Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 121318 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 918 AM EDT FRI SEP 12 2014 .SYNOPSIS... AN AREA OF HIGH PRESSURE OVER THE GREAT LAKES WILL BUILD ACROSS THE REGION TODAY AND THEN MOVE AWAY TONIGHT. A LOW PRESSURE SYSTEM AND ITS ASSOCIATED FRONTS WILL AFFECT OUR AREA SATURDAY AND SATURDAY EVENING. HIGH PRESSURE ARRIVES FOR SUNDAY AND REMAINS ACROSS THE AREA THROUGH MONDAY. THE NEXT COLD FRONT WILL ARRIVE MONDAY NIGHT AND TUESDAY, WITH HIGH PRESSURE ONCE AGAIN BUILDING IN FOR WEDNESDAY AND THURSDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THE ESTF UPDATE IS CARRYING FEW CHANGES. CLOUDS TRAPPED UNDER THE INVERSION ARE SLOWLY ERODING NORTHWEST WHILE DEBRIS CLOUDS WITH PCPN SOUTH OF OUR CWA HAS NOT REACHED INTO DELMARVA YET. TEMP RISE WAS SLOWED A BIT NORTHWEST DUE TO CLOUDS, BUT MORNING SOUNDINGS CONTINUE TO SUPPORT PREDICTED MAX TEMPS AND LIKE YESTERDAY WE SHOULD GET THERE IN MOST PLACES. SFC COLD FRONT HAS REACHED NORTH CAROLINA THIS MORNING AFTER CLEARING THE AREA LATE LAST NIGHT. MEANWHILE, HIGH PRESSURE CENTERED OVER THE WESTERN GREAT LAKES CONTINUES TO BUILD EASTWARD TOWARD THE NORTHEASTERN SEABOARD. FORECAST SOUNDINGS FOR TODAY SHOW A VERY DRY COLUMN OVERHEAD WITH PWATS BELOW 1" NORTH OF A LINE FROM ILG-ACY. GENERALLY SUNNY SKIES SHOULD PREVAIL THRU MUCH OF THE DAY FOR PA/NJ ZONES ALTHOUGH SOME CAA STRATOCU OVER THE POCONOS MAY ADVANCE FARTHER TO THE SOUTHEAST THIS MORNING AS A SHALLOW LAYER OF MOISTURE AT THE TOP OF THE BOUNDARY LAYER REMAINS TRAPPED BELOW SUBSIDENCE INVERSION. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... AT THE SFC, BROAD AREA OF HIPRES STRETCHING FROM THE CENTRAL PLAINS TO SOUTHEASTERN CANADA WILL CONTINUE TO WEDGE DOWN TOWARD THE NORTHERN MID-ATLANTIC REGION TONIGHT. THE FLOW ALOFT WILL EVENTUALLY BACK FROM THE SOUTH IN THE LOW LEVELS AND SOUTHWEST IN THE MID AND UPPER LEVELS OVERNIGHT IN RESPONSE TO AN UPPER SHORTWAVE TROUGH THAT IS EXPECTED TO STRENGTHEN AS IT MOVES THRU THE GREAT LAKES. THE SAME FRONTAL BOUNDARY THAT PASSED THRU OUR AREA LAST NIGHT WILL BEGIN TO RETURN NORTHWARD OVERNIGHT. NWP GUIDANCE HAS BEEN PERSISTENT OVER THE PAST SEVERAL DAYS ON SHOWING WEAK CYCLOGENESIS OFF THE SOUTHEAST VA COAST. EXPECT AN INCREASE IN CLOUDS THRUOUT THE NIGHT IN THIS OVERRUNNING SETUP. HOWEVER, JUST ABOUT ALL OF CWA SHOULD REMAIN DRY WITH RAIN FAVORED SOUTH AND WEST OF THE AREA OVERNIGHT (WHERE THE BETTER ISENTROPIC LIFT AND MOISTURE FLUX CONVERGENCE RESIDES NEAR THE FRONTAL BOUNDARY). STILL CANNOT RULE OUT THE POTENTIAL FOR RAIN TO REACH THE DELMARVA AS EARLY AS DAYBREAK SATURDAY MORNING IF PRECIP SHIELD EXPANDS QUICKER/FARTHER NORTH THAN CURRENTLY FORECAST, WHICH SOMETIMES OCCURS IN OVERRUNNING EVENTS. MIN TEMPS RANGE FROM THE UPPER 40S IN THE POCONOS TO NEAR 60F IN THE CITIES AND ALONG THE COAST. && .LONG TERM /SATURDAY THROUGH THURSDAY/... SATURDAY/SATURDAY NIGHT...A POTENT UPPER TROUGH SWINGS ACROSS THE GREAT LAKES AND CAUSES LOW PRESSURE TO DEVELOP OVER THE OHIO VALLEY. TWO LOW MOVE NORTHEAST...ONE TO THE NORTH AND ANOTHER JUST TO THE