Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 270112 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 912 PM EDT WED AUG 26 2015 .SYNOPSIS... HIGH PRESSURE ACROSS THE UPPER GREAT LAKES REGION WILL SETTLE ACROSS THE DELAWARE VALLEY BY FRIDAY AND THEN MOVE OFFSHORE THIS WEEKEND. A LOW PRESSURE SYSTEM AND FRONT WILL AFFECT THE WEATHER SUNDAY AND INTO EARLY MONDAY. MORE HIGH PRESSURE BUILDS ACROSS THE AREA NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... THE SHOWERS/SPRINKLES TO OUR WEST CONTINUE TO DIMINISH AS THE LOW-MID LEVEL LASPE RATES WEAKEN WITH THE LOSS OF DAYTIME INSTABILITY. LATEST GUIDANCE CONTINUE TO INDICATE THE SHOWERS WEAKEN AS THEY APPROACH THE AREA, SO WE`LL CONTINUE WITH A DRY FORECAST. THE CLOUDS ACROSS THE WEST HAVE BEEN RETREATING EARLY IN THE EVENING. BUT AS THE MID-LEVEL TROUGH CONTINUES TO SLOWLY SLIDE EASTWARD, THE CLOUDS MAY FILL BACK IN SOME, SO WE`LL KEEP A PARTLY CLOUD FORECAST OUT WEST. SOME MID-LEVEL CLOUDINESS HAS SPILLED ACROSS THE SOUTHEASTERN AREAS, SO WE BUMPED CLOUDS UP HERE A LITTLE. MADE NO MAJOR CHANGES TO TEMPERATURES EXCEPT MINOR HOURLY ADJUSTEMENTS. BOUNDARY LAYER WINDS ARE PREDICTED TO BE LIGHT ENOUGH FOR DECOUPLING, ESPECIALLY IN MORE SHELTERED AREAS. GIVEN THE AFTERNOON DEW POINTS, WE WENT WITH THE STAT GUIDANCE TREND OF LOWERING MINIMUM TEMPERATURES A BIT IN RURAL/OUTLYING AREAS. HIGHEST CONFIDENCE IS IN THE SOUTHERN PART OF OUR CWA. CLOUDS MAY MAKE OUR MINS NORTH TOO LOW. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... WITH THE LAST OF THE SHORT WAVES MOVING OFFSHORE BY EARLY AFTERNOON THURSDAY, THE TROF FLATTENING AND A HIGH PRESSURE SYSTEM BUILDING INTO THE EASTERN GREAT LAKES, EVEN MORE OF A CHAMBER OF COMMERCE LATE AUGUST DAY IS PREDICTED FOR OUR CWA. THE MODELS DO PASS THE 250MB JET OVER DELMARVA. THEY ARE NOT SHOWING ANY JET LAYER MOISTURE AT THIS TIME. CUMULUS COVERAGE OVERALL SHOULD BE LESS THAN TODAY. THE THERMAL TROF PASSES THROUGH AND THE PREDICTED THERMALS SUGGEST ABOUT A 1F DROP OFF IN MAX TEMPS FROM TODAY. USING PREDICTED 925MB TEMPS, WE WILL FOLLOW A GFS AND NAM MOS COMPROMISE. A BRIEF NORTHWEST SURGE BEHIND THE COLD FRONT SHOULD BECOME LIGHTER AGAIN. ALONG AND NEAR THE COAST AND BAYS, SOME SEA BREEZE INDUCED WINDS COULD DEVELOP. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... 