Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 250659 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 259 AM EDT SAT APR 25 2015 .SYNOPSIS...
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WEAK HIGH PRESSURE COVERS OUR AREA EARLY TODAY. LOW PRESSURE OVER THE LOWER OHIO VALLEY WILL PASS OFF THE NORTH CAROLINA COAST SUNDAY. THAT LOW BECOMES PART OF LARGE LOW PRESSURE CIRCULATION OVER THE NORTHWEST ATLANTIC EARLY NEXT WEEK. A LOW PRESSURE SYSTEM OVER THE NORTHERN GULF OF MEXICO TUESDAY NIGHT EMERGES OFF THE SOUTHEASTERN SEABOARD LATE WEDNESDAY AND THURSDAY AND HEADS NORTHEAST.
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&& .NEAR TERM /THROUGH TODAY/...
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330 AM PACKAGE: NOT MUCH CHANGE IN THE FROST/FREEZE HAZARD AS RADIATIONAL COOLING VARIES BASED ON THE SFC WIND STIRRING BUT OVERALL...THE ADVY/WARNING IS REASONABLE AND VERIFYING. TODAY...VARIABLE HIGH CLOUD COVER. THE THICKER SKYCOVER FROM FAR SE PA AND SNJ SOUTHWARD. SPRINKLES MAY DEVELOP TOWARD 6 PM OVER TALBOT/CAROLINE AND SOUTHERN SUSSEX COUNTIES ON THE SW EDGE OF OUR FCST AREA. FORECAST TEMPERATURES TODAY WERE A 1/3RD BLEND OF THE 00Z/25 GFS/NAM MOS AND 00Z/25 ECMWF 2M TEMPS. THE ECMWF IS QUITE COOL UNDER THE CLOUDS OVER THE DELMARVA AND HAVE MODIFIED THE NCEP MOS DOWNWARD THERE. WARMEST TEMPS IN OUR FCST AREA TODAY SHOULD BE IN NORTHERN NJ WHERE THERE SHOULD BE MORE SUNSHINE. A NICE DAY WITH MUCH LESS WIND THAN THE PREVIOUS WED-THU-FRIDAY AFTERNOONS. DAYTIMES TEMPS WILL BE WARMING A BIT EXCEPT THE DELMARVA WHERE IT WILL BE CHILLY TODAY AND MAXIMUM TEMPS ALMOST 15 DEGREES BELOW NORMAL WHILE MAXIMUM TEMPERATURES AROUND ALLENTOWN AND MOUNT POCONO NEWD THROUGH NNJ SHOULD ONLY BE 8 TO 10 DEGREES BELOW NORMAL. A WEAK WIND SHIFT BOUNDARY WILL BE FORMING JUST TO OUR NORTH LATE IN THE DAY WITH WESTERLY WINDS GUSTING TO 15 MPH DURING THE AFTERNOON IN PA AND NNJ BUT SEA BREEZES SHOULD DEVELOP COASTAL NJ AND COASTAL DE. WINDS ON THE DELMARVA WILL BE LIGHT WHERE LESS MIXING IS EXPECTED DUE TO HEAVIER SKYCOVER.
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&& .SHORT TERM /TONIGHT/...
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TONIGHT...THICK HIGH CLOUD ALONG AND SOUTH OF I-78, WITH THE NORTHERN PORTION OF THE FORECAST RAIN SHIELD A BLEND OF HPC QPF, 50 50 00Z/25 NAM/GFS MOS AND MULTI MODEL .10 IN 6 HRS. THAT MEANS MAINLY THE SOUTHERNMOST 40 MILES OF OUR CWA, TALBOT COUNTY, QUEEN ANNES AND CAROLINE COUNTIES IN MD AND SUSSEX COUNTY DE, POSSIBLY KENT COUNTY DE AND POSSIBLY THE SRN TIP OF NJ. THIS CLOUD COVER TODAY AND CLOUD COVER/RAIN TONIGHT IS ASSOCIATED WITH THE LOW REDEVELOPING NEAR THE NC COAST. A WIND SHIFT FROM LIGHT WEST TO NORTH-NORTHEAST PROGRESSES FROM NORTH TO SOUTH THROUGH OUR CWA DURING THE NIGHT. PATCHY FROST IS IN THE FCST N OF I-78 TONIGHT. NO NEW FROST ADVY ATTM DUE TO THE UNCERTAINTY OF THE NORTHERN EDGE OF THICK CLOUD COVER. IT ALREADY FROZE UP THERE THIS MORNING SO EARLY SUSCEPTIBLE BLOOMS WERE PROBABLY DAMAGED.
