Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 031129 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 729 AM EDT SUN MAY 3 2015 .SYNOPSIS... A LARGE AREA OF HIGH PRESSURE OVER THE EASTERN UNITED STATES TODAY WILL GRADUALLY MOVE OFFSHORE ON MONDAY. A COLD FRONT IS FORECAST TO WEAKEN AS IT DROPS SOUTHWARD ACROSS THE AREA TUESDAY THROUGH EARLY WEDNESDAY. HIGH PRESSURE RETURNS LATE IN THE WEEK. THE HIGH WILL EVENTUALLY SHIFT OFF THE EAST COAST NEXT WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... HIGH PRES WILL BE OVER THE SERN CONUS TODAY. SWLY FLOW WILL INCREASE AND TEMPS WILL WARM IN RESPONSE. HIGHS ARE EXPECTED TO BE IN THE MID TO UPPER 70S, WITH SOME LOCATIONS MAKING A RUN AT 80 DEGREES. NO PRECIP IS ANTICIPATED. THERE WILL BE SOME SCT CLOUDS ON AN OTHERWISE BEAUTIFUL DAY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... THE AREA OF HIGH PRES WILL MOVE EWD AND OFF THE CST AND A GENLY CLEAR SKY IS IN STORE WITH LIGHT WIND. && .LONG TERM /MONDAY THROUGH SATURDAY/... THE CENTER OF SURFACE HIGH PRESSURE WILL MOVE OFF THE MID-ATLANTIC COAST ON MONDAY. SOUTHWESTERLY RETURN FLOW AROUND THE HIGH WILL DRAW EVEN WARMER AND MORE HUMID AIR UP THE EASTERN SEABOARD. MONDAY WILL CONTEND WITH APRIL 18TH FOR THE WARMEST DAY SO FAR THIS YEAR WITH HIGHS 80-85 DEGREES (EXCEPT COOLER ALONG THE COAST AND IN THE POCONOS). CONDITIONS ACROSS THE FORECAST AREA WILL BE DRY THROUGH MONDAY NIGHT OWING TO STRONG SUBSIDENCE PRESENT BENEATH THE H8 RIDGE. A COLD FRONT WILL MOVE SLOWLY SOUTHWARD THROUGH THE AREA TUESDAY AFTERNOON AND NIGHT. CLOUDS OVERSPREADING NORTHEAST PA AND NORTHWEST NJ WILL RESULT IN SLIGHTLY COOLER HIGHS IN THE 70S ON TUESDAY. FARTHER SOUTH IN THE WARM SECTOR, HIGHS TUESDAY HAVE THE POTENTIAL TO BE CLOSE TO MONDAY`S FROM ABOUT PHILLY SOUTHWARD IF THE FRONT AND ITS ASSOCIATED CLOUD COVER HANGS BACK TO THE NORTH. MOISTURE WILL POOL ALONG THE FRONT AS NOTED BY PWATS INCREASING TO NEAR 1.5 INCHES AND SURFACE DEWPOINTS TO NEAR 60F BY THE AFTERNOON. BUFKIT SOUNDINGS FROM THE 00Z GFS AND 21Z SREF SHOW MODEST INSTABILITY (ML CAPE AROUND 500 J/KG) WHILE THE 00Z NAM DEPICTS A CONSIDERABLY MORE UNSTABLE ENVIRONMENT (ML CAPE AOA 1000 J/KG). WENT MORE CONSERVATIVE WITH FORECAST COVERAGE OF THUNDERSTORMS DUE TO THE PRESENCE OF WEAK SHEAR AND LIMITED FORCING IN ADDITION TO THE QUESTIONABLE INSTABILITY. A GENERAL WEAKENING TREND IS EXPECTED WITH THE CONVECTION AFTER SUNSET, ALTHOUGH SHOWERS MAY LINGER INTO THE OVERNIGHT AS SLIGHTLY BETTER LIFT ASSOCIATED WITH AN UPPER SHORTWAVE TROUGH ARRIVES LATE. THE FRONT MAY EITHER CONTINUE TO SAG SOUTHWARD SLOWLY OR EVEN STALL OVER THE DELMARVA WEDNESDAY MORNING. LIFT ASSOCIATED WITH THE FRONT ITSELF SHOULD WEAKEN AS THE BOUNDARY IS EXPECTED TO BECOME INCREASINGLY DIFFUSE. CONSEQUENTIALLY, COVERAGE OF SHOWERS EXPECTED TO BE RELATIVELY LOW ON WEDNESDAY. THUNDERSTORM CHANCES CONFINED