Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 221430 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1030 AM EDT TUE APR 22 2014 .SYNOPSIS... A COLD FRONT WILL APPROACH THE REGION FROM THE WEST TODAY AND CROSS THE AREA THIS EVENING. HIGH PRESSURE WILL THEN BUILD IN BEHIND THE FRONT FOR WEDNESDAY AND THURSDAY. THE HIGH COMBINED WITH LOW PRESSURE EAST OF NEW ENGLAND WILL RESULT IN GUSTY NORTHWEST WINDS. ANOTHER AREA OF LOW PRESSURE WILL MOVE TO THE NORTH AND BRING A WEAK FRONT THROUGH THE REGION FRIDAY NIGHT INTO EARLY SATURDAY, FOLLOWED BY MORE HIGH PRESSURE AND FAIR WEATHER FOR SUNDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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BASED ON RADAR TRENDS AND HRRR GUIDANCE, WE TRIMMED BACK POPS AND ONSET OF PRECIP FOR OUR WESTERN ZONES LATE MORNING/EARLY AFTN. WE ALSO MADE SOME ADJUSTMENTS TO POPS THROUGH THE AFTN TO EVENING HOURS TO REFLECT THE TIMING OF THE FRONT THROUGH THE CWA. OTHERWISE, PRECIP AMOUNTS LOOK TO BE ON TRACK FOR LATER TODAY AS MODEL GUIDANCE CONTINUES TO SHOW LIMITED MOISTURE ASSOCIATED WITH THE FRONTAL PASSAGE. WE ALSO KEPT THE MENTION OF THUNDER FOR THE AFTN/EVE AS GFS/NAM AND EURO GUIDANCE INDICATES SOME INSTABILITY. IN ADDITION, HOURLY TEMPS/DEWPOINTS WERE ADJUSTED SOMEWHAT TO REFLECT CURRENT OBSERVATIONS AND TRENDS, BUT AFTN MAXIMUM TEMPS LOOK ON TRACK. OTHERWISE, DEEPENING LOW PRESSURE WILL MOVE ACROSS NY AND NEW ENGLAND TODAY AND AN ATTACHED COLD FRONT WILL APPROACH FROM THE WEST. THE FRONT WILL CROSS THE WRN AREAS LATE THIS AFTERNOON. OVERALL, MAINLY HIGH CHC/LIKELY POPS ARE IN PLACE WITH THE FRONTAL PASSAGE AND SMALLER CHCS FOR THUNDER. SPC HAS ONLY A GENERAL THUNDER OUTLOOKED FOR OUR REGION...WITH LIMITED CAPE AND MODEST WIND FIELDS EXPECTED. THE FRONT WILL REACH THE DEL VALLEY AROUND 23Z OR 00Z. WINDS WILL BE MOSTLY S/SW TODAY THEN SHIFT WRLY AFTER FROPA. OVERALL QPF TODAY AND THIS EVENING WILL BE MOSTLY .10 TO .25 INCHES. TEMPERATURES TODAY WILL BE MUCH ABOVE NORMAL WITH HIGHS EXPECTED TO REACH THE LOW/MID 70S IN MANY AREAS. IT WILL REMAIN COOLER ALONG THE SHORE AREAS WITH READINGS THERE STAYING MOSTLY IN THE 60S.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/... THE COLD FRONT WILL CONTINUE TO MOVE EAST ACROSS NJ/DE THEN OFFSHORE OVERNIGHT. MUCH OF THE SHOWER AND ISOLATED TSTM ACTIVITY WILL OCCUR THIS EVENING. A COLDER GUSTY NW WIND WILL COMMENCE BEHIND THE FRONT. WIND GUSTS OF 20 TO 25 MPH ARE POSSIBLE BY LATE TONIGHT. THE TEMPERATURES WILL FALL THROUGH THE 50S REACHING THE MID/UPPER 40S BY MORNING. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... HIGH PRESSURE WILL BE BUILDING INTO THE MIDWEST AT THE START OF THE EXTENDD PD AS LOW PRES DEEPENS OVER NEW ENG AND PULLS AWAY. THE PGRAD BETWEEN THE DEVELOPING LOW AND THE BUILDING HIGH WILL KEEP GUSTY N TO NW WIND OVER THE REGION BOTH DAYS. 30 TO 35 MPH GUSTS ARE PSBL, BEFORE THE WIND SETTLES DOWN ON THU. BY THU NIGHT, AN AREA OF LOW PRES WILL BE MOVG ACRS THE GRTLKS AND ITS ASSOCD CDFNT WILL APPROACH THE REGION ON FRI AND CROSS THE AREA FRI NIGHT INTO EARLY SAT. THIS FRONT WILL BRING ANOTHER CHC OF SHWRS. THERE IS VERY GOOD MDL AGREEMENT ON THIS PART OF THE FCST. HOWEVER, THERE IS MUCH LESS MDL AGREEMENT ON WHAT HAPPENS THE REST OF SAT. THE GFS SWEEPS THE FRONT THRU AND KEEPS MOST OF THE REST OF SAT DRY, SAVE FOR A FEW SCT SHWRS. THE ECMWF, ON THE OTHER HAND BRINGS A SECOND FRONT BY DURG SAT AND WOULD KEEP THE THREAT OF SHOWERS ALL DAY AND MUCH HIGHER POPS. THE CMC SUPPORTS THE DRIER GFS SOLN, SO FOR NOW, WILL GO WITH LOW CHC POPS, BUT SAT COULD END UP WETTER THAN CURRENTLY FCST AND CONFIDENCE IS LOW. THEN HIGH PRES BEGINS TO BUILD DOWN FROM CAN FOR SUN MAKING FOR ANOTHER DRY DAY ACRS THE AREA. BY MON, THERE IS YET EVEN