Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 160144 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 944 PM EDT FRI AUG 15 2014 .SYNOPSIS... HIGH PRESSURE OVER WEST VIRGINA TONIGHT WILL MOVE EAST OF THE REGION BY SATURDAY NIGHT. A COLD FRONTAL BOUNDARY AND ASSOCIATED TROUGH OF LOW PRESSURE WILL MOVE SOUTHEAST FROM THE EASTERN GREAT LAKES INTO OUR REGION ON SUNDAY BEFORE STALLING JUST TO OUR SOUTH ON MONDAY. BY TUESDAY A WAVE OF LOW PRESSURE WILL PUSH THIS BOUNDARY NORTHWARD AS A WARM FRONT. AFTER THE PASSAGE OF THE LOW PRESSURE SYSTEM, ANOTHER COLD FRONTAL BOUNDARY WILL MOVE THROUGH THE REGION BY WEDNESDAY. HIGH PRESSURE WILL BECOME ESTABLISHED ACROSS THE SOUTHERN AND CENTRAL UNITED STATES BY THE END OF THE WEEK WITH DISTURBANCES TRAVELING AROUND THE HIGH PRESSURE AND THROUGH OUR REGION. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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AS OF MID EVENING...CONSIDERABLE MID TO HIGH-LEVEL CLOUDINESS PERSISTS OVER NJ AND ERN PA. THESE CLOUDS ARE LIKELY ASSOCD WITH SOME WEAK SHRTWV/IMPLS ROTATING AROUND THE MAIN UPPER LOW OVER ERN CANADA. WHATEVER THE CASE...THE CLOUDS HAVE BEEN MOVING STEADILY EAST AND SHOULD CLEAR THE THE NJ COAST BY MIDNIGHT OR SHORTLY AFTER. THERE IS NO PRECIP ASSOCD WITH THESE CLOUDS...BUT THEY ARE HOLDING SFC TEMPS UP SOMEWHAT THIS EVENING. TEMPS WILL DROP RAPIDLY WHEN THE CLOUDS CLEAR...ESPECIALLY SINCE WINDS HAVE DROPPED OFF AS EXPECTED DUE TO THE WEAK SFC PRES GRADIENT. PREVIOUS DISCUSSION FOLLOWS... THE SKY IS EXPECTED TO BE MOSTLY CLEAR FOR MUCH OF THE NIGHT. A WEAK IMPULSE TRAVELING IN THE CYCLONIC FLOW MAY BRING SOME CLOUDS AND EVEN A VERY SLIGHT CHANCE OF A SHOWER TO OUR FAR SOUTHERN COUNTIES TOWARD DAYBREAK. THE WEST WIND IS ANTICIPATED TO BECOME LIGHT AND VARIABLE AFTER DARK. TEMPERATURES ARE FORECAST TO FALL INTO THE 50S AT MOST LOCATIONS. SIMILAR TO THIS MORNING, BOTH ALLENTOWN AND READING MAY APPROACH THEIR RECORD LOW TEMPERATURES. A SUMMARY OF THE RECORD LOWS FOR AUGUST 16 IS INCLUDED IN THE CLIMATE SECTION BELOW. OUR OTHER SIX PRIMARY CLIMATE SITES SHOULD REMAIN ABOVE THEIR RECORD LOW TEMPERATURES.