TO THE LOWER DELMARVA, WHERE THESE LOCATIONS HAVE THE BEST CHANCE OF RESIDING IN THE WARM SECTOR TO THE SOUTH OF THE BOUNDARY. THE CAA BEHIND THE FRONT IS NOT SIGNIFICANT, SO THE TREND OF ABOVE NORMAL TEMPS SHOULD CONTINUE INTO WEDNESDAY. HOWEVER, WE WILL HAVE TO WATCH FOR THE POSSIBILITY OF ONSHORE FLOW TO DEVELOP. THIS MAY PREVENT TEMPS FROM REACHING 70F IN THE COASTAL PLAIN, ESPECIALLY THE EASTERLY WIND BECOMES ENHANCED BY A SEABREEZE. EXPANSIVE HIGH PRESSURE OVER THE EASTERN SEABOARD WILL PROVIDE A MAINLY DRY PATTERN THURSDAY THROUGH SATURDAY. THE HUMIDITY IS FORECAST TO INCREASE A BIT FRIDAY AND SATURDAY AS SOUTHERLY RETURN FLOW DEVELOPS WITH THE SURFACE HIGH MOVING OFFSHORE. CANNOT RULE OUT THE POSSIBILITY OF A A SHOWER DEVELOPING DURING THE AFTERNOON HOURS FRIDAY AND SATURDAY BUT THE SUBSIDENCE INVERSION UNDERNEATH THE RIDGE SHOULD MINIMIZE THE CONVECTIVE POTENTIAL. ABOVE NORMAL TEMPS WILL PERSIST WITH HIGHS IN THE 70S TO NEAR 80F EACH DAY. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDS WILL PREVAIL THRU THE TAF PD WITH HIGH PRES TO THE SE TODAY MOVG OFFSHORE TONIGHT. THE FLOW WILL BECOME SWLY BY AFTN BUT WILL BE LESS THAN 10 KTS. ONLY SCT CLOUDS ARE ANTICIPATED. WITH LIGHT FLOW, STILL EXPECTING ANOTHER SEA BREEZE AT KACY AND KMIV. AT THESE LOCATIONS, WIND COULD REACH 10 KT OR SO. OUTLOOK... MONDAY AND MONDAY NIGHT...VFR. SWLY MAY GUST TO 20 KT LATE IN THE DAY. TUESDAY AND TUESDAY NIGHT...PREDOMINATELY VFR. SCT SHRA AND ISO TSRA DURING THE AFTERNOON AND NIGHT COULD YIELD LOCAL MVFR/IFR CONDITIONS. WEDNESDAY...SHRA MAY LINGER INTO WEDNESDAY BUT MOST OF THE TERMINALS SHOULD DRY OUT. SOME MODEL SOLUTIONS ARE INDICATING EASTERLY WINDS TO DEVELOP. WILL HAVE TO WATCH FOR LOW CLOUDS AND MVFR CIGS TO ACCOMPANY MARINE LAYER. WEDNESDAY NIGHT AND THURSDAY...VFR. && .MARINE... DOGGEDLY PERSISTENT 5 FOOT SEAS NOW HAVE MADE IT INTO ALL OF OUR MARINE ZONES. WE HAVE EXTENDED THE SCA THROUGH ALL OUR WATERS FOR THIS MORNING. SINCE WINDS ARE NOW WELL BELOW SCA THRESHOLD FOR WINDS, WE CONVERTED THE SCA OVER TO HAZARDOUS SEAS ALL OCEAN ZONES. ONCE THIS SCA COMES DOWN, NO ADDITIONAL FLAGS ARE EXPECTED DURG THE REMAINDER OF THE NR AND SHORT TERM PDS. OUTLOOK... MONDAY THROUGH THURSDAY...WINDS AND SEAS SHOULD REMAIN BELOW SCA CRITERIA. THE STRONGEST WINDS ARE EXPECTED MONDAY AND TUESDAY AS HIGH PRESSURE MOVES OFFSHORE AND A S-SW FLOW AROUND 15-20 KT ENSUES. && .FIRE WEATHER... RELATIVE HUMIDITY VALUES NEAR 30 PERCENT, ALONG WITH OCCASIONAL WIND GUSTS TO NEAR 20 MPH MAY ENHANCE THE FIRE WEATHER RISK LATE IN THE DAY ON MONDAY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 11 AM EDT THIS MORNING FOR ANZ450>455. && $$ SYNOPSIS...KLEIN NEAR TERM...NIERENBERG SHORT TERM...NIERENBERG LONG TERM...KLEIN AVIATION...KLEIN/NIERENBERG MARINE...GIGI/KLEIN/NIERENBERG FIRE WEATHER...

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