MORE MDL DISAGREEMENT. AN AREA OF LOW PRES TAKES SHAPE ACRS THE PLAINS. IT`S WARM FRONT EXTENDS EWD AND PRECIP IS EXPECTED ALG AND N OF THAT BOUNDARY ON MON. HOWEVER, THE GUID DIFFERS AS TO WHERE THE FRONT WILL BE AND, THEREFORE, WHERE THE PRECIP WILL BE. THE ECMWF IS FURTHER S WITH THE FRONT AND THE PRECIP THAN THE GFS AND KEEPS VIRTUALLY ALL OF OUR AREA DRY ON MON, WITH THE PSBL EXCEPTION OF THE EXTREME SRN DELMARVA. THE GFS IS MUCH FURTHER N AND KEEPS THE AREA WET. THE ULTIMATE POSN OF THE FRONT AND PRECIP WILL BE GOVERNED BY THE STRENGTH AND POSN OF THE AFOREMENTIONED HIGH OVER CANADA. IF ITS STRONGER OR FURTHER S, THEN THE FRONT WILL BE FURTHER S. IF ITS WEAKER OR FURTHER N, THEN THE FRONT WILL BE FURTHER N. GIVEN THE NORMAL UNCERTAINTY AT THIS TIME SCALE AND THE DIAMETRIC OPPOSITE GUIDANCE, WILL JUST CARRY SOME LOW POPS ATTM. AFTER WED, BEHIND THE CFP....TEMPS LOOK TO BE AOA NRML THRU THE PD. SAT`S TEMP ULTIMATELY DEPENDENT ON SUNSHINE AND WHICH MDL SOLN IS CORRECT. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. A MOSTLY VFR DAY IS EXPECTED AT THE TERMINALS. A COLD FRONT WILL APPROACH FROM THE WEST THIS AFTERNOON CAUSING CLOUDS TO INCREASE AND CIGS TO LOWER. WE HAVE CONTINUED WITH VFR CONDITIONS DURING THE SHOWERY PERIOD LATER TODAY...ISOLATED TSTMS ARE EXPECTED. LOW CONFID IN THUNDER FOR THE TAF SITES...SO THEY WERE NOT MENTIONED IN THE TAFS FOR NOW. WINDS WILL BE MOSTLY S/SW TODAY THEN SWITCH WRLY THIS EVENING BEFORE BECOMING GUSTY NW TONIGHT BEHIND THE FRONT. WINDS GUSTS BETWEEN 20 AND 25 KTS POSSIBLE LATE TONIGHT. OUTLOOK... WED THROUGH THU...VFR CONDS WITH NW WINDS IN THE 20 TO 30 KT RANGE. HIGH CONFIDENCE. FRI THROUGH SAT...MAINLY VFR BUT LOCALLY MVFR IN SCATTERED SHOWERS FRI NIGHT INTO EARLY SAT. MDT CONFIDENCE.
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&& .MARINE...
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OVERALL, SUB-SCA CONDITIONS ARE EXPECTED ON THE AREA WATERS THROUGH TODAY BEFORE WINDS AND SEAS INCREASE FOLLOWING A COLD FRONTAL PASSAGE LATER TONIGHT. LATEST OBSERVATIONS FROM BUOY 44009 SHOW SEAS BETWEEN 4 TO 5 FEET, AND THIS WILL LIKELY HOLD FOR THE OUTER WATERS THROUGH THE AFTERNOON BEFORE MORE WIDESPREAD ELEVATED SEAS DEVELOP LATE TONIGHT AND THROUGH WEDNESDAY. WINDS WILL ALSO INCREASE TONIGHT BEHIND THE COLD FRONT. A SCA FLAG WILL BE IN EFFECT FOR ALL WATERS AFTER 00Z AND CARRY INTO WED MORNING. SCT SHOWERS AND ISOLATED TSTMS ARE EXPECTED LATE THIS AFTERNOON AND EARLY EVENING. OUTLOOK... WED THROUGH THU...SCA LIKELY AND GALE FORCE GSTS PSBL ON THE OCEAN FRONT WITH GUSTS AROUND 35 KT AND PSBLY HIGHER. A GALE WATCH HAS BEEN ISSUED. WIND SUBSIDING LATER THU. FRI AND SAT...NO MARINE HEADLINES ARE ANTICIPATED AT THIS TIME, THOUGH WE COULD APPROACH SCA WIND BY SAT NIGHT.
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&& .FIRE WEATHER... SOME FIRE WEATHER DANGER MAY BE PRESENT ON WEDNESDAY AND THURSDAY. GUSTY NORTHWEST WINDS WILL BE PRESENT BOTH DAYS BUT SOMEWHAT STRONGER ON WEDNESDAY. GUSTS COULD REACH OVER 30 MPH. HOWEVER...AT THIS TIME IT LOOKS LIKE RH VALUES MAY STAY ABOVE 30 PERCENT ON WEDNESDAY. RH WILL BE LOWER ON THURSDAY WITH ADDITIONAL DRYING AFTER TUESDAYS PRECIP...AND STILL GUSTY NW WINDS. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...GALE WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY MORNING FOR ANZ450>455. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 AM EDT WEDNESDAY FOR ANZ450>455. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 AM EDT THURSDAY FOR ANZ430-431. && $$ SYNOPSIS...NIERENBERG NEAR TERM...KLINE/O`HARA SHORT TERM...O`HARA LONG TERM...NIERENBERG AVIATION...NIERENBERG/O`HARA MARINE...KLINE/NIERENBERG/O`HARA FIRE WEATHER...

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