Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 250748 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 348 AM EDT MON APR 25 2016 .SYNOPSIS...
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HIGH PRESSURE CENTERED OFF THE MIDDLE ATLANTIC COAST THIS MORNING WILL CONTINUE TO LOSE ITS INFLUENCE OVER OUR WEATHER TODAY AS IT DRIFTS TO THE SOUTHEAST. A COLD FRONT IS FORECAST TO DROP SLOWLY SOUTHWARD ACROSS EASTERN PENNSYLVANIA, NEW JERSEY, NORTHEASTERN MARYLAND AND DELAWARE ON TUESDAY AND TUESDAY NIGHT. HIGH PRESSURE IS EXPECTED TO NOSE DOWN FROM THE NORTHWEST FOR WEDNESDAY. LOW PRESSURE IS ANTICIPATED TO APPROACH FROM THE WEST ON THURSDAY BEFORE SLIDING OFF THE MIDDLE ATLANTIC COAST ON THURSDAY NIGHT AND MOVING OUT TO SEA ON FRIDAY. AN AREA OF HIGH PRESSURE IS EXPECTED TO FOLLOW ON SATURDAY WITH ANOTHER LOW FORECAST TO APPROACH FROM THE WEST ON SUNDAY.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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HIGH PRESSURE THAT HAD BEEN IN CONTROL OF THE WEATHER, BRINGING SIGNIFICANTLY DRY CONDITIONS TO THE AREA HAS MOVED OFFSHORE. WITH THE HIGH OFFSHORE, A RETURN FLOW HAS DEVELOPED, WHICH WILL ALLOW FOR DEW POINTS TO INCREASE TODAY ACROSS THE AREA. AN AREA OF MID LEVEL CLOUD COVER ASSOCIATED WITH A VORTICITY IMPULSE APPROACHING FROM THE NORTHWEST IS SLIDING ACROSS THE NORTHERN HALF OF THE AREA THIS MORNING. THIS CLOUD COVER WILL LIKELY REMAIN FOR MUCH OF THE DAY, UNTIL A WARM FRONT LIFTS ACROSS THE AREA FROM THE WEST AND BRINGS SOME LOWER CLOUDS TO THE AREA. WE DO NOT EXPECT ANY PRECIPITATION THROUGH THE DAYLIGHT HOURS ACROSS THE AREA, DESPITE THE APPROACHING VORT MAX AND THE LIFTING WARM FRONT. WITH INCREASING THICKNESSES AND 925MB TEMPERATURES, HIGHS TODAY WILL RISE SEVERAL DEGREES ABOVE NORMAL. WE RAISED TEMPERATURES BY A COUPLE OF DEGREES ABOVE A BLEND OF MOS.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
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A WARM FRONT WILL CONTINUE SLOWLY LIFTING ACROSS THE AREA OVERNIGHT TONIGHT, WHILE AN AREA OF LOW PRESSURE RIDES ALONG THE FRONT AND APPROACHES FROM THE WEST OVERNIGHT. A COUPLE OF VORTICITY IMPULSES ARE EXPECTED TO SLIDE ACROSS THE AREA OVERNIGHT, WITH THE STRONGEST AFTER MIDNIGHT AND THROUGH DAYBREAK. WHILE THERE COULD BE SOME LIGHT SHOWERS DEVELOP DURING THE EVENING, WE EXPECT THE BEST CHANCE FOR SHOWERS AFTER MIDNIGHT AND THROUGH DAYBREAK WITH THE STRONGER OF THE VORTICITY IMPULSES. THERE IS SOME INSTABILITY FORECAST TO DEVELOP AND SPREAD ACROSS THE AREA, SO IT IS POSSIBLE FOR A FEW ISOLATED THUNDERSTORMS TO DEVELOP OVERNIGHT.
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&& .LONG TERM /TUESDAY THROUGH SUNDAY/...