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... THE MID LEVEL LOW IS FORECAST TO REMAIN OVER SOUTHERN QUEBEC ON SATURDAY AS SURFACE HIGH PRESSURE FROM THE WEST BUILDS ACROSS OUR REGION. A SURFACE TROUGH IS EXPECTED TO DEVELOP TO THE LEE OF THE APPALACHIANS ON SATURDAY AFTERNOON. A MOSTLY SUNNY SKY IS EXPECTED FOR SATURDAY WITH SOME CIRRUS AND SCATTERED CUMULUS. THE WIND WILL SETTLE INTO THE SOUTHWEST AND SOUTH AS THE LEE SIDE TROUGH DEVELOPS. SPEEDS SHOULD BE MAINLY IN THE 5 TO 10 MPH RANGE. MAXIMUM TEMPERATURES ARE ANTICIPATED TO BE MAINLY IN THE LOWER AND MIDDLE 80S. READINGS ARE EXPECTED TO GET NO HIGHER THAN THE 70S IN THE ELEVATED TERRAIN UP NORTH. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... SATURDAY NIGHT THROUGH SUNDAY NIGHT: A COLD FRONTAL BOUNDARY WILL MOVE FROM THE EASTERN GREAT LAKES TOWARD OUR REGION BY LATE IN THE DAY SUNDAY DECAYING AND SLOWING AS IT DOES SO. PW VALUES LOOK RATHER LOW ONLY AROUND ONE INCH WITH LIMITED OVERALL MOISTURE RETURN AHEAD OF THE BOUNDARY, NOT ANTICIPATING A HEAVY RAIN THREAT. MODELED QPF LOOKS RATHER MEAGER AS WELL. PREFERRED THE WPC QPF IDEA OF GENERAL RAINFALL OF 1/10 INCH OR LESS COMPARED TO THE LIKELY OVERDONE 09Z SREF GIVEN THE LIMITED MOISTURE. THE 12Z NAM SUGGESTS SOME INSTABILITY (1000)J/KG CAPE AHEAD OF THE FRONT PARTICULARLY FROM PHL AND POINTS TO THE SOUTH. HOWEVER THE NAM IS AN OUTLIER IN THE LATEST SREF PLUMES. THE SREF PLUME AVERAGE IS AROUND 500 J/KG CAPE. SHEAR IS ALSO MARGINAL AT BEST. THESE FACTORS TEND TO SUPPORT ONLY LOW CHANCE POPS IN ASSOCIATION WITH THE LIFT PROVIDED BY THE FRONT AND LITTLE IN THE WAY OF A SEVERE THREAT. RAIN CHANCES MAY START AS EARLY AS 06Z SUN (NW OF PHL) WITH RECENT MODEL RUNS FEATURING FASTER MODEL TIMING. TIMING OF THE HIGHEST CHANCE POPS WAS PLACED FROM NORTH TO SOUTH ACROSS THE REGION DURING THE DAY SUNDAY. WENT CLOSER TO THE WARMER MAV GUIDANCE GIVEN THE SOUTHWEST FLOW AHEAD OF THE FRONTAL BOUNDARY FOR HIGHS AND CLOSE TO THE MAV/MET BLEND FOR LOWS. MONDAY: WHAT IS LEFT OF THE FRONTAL BOUNDARY SHOULD BE SOUTH OF THE REGION. CONTINUED WITH SLIGHT/LOW CHANCE POP TO ACCOUNT FOR THIS ACROSS THE DELMARVA OTHERWISE A MOSTLY SUNNY DAY.NOT MUCH DEVIATION WITHIN THE MODELED TWO METER TEMPERATURES OR MAV/MET GUIDANCE SETS ON TEMPERATURES FOR MONDAY AND STUCK CLOSE TO THE CONSENSUS. MONDAY NIGHT THROUGH TUESDAY NIGHT: THE 00Z/12Z MODEL SUITES FROM 8/15 AND A MAJORITY OF THE ENSEMBLES/ ECMWF ENSEMBLE MEAN SUGGEST A WAVE OF LOW PRESSURE TO TRACK EAST-NORTHEAST ALONG THE BOUNDARY WITH SOME DIFFERENCES IN TRACK AND TIMING. THE MOST LIKELY TIMEFRAME SURROUNDS MONDAY NIGHT AND TUESDAY FOR IMPACTS. THE 12Z GFS LOOKS TO SUFFER FROM FEEDBACK ISSUES WHILE THE 12Z CMC LOOKS TO STRUNG OUT. THAT LEAVES THE ECMWF AND UKMET MODELS AS MORE PREFERRED FOR THIS FORECAST. THIS LOW PRESSURE SYSTEM ALSO HAS A MODELED STRONG VORT MAX ASSOCIATED WITH IT AS WELL. PW VALUES ARE LIKELY TO RISE TO OVER 2 INCHES BY TUESDAY MORNING AIDED BY FLOW OFF THE OCEAN RESULTING IN A HEAVY RAIN THREAT. SOME RUMBLES OF THUNDER ARE POSSIBLE AS