Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 280806 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 406 AM EDT MON JUL 28 2014 .SYNOPSIS... AN AREA OF LOW PRESSURE WILL MOVE OUT OF PENNSYLVANIA TONIGHT AND LIFT INTO NEW ENGLAND MONDAY, PULLING A COLD FRONT ACROSS THE AREA. HIGH PRESSURE WILL BEGIN MOVING INTO THE AREA LATER TUESDAY, AND REMAIN IN CONTROL OF THE WEATHER FOR THROUGH THE END OF THE UPCOMING WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THE MAJORITY OF HEAVIER SHOWERS AND THUNDERSTORMS CONTINUES TO HEAD OFFSHORE WITH THE PASSAGE OF A STRONG MID-LEVEL IMPULSE. THERE STILL REMAINS ENOUGH INSTABILITY, MOSTLY CONFINED TO THE SHOWALTER LEVEL, FOR MORE ISOLATED TO SCATTERED SHOWERS WITH A FEW RUMBLES OF THUNDER THROUGH THE MORNING HOURS. THE SURFACE COLD FRONT IS STILL WELL BACK IN WESTERN PENNSYLVANIA AND WILL SLOWLY ADVANCE TOWARDS THE EAST THIS AFTERNOON. MID-LEVEL TROUGH AND ASSOCIATED COLD POOL SHOULD BE NEARBY DURING THE PEAK HEATING HOURS TO ALLOW FOR INSTABILITY SHOWERS, AND ISOLATED CONVECTION...ALSO POSSIBLE ALONG THE FRONTAL BOUNDARY. SHOULD REMAIN BELOW SEVERE LIMITS TODAY AS THE BEST SHEAR AND VEERING WIND PROFILES EXISTS TO OUR NORTH WITH THE PASSAGE OF THE CENTER OF THE SURFACE LOW PRESSURE. WINDS BACK TOWARDS THE WEST LATER THIS AFTERNOON AND BECOME GUSTY WITH A COOLER AND DRIER AIRMASS FILTERING IN. DAYTIME HIGHS ARE EXPECTED TO BE SEVERAL DEGREES COOLER THAN TODAY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/... PRESSURE GRADIENT WILL TAKE A WHILE TO RELAX LATER TONIGHT SO NOT EXPECTING MUCH DECOUPLING TO OCCUR...A WEAK AND SHALLOW INVERSION MAY FORM ACROSS THE OUTLYING AREAS. CONTINUED MIXING SHOULD BE ENOUGH TO KEEP TEMPERATURES FROM FALLING OFF THE TABLE TONIGHT, THOUGH WITH THE COOLER AIRMASS IN PLACE CAN GIVE THE AIR CONDITIONERS A BREAK. BLEND OF THE MET/MAV WAS USED. && .LONG TERM /TUESDAY THROUGH SUNDAY/... A MOSTLY DRY START TO THE LONG TERM FORECAST, WITH PRECIPITATION CHANCES INCREASING LATER IN THE WEEK INTO THE WEEKEND. THERE MAY BE SOME LINGERING SHOWERS MONDAY EVENING AS THE FRONT CONTINUES TO PUSH OFFSHORE AND THE MID-LEVEL TROUGH LIFTS OUT, BUT ANY PRECIPITATION IS EXPECTED TO END BY MIDNIGHT. MUCH OF THE UPCOMING WEEK IS EXPECTED TO REMAIN MOSTLY DRY AS PW VALUES DROP TO AN INCH OR LOWER FOR TUESDAY AND WEDNESDAY, BUT MAY RETURN TO 1-1.25 INCHES FOR THURSDAY AND NEAR 1.5 INCHES FOR FRIDAY. HIGH PRESSURE AT THE SURFACE WILL BUILD ACROSS THE REGION, WHILE THE BROAD MID/UPPER TROUGH REMAINS IN PLACE ACROSS MUCH OF THE EASTERN HALF OF THE COUNTRY. THERE AREA NO SIGNIFICANT SHORT WAVE/VORTICITY IMPULSES THAT ARE FORECAST TO MOVE THROUGH FOR MUCH OF THE WEEK, BUT WITH THE TROUGH IN PLACE AND DAYTIME HEATING, THERE COULD BE ENOUGH DAYTIME INSTABILITY TO CREATE ISOLATED SHOWERS OR