5-WAVE MODEL GUIDANCE SHOWS A BUILDING SOUTHEAST RIDGE THROUGH A MAJORITY OF THE LONGTERM PERIOD WITH MODERATING TEMPERATURES AND HUMIDITY. FRIDAY - SATURDAY...EXPECTING A DRY FORECAST THESE DAYS WITH A WEAK FRONT NEARING FROM THE NORTHWEST. SOME GUIDANCE IS HINTING AT SHOWER ACTIVITY ACROSS THE NORTHERN SATURDAY AFTERNOON WITH A BIT OF A WEAKNESS IN THE PATTERN ALOFT BUT THINKING THAT CONVECTIVE TEMPERATURES SHOULD BE OUT OF REACH AND THE BETTER FORCING IS STILL FARTHER TO OUR NORTH AND WEST...WE STAY DRY. BOTH DAYS WE EXPECT TEMPERATURES IN THE MID-80S WITH DEWPOINTS CLOSE TO 60F. SUNDAY - MONDAY...THE AFOREMENTIONED COLD FRONT GETS CLOSER BUT WITH IT DOESN`T REALLY PACK A PUNCH BUT WE CONTINUE THE SLIGHT CHANCE WITH SOMEWHAT BETTER INSTABILITY. HIGH PRESSURE SLIDES OFF THE COAST AND ALLOWS FOR BETTER AIRMASS MODIFICATION SO WE WILL SEE AN INCREASE IN HUMIDITY AND INSTABILITY. HIGHS BOTH DAYS APPROACH, IF NOT EXCEED, 90F. TUESDAY - WEDNESDAY...NO APPRECIABLE RAIN EXPECTED EITHER DAY WITH SOUTHEAST RIDGE AXIS OVERHEAD. CONTINUED HEAT AND HUMIDITY INCREASE IS EXPECTED BUT IT DOES APPEAR THAT THE CORE OF THE WARMEST 925MB TEMPERATURES STAYS TO THE SOUTH AND WEST OF THE REGION. NONE-THE- LESS 90F IS NOT OUT OF THE QUESTION EACH AFTERNOON. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TONIGHT...VFR. WINDS WILL BE LIGHT FROM THE NORTHWEST AND MORE SHELTERED AIRPORTS/TERMINALS MAY GO CALM FOR A WHILE. NO VSBY RESTRICTIONS AT THE TERMINALS. LATE TONIGHT ANOTHER UPPER AIR DISTURBANCE MIGHT BRING SOME MID LEVEL CLOUDS ACROSS THE AREA AGAIN. HIGHEST CONFIDENCE NORTHWEST AIRPORTS AND TERMINALS. THURSDAY...A NEAR CARBON COPY OF TODAY. SOME HIGH BASED CUMULUS CLOUDS SHOULD DEVELOP AGAIN, PROBABLY LESS OVERALL COVERAGE THAN TODAY. NORTHWEST WINDS SHOULD AVERAGE 5 TO 10 KNOTS. A SEA BREEZE FRONT DURING THE AFTERNOON MIGHT MAKE MORE OF AN INLAND INTRUSION. OUTLOOK... THURSDAY NIGHT THRU SATURDAY NIGHT...MOSTLY VFR. PATCHY FOG PSBL DURING THE PREDAWN HOURS. SUNDAY - MONDAY...MOSTLY VFR. SHOWERS POSSIBLE WITH LOWER CONDITIONS. && .MARINE... SUB SMALL CRAFT ADVISORY CONDITIONS WILL CONTINUE TONIGHT AND THURSDAY. A PREVAILING WEST TO NORTHWEST FLOW IS ESPECTED AGAIN TONIGHT. AS THE OVERALL PRESSURE GRADIENT WEAKENS AGAIN DURING THE DAY ON THURSDAY, A MORE VARIABLE SEA BREEZE INDUCED WIND FLOW SHOULD DEVELOP AGAIN ON THE OCEAN WATERS. WE ARE NOT AS CERTAIN ABOUT AN UP (SOUTHEASTERLY WINDS) THE DELAWARE BAY FLOW OCCURRING. SUSTAINED WIND SPEEDS THURSDAY SHOULD REMAIN AT 15 KNOTS OR LESS. OUTLOOK... SUB-SCA CONDITIONS THRU THE PERIOD. SEAS WILL BUILD TO AROUND 4 FT ON THE OCEAN SAT NIGHT INTO SUNDAY. WIDELY SCT SHOWERS/TSTMS POSSIBLE SUN. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...O`HARA NEAR TERM...GIGI/ROBERTSON SHORT TERM...GIGI LONG TERM...HEAVENER AVIATION...GIGI/HEAVENER MARINE...GIGI/HEAVENER/O`HARA

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