Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 012004 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 404 PM EDT WED OCT 1 2014 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO WORK IN FROM THE NORTH TONIGHT BEFORE SLIDING TO OUR EAST BY FRIDAY. A VERY POTENT COLD FRONT SWEEPS THROUGH FRIDAY NIGHT INTO SATURDAY MORNING FOLLOWED BY ANOTHER BRIEF RESPITE OF HIGH PRESSURE THROUGH MONDAY. THEN A SERIES OF IMPULSES LOOK TO AFFECT THE REGION THROUGH AT LEAST MID-WEEK. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... THE WRF-NMMB INITIALIZATION LOOKED BETTER THAN THE GFS AND THE 12Z GFS RUN BASED ON ITS OWN DP/DT. THE 12Z OP GFS LOOKS TO BE ON THE SLOW SIDE. THROUGH THE SHORT TERM THIS DOES NOT RESULT IN THAT MUCH OF A DIFFERENCE IN THE SENSIBLE WEATHER EXCEPT ALONG THE GFS`S WESTERN FRINGE WHERE WE DID NOT RETROGRADE PCPN AS MUCH. THE CLOSED LOW WILL BE SLOWLY EASING ITS WAS INTO THE NY AND NEW ENGLAND COASTAL WATERS TONIGHT. THE QUESTION BECOMES HOW FAR WEST WILL PCPN GET. HERE WE SIDE WITH A CONSENSUS APPROACH (NRN NJ). SOME OF THE GFS MASS WAA FIELDS ARE NOT IN CORROBORATION WITH ITS PREDICTED MID LEVEL QVEC CONVERGENCE, SO THINKING IT MAY BE WRAPPING TOO MUCH PCPN WEST (INCLUDING AMOUNTS). LAST THOUGHTS ALSO BASED ON MOST PLACES TRACING ON THEIR HOURLY PCPN AMOUNTS TO OUR NE PRESENTLY. POPS WERE THUS KEPT AS CHANCE FOR MEASURABLE AND WE INCLUDED THE MENTION OF DRIZZLE GIVEN CURRENT OBS IN NYC AND LONG ISLAND HAVE IT AND IT WAS PBLY DRIZZLE AT ACY THIS MRNG. MOST OF OUR CWA WE ARE EXPECTING TO BECOME MOSTLY CLOUDY (OR STAY CLOUDY) AS THE FCST SOUNDINGS ARE PRETTY MOIST BELOW 850MB. TO BE CONSISTENT, THIS WOULD PRECLUDE MUCH MENTION OF PATCHY FOG AND ALSO CONTINUING TO SIDE WITH THE HIGHER STAT GUIDANCE FOR MIN TEMPS. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... GOING WITH A QUICKER MODELING TREND TO ENDING THE PCPN CHANCES BASED ON THE FASTER 500MB LOW MOVEMENT. PCPN CHANCES IN MORNING ONLY. MODELS INDICATING CONVECTIVE TEMPERATURE BEING REACHED AND MORE LOW LEVEL MOISTURE THAN EVEN TODAY. WE ARE NOT GOING TO BE FAST TO INCREASE SUNSHINE BECAUSE OF THIS. ON THE OTHER HAND ANY CHANNELIZED PVA IS DONE BY THE MIDDLE OF THE AFTERNOON. FULL SUN MACROS SUGGESTING MAX TEMPS ABOUT 5F ABOVE STAT GUIDANCE. THAT STAT GUIDANCE DROP OFF LOOKS REASONABLE GIVEN AFTN PREDICTED CONVECTIVE TEMPS ARE AROUND 70. AN INDICATOR OF POSSIBLY FASTER CLEARING TOMORROW WOULD BE IF WINDS BACK FURTHER TOWARD THE NORTHWEST THAN PREDICTED. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... OPERATIONAL MODELS ARE IN PRETTY GOOD AGREEMENT WITH THE LARGE SCALE FEATURES THROUGH THE WEEKEND. THE POTENTIAL FOR PHASING OF A STRONG NORTHERN AND SOUTHERN STREAM SYSTEM TO OUR WEST THAT CARVES OUT A VERY LARGE AND DEEP CLOSED LOW/TROUGH ACROSS THE UPPER MID-WEST BY LATE FRIDAY NIGHT WILL BE THE MAIN DRIVER FOR A MAJORITY OF THE LONGTERM PERIOD. A FEW BREAKS IN THE ACTION ARE EXPECTED WITH WEAK RIDGING, BUT OVERALL WE WILL REMAIN UNSETTLED THROUGH MID NEXT WEEK. FRIDAY...GUIDANCE HAS BEEN RUNNING A BIT SLOWER WITH BREAKING THE MID-LEVEL RIDGING DOWN AND THEREFORE KEEPS US MOSTLY DRY DURING THE DAYTIME HOURS. EASTERLY FLOW WILL KEEP US DAMP WITH LOTS OF CLOUD COVER IN PLACE. TEMPERATURES CLIMB INTO THE LOW-70S. STRONG COLD FRONT NEARS FROM THE WEST LATE FRIDAY NIGHT WITH SHOWERS BEGINNING TO OVERSPREAD. THE LACK OF INSTABILITY, WITH ITS NOCTURNAL PASSAGE, SHOULD LIMIT THE AMOUNT OF THUNDER, IF ANY, THOUGH THERE IS AMPLE LIFT WITH THIS SYSTEM TO POSSIBLY SEE A FEW TALLER UPDRAFTS. SATURDAY...THE FRONT CONTINUES TO BARREL THROUGH THE REGION EARLY. PRETTY HEFTY HEIGHTS FALLS WITH VERY ROBUST UPPER LEVEL DYNAMICS, 500MB JET NEARLY 70KTS, AND A NEGATIVELY TILTING TROUGH AXIS ARE PRIME INGREDIENTS FOR HEAVY RAINFALL...POSSIBLY EVEN A NARROW COLD FRONTAL RAINBAND. TOO EARLY TO HAVE HIGHER CONFIDENCE ON THE NARROW RAINBAND BUT THE MODELS ARE INDICATING A SHARP WIND SHIFT WITH THE STRONG FRONTAL CONVERGENCE ZONE LIFTING, LOW EQUILIBRIUM LEVELS, AND TREMENDOUS UPPER LEVEL MOMENTUM...EVEN WITH THE LACK OF SURFACE INSTABILITY. EITHER WAY THESE SHOWERS WILL BE SOAKERS AS WE TAP INTO THE GOMEX/ATLANTIC MOISTURE STREAMING FROM THE SOUTH AND EAST. ANTECEDENT CONDITIONS ARE STILL PRETTY DRY ACROSS THE REGION SO NOT EXPECTING ANYTHING OUT OF THE ORDINARY TO OCCUR WITH THE POSSIBLE HEAVIER RAIN. POST FRONTAL WINDS LOOK TO BE STRONG AS WELL WITH A DECENT ISALLOBARIC COMPONENT AND STRONG COLD AIR ADVECTION. TEMPERATURES SHOULD BE DROPPING THROUGHOUT THE DAY SO WE COULD BE LOOKING AT A LATE MORNING HIGH. SUNDAY...COLD FRONT OFF TO THE EAST WITH TROUGHING ESTABLISHING ITSELF TO OUR WEST AND A CRISP COOL AIRMASS IN PLACE. A DRY DAY IS ON TAP WITH TEMPERATURES IN THE UPPER-50S TO LOW-60S. MONDAY - WEDNESDAY...A SERIES OF UPPER LEVEL WAVES ROTATE THROUGH THE BASE OF THE TROUGH TO OUR WEST. THIS ALLOWS FOR CHANCES OF SHOWERS EACH DAY THOUGH TIMING OF THE WAVES IS NEARLY IMPOSSIBLE AT THIS JUNCTURE. TEMPERATURES SHOULD CLIMB BACK TOWARDS NORMAL. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. 