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THE LATEST GUIDANCE SUGGESTS THAT A FRONTAL BOUNDARY WILL EXTEND EASTWARD FROM LOWER MICHIGAN TO NORTHERN PENNSYLVANIA, NORTHERN NEW JERSEY AND THE WATERS OFF LONG ISLAND EARLY ON TUESDAY MORNING. WEAK AREAS OF LOW PRESSURE ARE FORECAST TO RIDE ALONG THE FRONT SLOWING ITS PROGRESS. THE SEGMENT OF THE BOUNDARY IN OUR REGION IS EXPECTED TO EASE SOUTHWARD ON TUESDAY, REACHING SOUTHEASTERN PENNSYLVANIA AND CENTRAL NEW JERSEY LATE IN THE DAY. IT IS NOT ANTICIPATED TO PASS SOUTHERN DELAWARE AND ITS COASTAL WATERS UNTIL CLOSE TO DAYBREAK ON WEDNESDAY. WE EXPECT SHOWERS AND A CHANCE OF THUNDERSTORMS ON TUESDAY INTO TUESDAY NIGHT. THE POTENTIAL FOR THUNDER IS GREATEST ALONG AND AHEAD OF THE BOUNDARY WHERE TEMPERATURES SHOULD RISE NEAR 80 DEGREES ON TUESDAY WITH DEW POINT READINGS AROUND 60. MIXED LAYER CAPE VALUES ARE ANTICIPATED TO INCREASE AROUND 1000 J/KG. A LOW LEVEL WESTERLY JET IN EXCESS OF 40 KNOTS AND A MID LEVEL SHORT WAVE TROUGH APPROACHING FROM THE NORTHWEST SHOULD HELP TO ENHANCE THE CONVECTIVE POTENTIAL. THERE IS A MARGINAL THREAT FOR SEVERE THUNDERSTORMS IN MUCH OF OUR REGION AS INDICATED BY THE STORM PREDICTION CENTER`S CONVECTIVE OUTLOOK. WE WILL KEEP THE MENTION OF THIS POSSIBILITY IN OUR HAZARDOUS WEATHER OUTLOOK. HIGH PRESSURE AND DRY AIR ARE FORECAST TO NOSE DOWN FROM THE NORTHWEST FOR WEDNESDAY. HOWEVER, SOME CLOUDS MAY LINGER OVER OUR SOUTHERN COUNTIES WITH THE FRONTAL BOUNDARY EXPECTED TO STALL NEAR THE VIRGINIA AND NORTH CAROLINA BORDER. AN AREA OF LOW PRESSURE APPROACHING FROM THE WEST IS ANTICIPATED TO RIDE ALONG THE FRONTAL BOUNDARY AND IT SHOULD SPREAD CLOUDS AND SHOWERS BACK INTO OUR REGION FOR THURSDAY AND FRIDAY. THERE REMAINS A BIT OF DISAGREEMENT AMONG THE MODELS REGARDING THE NORTHERN EXTENT OF THE SHOWERS, SO WE WILL KEEP OUR FORECAST PROBABILITIES IN THE CHANCE CATEGORY. IT APPEARS AS THOUGH SOME DRYING WILL WORK ITS WAY DOWN FROM THE NORTHWEST FOR SATURDAY. HOWEVER, ANOTHER SURFACE LOW BEING DRIVEN BY THE PROGRESSIVE MID LEVEL PATTERN MAY APPROACH FROM THE WEST ON SUNDAY. FOLLOWING TUESDAY`S ABOVE NORMAL TEMPERATURES, READINGS SHOULD REMAIN NEAR NORMAL FOR THE PERIOD FROM WEDNESDAY THROUGH SUNDAY.