SOUTH. OUT CWA SEEMS TO END UP BETWEEN THE LOWS WITH MOST OF THE 00Z MODELS SHOWING A MIN OF QPF ACROSS THE AREA. IN GENERAL...HIGH CHC OR LOW LIKELY POPS ARE IN THE FCST. LOOKS LIKE A CLOUDS AND COOL DAY FOR PRETTY MUCH THE ENTIRE AREA. HIGH WILL MOSTLY BE IN THE MID/UPPER 60D NORTH AND WEST AND LOW 70S IN MOST OTHER AREAS...A FEW MID 70S POSSIBLE OVER SRN DELAWARE. QPF...PROBABLY .20 TO .40 OVER THE AREA WITH THE MOST N/W. SUNDAY THRU MONDAY...A DRY PERIOD WITH HIGH PRESSURE EXPANDING ACROSS THE AREA. A FEW SCT SHOWERS POSSIBLE OVER THE DELMARVA LATE MONDAY...WITH ONLY SLGT CHC POPS MENTIONED. TEMPERATURES A FEW DEGREES BELOW NORMAL. MONDAY NIGHT/TUESDAY...ANOTHER H5 TROUGH MOVES ACROSS THE REGION. THE LATEST EC SHOWS LOW PRESSURE FORMING OFF THE NJ COAST AND A BAND OF MOISTURE ACROSS THE AREA MON NIGHT AND TUE. WE WENT ALONG WITH THE WPC`S 35-45 PCT POPS ACROSS THE AREA. TEMPS WILL BE NORMAL...OR A FEW DEGREES BELOW FOR THE PERIOD. TUE NIGHT THRU THURSDAY...MORE HIGH PRESSURE BUILDS IN...SO ANOTHER PERIOD OF FAIR WEATHER IS EXPECTED. TEMPERATURES WILL RUN A FEW DEGREES BELOW NORMAL. && .AVIATION /13Z FRIDAY THROUGH TUESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. COLD FRONT HAS MOVED THRU ALL AREA TERMINALS. WIND DIRECTION WILL VARY BETWEEN 320-020 DEG AND SPEEDS 5 AND 10 KT THRU THE MRNG. HOWEVER, WINDS GUSTS UP TO 20 KT ARE BRIEFLY POSSIBLE IN SOUTH OF PHL BEFORE DAYBREAK IN ASSOCIATION WITH POST-FRONTAL PRESSURE SURGE. THE ONE WRENCH IN AN ALL VFR TAF MAY BE THE STRATOCU AROUND 2-3 KFT AGL THAT IS ADVANCING SOUTHWARD ACROSS THE POCONOS. DO HAVE MVFR CIGS AT ABE/RDG FOR THE NEXT COUPLE OF HOURS. WINDS VEER SLIGHTLY THIS AFTN FROM NORTH THE TO NORTHEAST AND THEN EAST-NORTHEAST TONIGHT. VFR CONDITIONS EXPECTED. OUTLOOK... SAT/SAT NIGHT...WIDESPREAD LOWER CIGS AND VSBYS IN LIGHT RAIN AND POSSIBLY SOME FOG. SUN THRU MONDAY...MOSTLY VFR. PATCHY MORNING FOG POSSIBLE. MON NIGHT/TUE...MORE LOWER CONDITIONS POSSIBLE WITH SCT SHOWERS. && .MARINE... SCA THAT WAS IN EFFECT FOR EARLY THIS MORNING HAS BEEN CANCELLED. THE NWLY WIND SURGE BEHIND THE FRONT DID NOT QUITE MATERIALIZED AS PREVIOUSLY FCST. DESPITE WIND SPEEDS NEAR 25 KT ALOFT MEASURED AT LESS THAN 1 KFT AGL ON TPHL AND KDIX RADARS, THESE STRONGER WINDS HAVE NOT MIXED DOWN TO THE SFC. WINDS WILL GENERALLY BE 15-20 KT THROUGH TONIGHT WITH A DIRECTION OUT OF THE N-NE THIS MORNING, NE THIS AFTN E-NE TONIGHT. SEAS OF 2-4 FT ARE FORECAST OVER THE COASTAL ATLANTIC WATERS AND 1-3 FT IN THE DE BAY. OUTLOOK... SAT/SAT NIGHT...AN INCREASE IN WINDS AND SEAS AS LOW PRESSURE MOVES ACROSS THE AREA. CONDITIONS SHOULD REMAIN BELOW SCA CONDITIONS HOWEVER. SUN THRU MON...HIGH PRESSURE WITH LIGHTER WINDS AND LOWER SEAS. MON NIGHT/TUE...MOSTLY SUB-SCA WITH MORE SHOWERS EXPECTED. && .RIP CURRENTS... A MODERATE RISK OF RIP CURRENTS THROUGH TONIGHT FOR THE NEW JERSEY COAST. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...O`HARA NEAR TERM...GIGI/KLEIN SHORT TERM...KLEIN LONG TERM...O`HARA AVIATION...KLEIN/O`HARA MARINE...KLEIN/O`HARA RIP CURRENTS...

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