVIDE ENOUGH MOISTURE FOR THE APPROACHING FRONT TO TAP INTO. THE BETTER FORCING LOOKS TO REMAIN OUR NORTHWEST ZONES LATE TONIGHT BUT A FEW STRAY SHOWERS COULD DRIFT ACROSS OUR NORTHERN ZONES BY TOMORROW MORNING...WE KEEP THE CHANCE POPS GOING. OVERNIGHT LOWS WILL BE A FEW DEGREES WARMER THAN THIS MORNING WITH THE WARMER STARTING POINT AND INCREASING CLOUD COVER EXPECTED. && .LONG TERM /SUNDAY THROUGH FRIDAY/... ON SUNDAY, THE MID-ATLANTIC REGION WILL BE POSITIONED TOWARD THE BASE OF AN UPPER TROUGH THAT IS ASSOCIATED WITH A CLOSED LOW OVER EASTERN CANADA. 00Z MODEL GUIDANCE IN REASONABLY GOOD AGREEMENT WITH THE SFC COLD FRONT MOVING THRU THE ERN PA/NJ SUNDAY MORNING. MAY SEE A LINGERING SHOWER IN THE PA MTS TO START THE DAY. FARTHER EAST, REMOVED MENTION OF SHOWERS WITH THE BEST UPPER FORCING FROM THE TROUGH MOVING AWAY FROM THE AREA AND LLVL DOWNSLOPING/WLY FLOW HELPING TO SCOUR OUT MOISTURE. HOWEVER, SRN PORTION OF THE FRONT IS FORECAST TO GET HUNG UP OVER NERN MD INTO THE DELMARVA UNDER WEAKER STEERING FLOW ALOFT. MODELS GENERALLY SHOW DEWPOINTS IN THE MID 60S TO NEAR 70F JUST SOUTH OF THE FRONT. THERE IS A CHANCE FOR AFTERNOON SHOWERS AND STORMS TO DEVELOP IN THESE SOUTHERN ZONES IF THE TIMING OF FROPA OCCURS LATE ENOUGH IN THE DAY TO COINCIDE WITH PEAK DIURNAL HEATING. SKIES WILL CLEAR FROM NORTH TO SOUTH BEHIND THE FRONT DURING THE AFTERNOON. POST-FRONTAL AIRMASS OVER CENTRAL AND NORTHERN NJ AND EASTERN PA WILL BE CHARACTERIZED BY NOTICEABLY DRIER AIR WITH DEWPOINTS IN THE 50S. THE COLD FRONT WILL STALL SOUTH OF THE AREA SUNDAY NIGHT INTO MONDAY. ANY SHOWER ACTIVITY WITH THE FRONT WILL SUBSEQUENTLY SHIFT SOUTH OF THE CWA. 00Z MODEL GUIDANCE COMING INTO SLIGHTLY BETTER AGREEMENT WITH A WAVE OF LOPRES DEVELOPING OVER THE MIDWEST DURING THIS TIME. THIS LOW IS THEN EXPECTED TO TRACK EASTWARD ALONG THE STALLED BOUNDARY INTO THE MID-ATLANTIC REGION LATE MONDAY INTO TUESDAY. THE PAST FEW RUNS OF THE ECMWF APPEARS TO BE SOUTHERN OUTLIER WITH REGARDS TO THE TRACK OF THIS SYSTEM, KEEPING THE BULK OF THE PRECIP SOUTH OF THE DELAWARE BAY WHILE MAJORITY OF OTHER 00Z OPERATIONAL GUIDANCE EXHIBITS A MORE NORTHERN TRACK THAT GIVES A PERIOD OF PRECIP TO JUST ABOUT THE ENTIRE AREA. HAVE CONFINED MENTION OF THUNDER TO EXTREME SOUTHERN NJ ATTM, BUT TSTM CHANCES WILL DEPEND ON HOW FAR NORTH WARM SECTOR ADVANCES. THE LOW IS EXPECTED TO MOVE OFF THE MID-ATLANTIC COAST TUESDAY AFTERNOON, ALLOWING FOR CLEARING SKIES FROM NORTHWEST TO SOUTHEAST LATE IN THE DAY INTO TUESDAY NIGHT. DRY CONDITIONS EXPECTED WEDNESDAY WITH WEAK HIPRES OVER THE AREA. UPPER RIDGE BUILDS ACROSS THE SOUTHERN/CENTRAL CONUS TOWARD THE END OF THE WEEK. THE MID-ATLANTIC REGION IS EXPECTED TO BE SITUATED TO THE NORTHEAST OF THE RIDGE AT THE SAME TIME THAT THE UPPER TROUGH LINGERS OVER THE NORTHEAST STATES. THE BELT OF STRONGER WEST-NORTHWESTERLIES ALOFT WOULD BE FAVORED CLOSE TO THIS LATITUDE. WOULD EXPECT A SOMEWHAT ACTIVE PATTERN WITH SEVERAL SHORTWAVE DISTURBANCES TRACKING ACROSS THE AREA DURING THIS TIME. CHANCE POPS ARE FORECAST FOR MOST OF THE CWA THURSDAY AND FRIDAY. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY...VFR. LIGHT AND VARIABLE WINDS TO START BECOMING SOUTHWESTERLY 8-10 KNOTS. AFTERNOON STRATOCU DECK AROUND 4-5KFT. TONIGHT...VFR. WINDS DECREASE AND REMAIN OUT OF THE SOUTHWEST. A FEW SPOTTY SHOWERS ARE POSSIBLE NEAR RDG/ABE LATE TONIGHT. CONFIDENCE LOW ON LOCATION SO LEFT OUT THEIR MENTION IN THE TAFS. OUTLOOK... SUNDAY- SLIGHT CHANCE OF A SHRA NEAR RDG/ABE IN THE MRNG. CHANCE OF TSRA AS FAR NORTH OF AS ILG IN THE AFTN. MAINLY A VFR DAY. SUNDAY NIGHT THROUGH MONDAY- VFR AND DRY. MONDAY NIGHT THROUGH TUESDAY- SHRA MOVE INTO THE AREA. LOCAL VSBY/CIG RESTRICTIONS POSSIBLE, ESPECIALLY IN SRN TERMINALS. TUESDAY NIGHT THROUGH WEDNESDAY- VFR. && .MARINE... SUB-SCA CONDITIONS EXPECTED ACROSS OUR WATERS TODAY AND TONIGHT. WINDS WILL INCREASE THIS AFTERNOON FROM THE SOUTH BETWEEN 10-15 KNOTS AND SEAS WILL SLOWLY BUILD UPWARDS OF 3 FEET THROUGH SUNDAY MORNING. LOWERED WAVE HEIGHTS SLIGHTLY WITH THE 12:30 PM UPDATE BASED ON BUOY OBS. OUTLOOK... A COLD FRONT WILL MOVE THRU THE WATERS SUNDAY. SWLY WINDS AHEAD OF THE FRONT WILL SHIFT OUT OF THE W-NW IN WAKE OF FROPA. WINDS BELOW SCA THRESHOLD. A WAVE OF LOPRES TRACKS NEAR THE DELAWARE WATERS MONDAY NIGHT AND TUESDAY. WINDS STRENGTHEN TO 15-20 KT NORTH OF THE LOW TRACK TUESDAY AND WEDNESDAY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...KLEIN NEAR TERM...GAINES/HEAVENER SHORT TERM...HEAVENER LONG TERM...KLEIN AVIATION...HEAVENER/KLEIN MARINE...GAINES/HEAVENER/KLEIN

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