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&& .LONG TERM /SUNDAY THROUGH FRIDAY/... THE LOW PRESSURE WILL THEN EXIT EAST AND OUT TO SEA THROUGH THE COURSE OF SUNDAY, BUT THERE COULD BE SOME LEFTOVER PRECIP THAT LINGERS OVER THE DELMARVA INTO SUNDAY MORNING, AND WE GRADUALLY DIMINISH POPS TO CHANCE AND THEN LOWER THROUGH THIS PERIOD. ELSEWHERE THROUGH THE FORECAST AREA, A DRY SUNDAY IS ANTICIPATED WITH SOME CLOUDS AND GENERALLY LIGHT NORTHERLY WINDS. MONDAY COULD PRESENT A FEW SHOWERS FOR OUR AREA AS AN UPPER DISTURBANCE/UPPER LOW LINGERS AROUND THE NORTHEAST STATES OR JUST TO THEIR EAST. MODEL FORECAST SOUNDINGS PREDICT CONVECTIVE TEMPERATURES TO BE REACHED MONDAY, SO THERE WILL BE INCREASING CLOUDS THROUGH THE DAY ALONG WITH SOME ISOLATED/SCATTERED SHOWERS EXPECTED AS COOLER AIR ALOFT ASSOCIATED WITH THE UPPER LOW LINGERS NEARBY. THE UPPER LOW PULLS AWAY OUT TO SEA INTO TUESDAY, AND WEAK HIGH PRESSURE FROM THE WEST GRADUALLY BUILDS ACROSS OUR REGION, LASTING THROUGH THE DAYTIME WEDNESDAY. WE HAVE KEPT A DRY FORECAST THROUGH THIS PERIOD, WITH RATHER LIGHT NORTHERLY WINDS AND NEAR AVERAGE END OF APRIL TEMPERATURES. THE TRICKY AND HIGHLY UNCERTAIN PART OF THE FORECAST THEN INVOLVES THE DEVELOPMENT AND TRACK OF A POTENTIALLY STRONG COASTAL SYSTEM THAT MAY BEGIN TO AFFECT OUR REGION WEDNESDAY NIGHT AND LASTING THROUGH THURSDAY TO THURSDAY NIGHT. THERE CONTINUES TO BE A WIDE RANGE OF SOLUTIONS FROM THE OPERATIONAL MODELS TO VARIOUS ENSEMBLE DATA REGARDING THE TRACK, EVOLUTION, AND INTENSIFICATION OF LOW PRESSURE, MOST LIKELY FROM AROUND THE NORTHERN GULF OF MEXICO REGION WEDNESDAY BEFORE ITS POTENTIAL EMERGENCE OFF THE EAST COAST THURSDAY. WITH THE GREATER UNCERTAINTY THROUGH THIS PERIOD, WE LEANED MORE TOWARD WPC GUIDANCE FOR MOST ELEMENTS, INCLUDING TEMPERATURES, WINDS, AND POPS, WITH ADDITIONAL COLLABORATION WITH NEIGHBORING OFFICES. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THROUGH 12Z...VFR CLEAR WITH SCT-BKN CLOUDS AOA 15000 FT ARRIVING SE PA AND S NJ SOUTHWARD AFTER 09Z. LIGHT NORTH NORTHWEST WIND. TODAY DURING THE DAY...SCT-BKN AOA 15000 FT MAY BRIEFLY THIN LATE IN THE DAY. LIGHT WEST - NORTHWEST WIND BECOMING WEST MIDDAY WITH GUSTS TO 15 KT POSSIBLE DURING THE AFTERNOON IN NJ/PA BUT SEABREEZES DEVELOP ALONG COASTAL SECTIONS MID AND LATE AFTN. TONIGHT...CIGS AOA 10000 FT, ESPECIALLY AFTER 03Z/26. A SPRINKLE POSSIBLE KPHL/KILG/KMIV KACY BUT NOT IN THE FCST ATTM. IT MAY BE TOO DRY IN THE LAYER UNDER 8000 FT. LIGHT WEST WIND SHIFTING N-NE DURING THE NIGHT. PLEASE SEE TAFS FOR TIMING DETAILS AS A WIND SHIFT BOUNDARY