WELL BUT THE SET-UP IS UNFAVORABLE FOR SEVERE STORMS. WITH THE RECENT HEAVY RAINS ACROSS SOUTHERN NJ AND THE DELMARVA FFG GUIDANCE IS ONLY 1-3 INCHES FOR SIX HOURS BUT MUCH HIGHER 3-5 INCHES ACROSS MOST OF NJ AND PA. THERE IS POTENTIAL FOR SOME LOCATIONS TO REACH FFG GUIDANCE ACROSS THE SOUTH IF THE HEAVIEST RAINS TRACK ACROSS THOSE REGIONS PER UKMET AND ECMWF. WENT SLIGHTLY WARMER THAN MEX GUIDANCE GIVEN THE LIKELY CLOUDCOVER FOR LOWS MONDAY NIGHT. AND USED A 50/50 00Z ECMWF AND WPC GUIDANCE FOR THE HIGHS ON TUESDAY, WHICH IS A FEW DEGREES COOLER THAN CONSENSUS BUT NOT NEARLY AS COOL AS THE 12Z GFS WHICH LOOKS LIKE A MAJOR OUTLIER FOR TEMPERATURES TUESDAY. WITH THE POTENTIAL FOR CLEARING WENT A HAIR COOLER THAN MEX/ECMWF MOS TUESDAY NIGHT. WEDNESDAY THROUGH FRIDAY: A COLD FRONTAL BOUNDARY WILL BE EXITING THE REGION EARLY WEDNESDAY. HIGH PRESSURE WILL BECOME ESTABLISHED ACROSS THE SOUTHERN AND CENTRAL UNITED STATES THROUGH THIS PERIOD. OUR REGION WILL BE LOCATED CLOSE TO THE RING OF FIRE ON THE EDGE OF THE HIGH PRESSURE SYSTEM. THE MAJORITY OF MODELS BRING CHANCE POPS BACK INTO THE FORECAST FOR THURSDAY AND FRIDAY. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. AS OF MID EVENING A MID-LEVEL CLOUD DECK COVERS THE AREAS FROM AROUND PHL AND NWWD BUT THESE CLOUDS SHOULD CLEAR OFF TO THE EAST BY AROUND MIDNIGHT. SCATTERED CLOUDS ARE FORECAST FOR SATURDAY. WINDS HAVE BECOME MOSTLY LIGHT AND VARIABLE THIS EVENING AND SHOULD REMAIN SO OVERNIGHT. AS THE CENTER OF HIGH PRESSURE SHIFTS OFFSHORE ON SATURDAY...THE WIND IS EXPECTED TO SETTLE INTO THE SOUTHWEST AND SOUTH WITH SPEEDS IN THE 5 TO 10 KNOT RANGE. OUTLOOK... SATURDAY NIGHT: VFR. SUNDAY AND SUNDAY NIGHT: MAINLY VFR, ISOLATED BRIEF RESTRICTIONS TO MVFR OR IFR IN ANY THUNDERSTORMS. ` MONDAY: VFR. MONDAY NIGHT THROUGH TUESDAY NIGHT: OCCASIONAL RESTRICTIONS TO MVFR OR IFR LIKELY IN SHOWERS AND THUNDER. WEDNESDAY: IMPROVING CONDITIONS TO VFR BY MIDDAY.
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&& .MARINE...
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HIGH PRESSURE WILL CONTINUE TO BUILD ACROSS THE COASTAL WATERS OF NEW JERSEY AND DELAWARE FROM THE WEST. NO MARINE HEADLINES ARE EXPECTED FOR TONIGHT AND SATURDAY. OUTLOOK... A COLD FRONT IS FORECAST TO MOVE ACROSS THE AREA ON SUNDAY OR SUNDAY NIGHT...HOWEVER THE FRONT SHOULD BE RATHER WEAK AND IS NOT EXPECTED TO RESULT IN SCA CONDITIONS. THE FRONT IS EXPECTED TO STALL JUST SOUTH OF NJ AND LOW PRESSURE MOVING EASTWARD ALONG THE FRONT COULD CREATE MARGINAL SCA CONDITIONS ON TUE OR WED.
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&& .CLIMATE... HERE ARE THE RECORD LOWS FOR AUGUST 16. ALLENTOWN 49-1945 ATLANTIC CITY 48-1972 GEORGETOWN 48-1963 MOUNT POCONO 36-1921 PHILADELPHIA 53-1979,1964 READING 51-1994 TRENTON 53-1994,1927 WILMINGTON 52-1979 && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...GAINES NEAR TERM...AMC SHORT TERM...IOVINO LONG TERM...GAINES AVIATION...GAINES/IOVINO MARINE...GAINES/IOVINO CLIMATE...MEOLA

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