THUNDERSHOWERS FOR THE LATTER HALF OF THE WEEK. EACH DAY THE CHANCES INCREASE SLIGHTLY AND EXPAND IN COVERAGE. HOWEVER, WE DO NOT HAVE MORE THAN A SLIGHT CHANCE PROBABILITY THROUGH FRIDAY AT THIS TIME. AS WE MOVE INTO NEXT WEEKEND, WE GET A MORE SOLID RETURN OF MOISTURE ACROSS THE AREA AS PW VALUES REBOUND O 1.25-1.5 INCHES. WE ALSO HAVE A BETTER CHANCE OF VORTICITY IMPULSES AFFECTING OUR AREA WITHIN THE SOUTHWEST FLOW ALOFT, AND WITH THE COASTAL FRONT TRYING TO PUSH BACK CLOSER TO SHOWER, WE MAY HAVE A FOCUS FOR PRECIPITATION TO FORM. THEREFORE THE PRECIPITATION CHANCES INCREASE INTO NEXT WEEKEND. TEMPERATURES THROUGH THE EXTENDED ARE FORECAST TO BE CLOSE TO OR SLIGHTLY BELOW NORMAL. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THIS MORNING...EXPECTING VFR CONDITIONS TO APPROACH MVFR EARLY THIS MORNING BEFORE MIXING OUT SHORTLY AFTER SUNRISE. MOST OF THE SHOWERS AND THUNDERSTORMS ARE WELL TO OUR EAST WITH A FEW STRAY ONES ACROSS SOUTHERN NEW JERSEY AND CENTRAL PENNSYLVANIA. CIGS ACROSS SOUTHEAST PA COULD END UP BEING IFR WITH ALL THE RAIN THAT FELL LAST EVENING, BUT FOR THE TIME BEING DID NOT HIT THEM THAT HARD. TODAY...VFR WITH GUSTY SOUTHWEST WINDS VEERING TOWARDS THE WEST THIS AFTERNOON. SCATTERED TO ISOLATED SHOWERS AND A FEW RUMBLES OF THUNDER ARE POSSIBLE...MOSTLY NORTH AND WEST OF PHL. TONIGHT...VFR. SHOULD LOSE GUSTS BY LATE THIS EVENING BUT KEEP HIGHER SUSTAINED THROUGH THE OVERNIGHT HOURS WITH TIGHTER PRESSURE GRADIENT. OUTLOOK... TUESDAY-WEDNESDAY NIGHT...MAINLY VFR THURSDAY-FRIDAY...MAINLY VFR. ISOLATED SHOWERS/THUNDERSTORMS POSSIBLE BOTH AFTERNOONS, ESPECIALLY FRIDAY. && .MARINE... TODAY...WE CONTINUE THE SMALL CRAFT FOR ALL OUR WATERS TODAY, THOUGH IT MAY BE A TAD TOUGHER TO REACH THE 5 FOOT SEAS ACROSS OUR SOUTHERN WATERS THAN PREVIOUSLY THOUGHT. SURFACE COLD FRONT NEARS FROM THE WEST LATER TODAY AND WINDS SHIFT TOWARDS THE WEST-NORTHWEST. GUSTS ARE EXPECTED TO OCCUR AHEAD AND BEHIND THE FRONT...UPWARDS OF 25 KNOTS...BETTER CHANCE NORTH. TONIGHT...EXTENDED THE SMALL CRAFT FOR OUR NORTHERN TWO ZONES THROUGH TONIGHT WHERE THE TIGHTER PRESSURE GRADIENT EXISTS AND BETTER VERTICAL TRANSPORT MAY STILL OCCUR. SEAS WILL TAKE A BIT LONGER TO COME DOWN, EVEN ONCE THE WINDS VEER TOWARDS THE WEST. OUTLOOK... TUESDAY-FRIDAY...SMALL CRAFT ADVISORY CONDITIONS POSSIBLE EARLY TUESDAY MORNING, SUBSIDING AND REMAINING BELOW ADVISORY LEVELS THROUGH THE PERIOD. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ452>455. SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR ANZ450-451. SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ430- 431. && $$ SYNOPSIS...ROBERTSON NEAR TERM...HEAVENER SHORT TERM...HEAVENER LONG TERM...ROBERTSON AVIATION...HEAVENER/ROBERTSON MARINE...HEAVENER/ROBERTSON

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