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&& .AVIATION /08Z MONDAY THROUGH FRIDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS ARE EXPECTED FOR TODAY ACROSS THE AREA. AN AREA OF MID LEVEL CLOUDS WILL CONTINUE ACROSS THE NORTHERN HALF OF THE AREA THROUGH THE MORNING, BEFORE SOME LOWER CLOUDS DEVELOP AND SPREAD ACROSS THE AREA AS A WARM FRONT APPROACHES LATER IN THE DAY. THE WARM FRONT WILL SLOWLY LIFT THROUGH THE NORTHERN HALF OF THE AREA TONIGHT, WHICH COULD BRING SOME SCATTERED SHOWERS ACROSS THE TAF SITES, ESPECIALLY ABE, RDG, TTN. IT IS ALSO POSSIBLE WITH AN INCREASE IN MOISTURE OVERNIGHT, THAT SOME MVFR VSBYS MAY DEVELOP ACROSS THE TAF SITES, EVEN OUTSIDE OF WHERE SHOWERS OCCUR, SO THIS MAY BE INTRODUCED WITH THE NEXT SET OF TAFS. LIGHT AND VARIABLE WINDS EARLY WILL BECOME SOUTHWEST LATER THIS MORNING. THERE COULD BE SOME GUSTS AROUND MIDDAY AROUND THE MID TEENS ACROSS THE SOUTHERN HALF OF THE AREA. THE WINDS ACROSS THE NORTHERN TAF SITES MAY BECOME MORE SOUTHEASTERLY OVERNIGHT AS THE WARM FRONT LIFTS THROUGH THE AREA. OUTLOOK... TUESDAY INTO TUESDAY EVENING...RAIN SHOWERS ARE EXPECTED ALONG WITH A CHANCE OF THUNDERSTORMS. CEILING AND VISIBILITY VALUES WILL DROP INTO THE MVFR CATEGORY AND POSSIBLY BECOME IFR AT TIMES. LATE TUESDAY NIGHT INTO WEDNESDAY NIGHT...MAINLY VFR. THURSDAY THROUGH FRIDAY...A CHANCE OF SHOWERS. CEILING AND VISIBILITY VALUES MAY DROP INTO THE MVFR CATEGORY AT TIMES.
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&& .MARINE...
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SUB-SMALL CRAFT ADVISORY CONDITIONS WILL REMAIN ACROSS THE WATERS TODAY AND THROUGH THE FIRST HALF OF THE NIGHT. DESPITE A TIGHTENING PRESSURE GRADIENT AS THE HIGH OFFSHORE SLOWLY MOVES AWAY AND THE APPROACHING WARM FRONT, WE ARE NOT EXPECTING THE STRONGER WINDS FROM ALOFT TO MIX DOWN TO THE SURFACE WITH A DEVELOPING INVERSION ACROSS THE WATERS. HOWEVER, WITHIN THE SOUTHERLY FLOW, SEAS COULD BUILD TO 5 FEET OVERNIGHT, SO WE HAVE DECIDED TO ISSUE A SMALL CRAFT ADVISORY STARTING AT MIDNIGHT FOR THE ATLANTIC COASTAL WATERS. OUTLOOK... TUESDAY...A SMALL CRAFT ADVISORY IS IN EFFECT FOR OUR OCEAN WATERS. SOUTHWESTERLY WINDS SHOULD GUST NEAR 25 KNOTS, ESPECIALLY IN THE MORNING, AND WAVE HEIGHTS ARE FORECAST TO BE AROUND 5 FEET. TUESDAY NIGHT...A SMALL CRAFT ADVISORY IS IN EFFECT FOR OUR OCEAN WATERS. NORTHEASTERLY WINDS MAY GUST NEAR 25 KNOTS, ESPECIALLY AFTER MIDNIGHT, AND WAVE HEIGHTS ARE EXPECTED TO BE AROUND 5 FEET. THE SMALL CRAFT ADVISORY IS IN EFFECT ONLY UNTIL MIDNIGHT. HOWEVER, IT MAY NEED TO BE EXTENDED IF THE FORECAST CONFIDENCE FOR THE NORTHEASTERLY WIND GUSTS INCREASES. WEDNESDAY THROUGH THURSDAY NIGHT...NO MARINE HEADLINES ARE ANTICIPATED. FRIDAY...WAVE HEIGHTS MAY BUILD NEAR 5 FEET ON OUR OCEAN WATERS IN A NORTHEASTERLY SURFACE FLOW.
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&& .FIRE WEATHER...
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT EDT TUESDAY NIGHT FOR ANZ450>455.
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&& $$ SYNOPSIS...IOVINO NEAR TERM...ROBERTSON SHORT TERM...ROBERTSON LONG TERM...IOVINO AVIATION...IOVINO/ROBERTSON MARINE...IOVINO/ROBERTSON FIRE WEATHER...ROBERTSON

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