Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 271517 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1117 AM EDT SUN JUL 27 2014 .SYNOPSIS... A WARM FRONT WILL MOVE NORTHWARD THROUGH OUR AREA TODAY. 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. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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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.
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&& .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 /15Z SUNDAY THROUGH THURSDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. A LOW CONFIDENCE AND COMPLICATED FCST DAY, BUT SHWRS AND TSTMS ARE EXPECTED TO IMPACT THE TERMINAL SITES LATER TODAY. LATEST RADAR ALREADY HAS SOME SCT SHWRS AROUND AS REMNANTS OF A SYS FROM THE MIDWEST WEAKEN AND GENLY MOVE BY TO OUR SW. THEN, A COMPLEX LOW PRES SYS IN SERN CANADA AND ITS ASSOCD CDFNT WILL APPROACH AND MOVE THRU TONIGHT INTO MON. THIS FRONT WILL TRIGGER SHWRS AND TSRA. ANY OF THE OR TSRA THIS MRNG OR LATER COULD BRING REDUCED CIGS/VSBYS. THE GUID SEEMS TO HAVE PUSHED BACK THE ONSET TIME WITH THE ACTIVITY LATER THIS AFTN/EVE, SO HAVE TAKEN THAT APPROACH IN THE TAFS, SO HAVE TRENDED IN THAT DIRECTION AND STILL COULD BE TOO FAST...OR NOT. ONCE THE CONVECTION MOVES THROUGH, THERE WILL LIKELY BE SOME LINGERING SHOWERS INTO THE NIGHT UNTIL SOME IMPROVEMENT CLOSER TO DAYBREAK OR BEYOND. A GENL S WIND IS EXPECTED ERLY. IT WILL BECOME MORE SWLY AND INCREASE TO THE 10 TO 15 KT RANGE DURG THE DAY. IT WILL DECREASE AND BECOME LIGHT (OUTSIDE OF ANY TSRA) OVERNIGHT AND GRADUALLY BECOME MORE WLY BY DAYBREAK AS THE FRONT MOVES THRU. OUTLOOK... MONDAY...A COLD FRONT WILL CROSS THE REGION WITH MVFR/IFR CONDITIONS POSSIBLE WITHIN SHOWERS AND THUNDERSTORMS. WEST TO SOUTHWEST WINDS 10 TO 15 KT WITH GUSTS 20 TO 25 KT. MONDAY NIGHT...VFR CONDITIONS ARE EXPECTED TO RETURN DURING MONDAY NIGHT AS THE FRONT PUSHES OFFSHORE. 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. && .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...NIERENBERG/MEOLA MARINE...NIERENBERG/MEOLA

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