SAGS SOUTHWARD. OUTLOOK... SUNDAY...MAINLY VFR CONDITIONS, AS ANY SUB-VFR IN RAIN TO START ACROSS SOUTHERN AREAS WILL IMPROVE BACK TO VFR. MONDAY...MAINLY VFR CONDITIONS; ALTHOUGH, SOME ISOLATED SHOWERS ARE POSSIBLE. GUSTY NORTH TO NORTHWEST WINDS, WITH GUSTS TO 20 KNOTS. TUESDAY AND WEDNESDAY...MAINLY VFR EXPECTED; ALTHOUGH, CONDITIONS MAY DETERIORATE LATE WEDNESDAY NIGHT DEPENDING ON THE TIMING AND TRACK OF A POSSIBLE COASTAL LOW PRESSURE.
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&& .MARINE...
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DISCONTINUING SCA AT 330 AM. SUB SCA CONDITIONS THROUGH TONIGHT WITH NORTHWEST TO NORTHEAST WINDS THIS MORNING BECOMING WESTERLY MIDDAY THEN SEA BREEZES DURING LATE AFTERNOON. LIGHT WINDS TONIGHT BECOMING N-NE LATE. OUTLOOK... SUNDAY...SUB-ADVISORY CONDITIONS ARE EXPECTED AT THIS TIME. AN AREA OF LOW PRESSURE IS FORECAST TO PASS BY TO OUR SOUTH, BUT IT SHOULD NOT BE CLOSE ENOUGH TO RAISE WINDS OR SEAS TO SCA LEVELS. MONDAY...CONTINUED MAINLY SUB-SCA CONDITIONS; ALTHOUGH, SOME WIND GUSTS TO AROUND 20 KNOTS PLUS ARE POSSIBLE. TUESDAY AND WEDNESDAY...MOSTLY SUB-ADVISORY CONDITIONS THROUGH THIS PERIOD; ALTHOUGH, SOME HIGHER WINDS AND SEAS MAY BEGIN TO OCCUR LATE WEDNESDAY NIGHT DEPENDING ON THE TIMING AND TRACK OF POSSIBLE COASTAL LOW PRESSURE. LOW CONFIDENCE.
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&& .FIRE WEATHER...
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DRY CONDITIONS ARE EXPECTED ONCE AGAIN TODAY, WITH MINIMUM RH VALUES ONCE AGAIN RANGING FROM 20 TO 30 PERCENT. HOWEVER, WINDS WILL BE CONSIDERABLY LIGHTER, WITH GUSTS GENERALLY NEAR OR BELOW 15 MPH THROUGH THE DAY. NO ACTION ATTM.
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...FREEZE WARNING UNTIL 8 AM EDT THIS MORNING FOR PAZ060>062- 101>106. FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR PAZ070-071. NJ...FREEZE WARNING UNTIL 8 AM EDT THIS MORNING FOR NJZ001-007>010- 012-013-015>022-027. FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR NJZ014-023>026. DE...FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR DEZ001>004. MD...FREEZE WARNING UNTIL 8 AM EDT THIS MORNING FOR MDZ008. FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR MDZ012-015-019- 020. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR ANZ450>455.
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&& $$ SYNOPSIS...KLINE NEAR TERM...DRAG 3A SHORT TERM...DRAG 3A LONG TERM...KLINE AVIATION...DRAG/KLINE 3A MARINE...DRAG/KLINE 3A FIRE WEATHER...3A

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