Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 121701 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 101 PM 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 DRIER AIR HAS ERODED MOST OF THE STRATOCU UNDERNEATH THE INVERSION. SUNNIER SKIES NOW FORECAST NORTH. TEMPERATURES ARE RISING ON OR CLOSE TO SCHEDULE, SO NO BIG CHANGES IN THAT REGARD. ONE CHANGE WE DID MAKE WAS TO BRING A SEA BREEZE FRONT OR WIND SHIFT INTO THE EASTERN HALF OF OUR CWA THIS AFTERNOON. SOME DEBRIS CLOUDINESS IS PASSING OVER SOUTHERN DELMARVA NOW, BUT PRECIPITATION IS EXPECTED TO REMAIN SOUTH OF OUR CWA. && .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 /18Z FRIDAY THROUGH WEDNESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. 18Z TAFS WILL BE FORECASTING VFR CONDITIONS THIS AFTERNOON AND EVENING AND BECOME MVFR OVERNIGHT AND MORE CONFIDENTLY ON SATURDAY. THIS AFTERNOON JUST SOME CIRRUS AT THE TERMINALS AS THE LOWER STRATOCU HAS ERODED WEST. A SEA AND BAY BREEZE FRONT IS EXPECTED TO FORM AND REACH KACY ABOUT 21Z, KMIV 22Z, KILG 00Z AND THE LOCAL PHILADELPHIA TERMINALS AFTER 00Z. WINDS PRECEDING THIS BOUNDARY ARE BECOMING LIGHTER FROM THE NORTH TO NORTHEAST, A TREND THAT WILL CONTINUE. AT TERMINALS AFTER THE SEA BREEZE FRONT PASSES, EAST WINDS SHOULD AVERAGE LESS THAN 10 KNOTS. THIS EVENING A PREVAILING LIGHT EASTERLY TO NORTHEASTERLY FLOW WILL GET ESTABLISHED. THIS WILL HELP START REFORMING SOME LOWER CLOUDS. MOST OF THE EVENING/OVERNIGHT THOUGH THE PREVAILING CIGS WILL BE VFR MID AND HIGH LEVEL. TOWARD MORNING THE LIKELIHOOD OF A MVFR CIG RETURNING INCREASES. THEN ON SATURDAY MVFR CIG CONDITIONS ARE PREDICTED TO PERSIST WITH RAIN MOVING INTO THE TERMINALS DURING THE LATE MORNING AND EARLY AFTERNOON. THIS MIGHT GENERATE A LOWER MVFR CIG (MAYBE IFR?) ALONG WITH THE POSSIBILITY OF SOME MVFR VSBYS ALSO. WINDS SHOULD REMAIN GENERALLY LIGHT FROM THE EAST. OUTLOOK... SAT NIGHT...IMPROVING TO VFR CIGS. SOME LOWER CONDITIONS DUE TO FOG. SUN THRU MONDAY...MOSTLY VFR. PATCHY MORNING FOG POSSIBLE. MON NIGHT/TUE...MORE LOWER CONDITIONS POSSIBLE WITH SCT SHOWERS. && .MARINE... WE ARE HOLDING OFF ON A SCA FOR SEAS FAR SOUTH BASED ON THE RELAXATION OF UPWIND GRADIENT WINDS, THINKING THAT THEY ARE CRESTING NOW AT JUST BELOW 5 FEET. 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 TO AROUND 4 FT ARE FORECAST OVER THE COASTAL ATLANTIC WATERS AND 1 TO AROUND 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 SHORT TERM...KLEIN LONG TERM...O`HARA AVIATION...GIGI/O`HARA MARINE...KLEIN/O`HARA RIP CURRENTS...

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