Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 271707 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 107 PM EDT SUN JUL 27 2014 .SYNOPSIS...
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A LOW PRESSURE SYSTEM WILL MOVE EASTWARD FROM THE GREAT LAKES REGION AND DRAG A COLD FRONT ACROSS THE AREA ON MONDAY. HIGH PRESSURE WILL START TO MOVE INTO THE REGION ON TUESDAY, BUILDING ACROSS THE REGION THROUGH THE WEEK.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/... NO BIG CHANGES ARE PLANNED WITH THIS UPDATE. KPBZ MORNING SOUNDING SHOWING WHY THERE IS A LULL IN ACTIVITY AT THE PRESENT MOMENT AS THERE WAS A POCKET OF COOL AIR ADVECTION OVER PA AT 925MB AND 850MB. GENERAL UA ANALYSIS SHOWING A PAIR OF 700MB TROFS, ONE JUST EAST OF THE SUSQ VALLEY AND THE OTHER IN THE CENTRAL OH VALLEY. THIS ALSO COINCIDES WITH MUCH DRIER AIR AT 500MB AND THE EXIT REGION OF THE APPROACHING 300/250MB JET. THIS IS THE REAL DEAL AS THERE IS WAA WEST OF PBZ AT 925/850MB AS WELL AS PRESENTLY THE BEST VALUES OF EFFECTIVE BULK SHEAR AND ML CAPES ALREADY EXCEEDING 1000J. LOCALLY THE WEST WINDS BEHIND THE DEPARTING SHORT WAVE HAVE DROPPED DEW POINTS BACK DOWN INTO THE MID TO UPPER 60S MOST PLACES. CONVECTIVE TEMPS THOUGH ARE IN THE LOWER 80S NORTH, BUT NEAR 90 DELMARVA. THE DELMARVA PBLM IS COMPLICATED BY DEBRIS CLOUDINESS OVERHEAD AND TO THE WEST. THUS THE WAITING GAME CONTINUES WITH THE HARDEST AND MOST LIKELY IMPACT FOR OUR CWA DURING TONIGHT. THE MESOSCALE MODELS ARE POPPING SOME DISCRETE CELLS DURING THE AFTERNOON OVER THE HIGHER TERRAIN. HAVE GREATER CONFIDENCE ABOUT THE POCONOS THAN THE BLUE RIDGE ATTM BECAUSE OF CLOUDS OVER THE LATTER. BUT THE AFTERNOON IS LONG ENOUGH THAT NEITHER CAN BE DISCOUNTED. GIVEN THE PREDICTED INCREASE IN BULK SHEAR, THESE TOO ARE CAPABLE OF BEING STRONG/SEVERE TSTMS AND WE WILL KEEP ENHANCED WORDING IN FOR THIS AFTERNOON. GIVEN HOW QUICKLY TEMPERATURES ARE RESPONDING, WE ARE GOING TO UP MAX TEMPS TO INCLUDE SOME 90S. BUT DEW POINTS HAVE DROPPED AND THIS KEEPS HEAT INDEX VALUES BELOW ANY HEAT ADVISORY THRESHOLDS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... FOR TONIGHT, THE AFOREMENTIONED CDFNT WILL CROSS THE REGION. THE HIGHEST POPS THRU THIS WHOLE EVENT COULD END UP BEING TONIGHT FIRST WITH TSTMS THEN WITH SOME SHWRS. THERE ARE STILL TIMING ISSUES WRT TO THE FRONT, BUT IT STILL WILL NOT HAVE CLEARED THE REGION BY DAYBREAK MON. THE GFS IS FASTER THAN THE ECMWF, WHICH IS NOT SURPRISING. && .LONG TERM /MONDAY THROUGH SATURDAY/... AT THE SURFACE...A COLD FRONT WILL CROSS THE REGION ON MONDAY. HIGH PRESSURE FROM THE WEST WILL GRADUALLY BUILD INTO THE REGION THROUGH THE END OF THE WEEK. IN THE MID LEVELS...A MID LEVEL TROUGH WILL DIG DOWN ACROSS THE EASTERN UNITED STATES, WITH MULTIPLE SHORTWAVES ROTATING THROUGH IT DURING THE WEEK. THE TROUGH STARTS TO RETROGRADE AND WILL DEEPEN AS IT SETTLES TO OUR WEST. BY MONDAY MORNING, A LOW PRESSURE SYSTEM WILL BE LOCATED ACROSS EASTERN NEW YORK AND WILL BE MOVING INTO NEW ENGLAND. THIS LOW WILL DRAG A COLD FRONT INTO OUR REGION DURING THE MORNING, CROSSING THROUGH THE REGION DURING THE DAY. SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE WITH FRONTAL PASSAGE AND WITH PRECIPITABLE WATER VALUES INCHING UP TOWARDS 2 INCHES, THERE WILL BE A THREAT FOR SOME HEAVY RAINFALL. SHOWERS WILL DECREASE THROUGH THE DAY AS THE FRONT PUSHES OFFSHORE, WITH ONLY SOME LINGERING SHOWERS THROUGH THE EVENING WITH PRECIPITATION ENDING BEFORE MIDNIGHT. HIGH PRESSURE WILL START TO BUILD INTO THE REGION ON TUESDAY AND EVENTUALLY