18Z TAFS CONTINUED THE IDEA OF SOME VFR CONDITIONS THIS AFTERNOON, BUT THEN PREDOMINATELY MVFR TONIGHT INTO THURSDAY MORNING. INTO EARLY THIS EVENING, MAINLY MVFR CIGS AT COASTAL AIRPORTS AND TERMINALS, BORDERLINE MVFR/VFR CIGS FOR THE I95 CORRIDOR AND HIGHER TERRAIN AIRPORTS AND TERMINALS AND PREDOMINATELY VFR CIGS AT KRDG AND KABE. WINDS SHOULD BE NORTHEAST AT 5 TO 10 KNOTS. TONIGHT PREDICTING A MVFR CIG TO REFORM AT ALL AIRPORTS AND TERMINALS, CLOSEST TO IFR LEVELS AT THE COAST. BECAUSE OF THE PREDICTED CIG, WE DID NOT FORECAST THAT MUCH FOG AND MAINLY AT THE MORE RURAL TERMINALS. WINDS SHOULD BE LIGHT FROM THE NORTH. ON THURSDAY WE ARE REVERSING THE PROCESS WITH A SLIGHTLY SLOWER IMPROVEMENT TO VFR CIGS AS MOISTURE FROM NEW ENGLAND AT THE MVFR LEVEL CONTINUES TO MOVE INTO THE REGION. WINDS SHOULD BE SLIGHTLY MORE FROM THE NORTH THAN NORTHEAST AT SPEEDS OF AROUND 10 KNOTS. OUTLOOK... FRIDAY...MOSTLY VFR. RAIN, HEAVY AT TIMES LATE, OVERSPREADS THE AREA FROM THE WEST. REDUCED VSBYS AND CIGS IN HEAVY SHOWERS. EASTERLY WINDS BACK SOUTHEAST. SATURDAY...MVFR/IFR EARLY IN HEAVY RAIN, TRENDING VFR. WINDS CONTINUE TO BACK TO THE WEST-NORTHWEST BECOMING GUSTY. SUNDAY...VFR. && .MARINE...
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SEAS AT BUOY9 HAVE RISEN TO 5 FEET, ABOUT A FOOT OVER WAVE WATCH GUIDANCE. UNFORTUNATELY BUOY65 REMAINS OTS. WAVE WATCH GUIDANCE CONTINUES TO BE QUITE ROBUST WITH THE SWELLS AND EVEN IF THIS GFS BASED RUN IS TOO SLOW, SEAS SHOULD REMAIN AT OR ABOVE SMALL CRAFT ADVISORY CRITERIA INTO THURSDAY. NOT AS CONFIDENT ABOUT THE WINDS GETTING THERE AS THE JET MAY PASS EAST OF OUR COASTAL WATERS. BECAUSE OF THE LATTER, NO SMALL CRAFT ADVISORIES WILL BE ISSUED FOR DELAWARE BAY. OUTLOOK... FRIDAY...SCA CONDITIONS WILL LIKELY PERSIST ON OUR WATERS THROUGH EARLY FRIDAY AS WE CONTINUE WITH THE EASTERLY ONSHORE FLOW. SEAS WILL CONTINUE TO RUN AROUND 5 FEET. WINDS BEGIN TO BACK TOWARDS THE SOUTH-SOUTHEAST BY LATE FRIDAY AHEAD OF THE NEXT COLD FRONT. SATURDAY...STRONG COLD FRONT MOVES THROUGH. WINDS BACK TOWARDS THE WEST-NORTHWEST LATER IN THE DAY AND WITH STRONGER COLD AIR ADVECTION OCCURRING, WE COULD SEE A RETURN TO SCA CONDITIONS. GUSTY WINDS IN THE HEAVIER RAIN SHOWERS...MOSTLY IN THE MORNING. SUNDAY...RESIDUAL SCA WIND GUSTS DROP OFF BY LATE MORNING. SEAS SHOULD ALSO DROP BELOW SCA CONDITIONS TO AROUND 3-4 FEET.
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&& .TIDES/COASTAL FLOODING... WITH PERSISTENT BREEZY NORTHERLY AND NORTH NORTHEASTERLY WINDS TONIGHT INTO TOMORROW, TIDAL DEPARTURES BY TOMORROW AFTERNOONS HIGH TIDE SHOULD RANGE FROM 0.5 TO 1 FT ABOVE ASTRONOMICAL TIDE. THIS SHOULD RESULT IN TIDES BELOW MINOR FLOODING THRESHOLDS. HOWEVER, WE WILL CONTINUE TO MONITOR THE DEPARTURES OVER THE NEXT HIGH AND LOW TIDE CYCLES. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT FRIDAY FOR ANZ450>455. && $$ SYNOPSIS...HEAVENER NEAR TERM...GIGI SHORT TERM...GIGI LONG TERM...HEAVENER AVIATION...GIGI/HEAVENER MARINE...GIGI/HEAVENER TIDES/COASTAL FLOODING...

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