WILL OVERSPREAD THE AREA BY THE END OF THE WEEK. WHILE IT APPEARS WE SHOULD REMAIN MOSTLY DRY THIS WEEK WITH THE HIGH BUILDING INTO OUR AREA, SHORTWAVES EMBEDDED IN THE MID LEVEL FLOW WILL BE ROTATING THROUGH THE BASE OF THE TROUGH AND MAY HELP TO SPARK OFF SOME SHOWERS. HOWEVER, THIS WILL BE DEPENDENT ON WHERE THE SHORTWAVES MOVES THROUGH THE REGION FROM DAY TO DAY. AS THE TROUGH RETROGRADES, IT DEEPENS AND AS A RESULT, WE SHOULD START TO HAVE AN INCREASE IN MOISTURE ACROSS OUR AREA. SHORTWAVES WILL CONTINUE TO ROTATE THROUGH THE MID LEVEL FLOW AND AGAIN MAY AID IN THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS, MAINLY TOWARD THE END OF THE WEEK AND HEADING INTO THE WEEKEND. WITH THE DEEPENING MID LEVEL TROUGH NEAR OUR AREA, OUR TEMPERATURES WILL COOL OFF A BIT AND BE BELOW NORMAL BEHIND THE COLD FRONTAL PASSAGE. AS THE TROUGH STARTS TO PUSH TO THE WEST, WE SHOULD START TO SEE A MODERATION IN THE TEMPERATURES OCCUR FOR MID TO LATE WEEK. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. 18Z TAFS HAVE A HIGH CONVECTIVE IMPACT DURING THIS EVENING INTO THE EARLY OVERNIGHT ACROSS THE TERMINALS AND AIRPORTS. THIS AFTERNOON. VFR WITH CUMULUS CLOUDS EXPANDING AND SOME CIRRUS ABOVE THEM SOUTH. NO THUNDER MENTIONED ALTHOUGH SOME ISOLATED THUNDER MIGHT FORM BEFORE THE ORGANIZED SYSTEM. LOWEST CONFIDENCE ABOUT NO THUNDER IN PA. PLEASE WATCH FOR UPDATES. WINDS WILL SLOWLY BACK FROM THE WEST TO SOUTHWEST OR EVEN SOUTH AT SPEEDS OF AROUND 10 KTS. THIS EVENING, EXPECTING A LINE OF STRONG TSTMS TO MOVE THROUGH THE AREA. HIGHEST CONFID AT KABE AND KRDG. LOWEST AT KMIV AND KACY. A EARLY TIMING HEDGE WAS MAINTAINED (MOST LIKELY TIME IS TOWARD THE MIDDLE OF THE TEMPO GROUP). MVFR TO BRIEFLY IFR (BECAUSE OF BREVITY NOT INCLUDED) CONDITIONS LIKELY ALONG WITH GUSTY WEST WINDS. OVERNIGHT PREVAILING MVFR CONDITIONS EXPECTED TO CONTINUE DURING SHOWERS. ISOLATED THUNDER POSSIBLE, BUT CONFIDENCE TOO LOW AS TO WHERE OR WHEN TO INCLUDE. WINDS WILL BE LIGHTER, GENERALLY FROM THE SOUTH. IMPROVEMENT TOWARD MORNING AS PCPN ENDS. THINKING TOO MUCH WIND FOR SGFCNT FOG TO FORM. MONDAY MORNING, VFR CONDITIONS WITH A CUMULUS BASED CIG OCCURRING. GUSTY WEST WINDS, ESPECIALLY FOR JULY, WITH SUSTAINED SPEEDS AROUND 15 KTS AND GUSTS TO AROUND 25 KTS. SOME WIDELY SCATTERED SHOWERS SHOULD START DEVELOPING TOWARD THE END OF THE CURRENT TAF FCST PERIOD. GREATEST CONFIDENCE NORTH, REASON FOR NOW LEFT OUT OF KPHL TAF. OUTLOOK... MONDAY NIGHT...VFR CONDITIONS. LEFTOVER SHOWERS EARLY...THEN CLEARING. WINDS WILL DIMINISH THROUGH THE EVENING, AROUND 5 KT OR LESS THROUGH THE OVERNIGHT. TUESDAY THROUGH THURSDAY...MAINLY VFR CONDITIONS ARE EXPECTED.
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&& .MARINE... SLY TO SWLY FLOW WILL PREVAIL OVER THE AREA WATERS AND SEAS WILL CONTINUE TO SLOWLY RISE. BY DAYBREAK MON, WE COULD BE VERY CLOSE TO SCA CONDS, ESPECIALLY OVER THE SRN WATERS, BUT CONFIDENCE IS NOT HIGH ENOUGH TO ISSUE ANY HEADLINES ATTM. OUTLOOK... MONDAY...SEAS WILL BUILD IN ADVANCE OF A COLD FRONT AND LOOK TO BUILD NEAR 5 FEET WITH WINDS GUSTING BETWEEN 20-25 KT. A SMALL CRAFT ADVISORY MAY BE NEEDED FOR MONDAY. MONDAY NIGHT...IMPROVING CONDITIONS AS BOTH SEAS AND WINDS ARE EXPECTED TO DROP AS THE COLD FRONT MOVES OFFSHORE. TUESDAY THROUGH THURSDAY...SUB-ADVISORY CONDITIONS ARE EXPECTED. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...MEOLA NEAR TERM...GIGI SHORT TERM...NIERENBERG LONG TERM...MEOLA AVIATION...GIGI/MEOLA MARINE...NIERENBERG/MEOLA

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