Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 260942 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 542 AM EDT THU MAR 26 2015 .SYNOPSIS... LOW PRESSURE IN SOUTHERN OHIO WILL MOVE NORTHEASTWARD TODAY. ITS ASSOCIATED WARM FRONT WILL MOVE THROUGH THE REGION DURING THE FIRST PART OF THE DAY. THEN AS THE LOW CONTINUES TOWARD NEW ENGLAND, ITS ATTENDANT COLD FRONT WILL MOVE ACROSS THE MID ATLANTIC STATES TONIGHT. LOW PRESSURE MAY DEVELOP ON THAT FRONT OFF THE MID ATLANTIC COAST LATE FRIDAY AND HEAD NORTHEAST WELL OUT TO SEA SATURDAY. UNSEASONABLY STRONG CANADIAN HIGH PRESSURE BUILD INTO THE REGION FOR THE WEEKEND. AN AREA OF LOW PRESSURE IS EXPECTED TO TRACK TO OUR NORTH MONDAY, PULLING A COLD FRONT ACROSS THE AREA. MORE HIGH PRESSURE IS EXPECTED BEHIND THAT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THERE WAS SOME CLEARING OF THE LOW CLOUDS OVER EASTERN PENNSYLVANIA, NORTHEASTERN MARYLAND AND DELAWARE AROUND 530 AM. HOWEVER, THE LOW CLOUDS ARE EXPECTED TO EXPAND WESTWARD THIS MORNING AND CEILING HEIGHTS SHOULD LOWER AS ADDITIONAL MOISTURE IS DRAWN INTO OUR AREA ON THE SOUTHERLY FLOW. ALSO, MILD AIR WILL CONTINUE TO BUILD OVERHEAD STRENGTHENING THE TEMPERATURE INVERSION INTO THE MORNING HOURS. WE EXPECT SOME FOG TO DEVELOP IN THE TERRAIN OF EASTERN PENNSYLVANIA AND NORTHERN NEW JERSEY.THERE WAS ALREADY A FAIR AMOUNT OF FOG NEAR THE COAST AND OVER OUR COASTAL WATERS AND IT SHOULD PERSIST THROUGH MUCH OF THE MORNING. DEVELOPING RAIN SHOWERS OVER THE CHESAPEAKE BAY REGION AND THE CAROLINAS EARLY THIS MORNING WILL PROGRESS NORTHWARD AND THEY ARE FORECAST TO AFFECT OUR REGION FROM THIS MORNING INTO THE EARLY AFTERNOON HOURS. SOME SHOWERS WERE ALREADY INTO SOUTHERN AND CENTRAL DELAWARE AROUND 530 AM. THE BULK OF THE PRECIPITATION SHOULD PASS OVER THE COASTAL PLAIN AND OVER OUR COASTAL WATERS. DEVELOPING LIFT AND SUBTLE INSTABILITY MAY RESULT IN ISOLATED THUNDER WITHIN THE AREA OF SHOWERS. THE PROBABILITY OF RAIN SHOWERS MAY DECREASE FOR A TIME THIS AFTERNOON AFTER A WARM FRONT LIFTS THROUGH MUCH OF OUR REGION. THERE REMAINS SOME QUESTION AS TO WHETHER THE LOW LEVEL COOL AIR WILL SCOUR OUT OF OUR NORTHERN COUNTIES ENTIRELY. AS A RESULT, TODAY`S MAXIMUM TEMPERATURE FORECAST IS ONE OF LOW CONFIDENCE, ESPECIALLY IN THE NORTH. MEANWHILE, A STRENGTHENING LOW LEVEL JET WILL BE LOCATED OFF THE COASTS OF THE MIDDLE ATLANTIC STATES AND SOUTHERN NEW ENGLAND. THE LOW CLOUDS WILL LIKELY CLEAR FROM THE COASTAL PLAIN DUE TO FRICTIONAL EFFECTS FROM THE JET ALONG WITH THE STRONG LATE MARCH SUN. MAXIMUM TEMPERATURES AROUND 70 ARE ANTICIPATED FOR PARTS OF THE UPPER DELMARVA AND EXTREME SOUTHERN NEW JERSEY. THE WIND IS FORECAST START AS LIGHT AND VARIABLE AND IT SHOULD BECOME SOUTHERLY IN THE WAKE OF THE WARM FRONT AS THE BOUNDARY LIFTS GRADUALLY THROUGH OUR REGION TODAY. WE HAVE INDICATED A PERIOD OF LIGHT EASTERLY WINDS AHEAD OF THE WARM FRONT. RAINFALL TOTALS TODAY SHOULD BE LESS THAN A TENTH OF AN INCH IN MUCH OF OUR REGION. THE CONVECTIVE ACTIVITY DURING THE MORNING AND EARLY AFTERNOON COULD BRING LOCALIZED RAINFALL TOTALS OF A QUARTER TO A HALF INCH TO PARTS OF THE UPPER DELMARVA AND SOUTHERN NEW JERSEY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/... A COLD FRONT IS FORECAST TO WORK ITS WAY ACROSS OUR REGION FROM NORTHWEST TO SOUTHEAST BETWEEN ABOUT 800 PM AND 200 AM. SHOWERS ARE EXPECTED WITH AND BEHIND THE BOUNDARY. INSTABILITY SHOULD BE RATHER LIMITED. HOWEVER, IT IS A ROBUST FRONTAL BOUNDARY AND SCATTERED THUNDER REMAINS POSSIBLE. STRONG COLD ADVECTION WILL TAKE PLACE FOLLOWING THE FRONTAL PASSAGE AND TEMPERATURES SHOULD FALL INTO THE 40S BY DAYBREAK ON FRIDAY. READINGS ARE EXPECTED TO DROP INTO THE 30S IN OUR NORTHERN COUNTIES AND ANY LINGERING RAIN SHOWERS COULD CHANGE TO SNOW THERE. HOWEVER, ANY SNOWFALL ACCUMULATIONS SHOULD BE NEGLIGIBLE AS PRECIPITATION RATES CONTINUE TO DIMINISH LATE TONIGHT. RAINFALL TOTALS WITH THE FRONTAL SYSTEM ARE FORECAST TO BE GENERALLY A QUARTER INCH OR LESS. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... THE COLD FRONT WILL BE OFF THE COAST FRI MRNG AND PRECIP WILL BE COMING TO AN END FROM W TO E DURG THE COURSE OF THE MRNG HOURS. PRECIP WILL LINGER LONGEST OVER SRN AND ERN SECTIONS WHERE IT CUD LINGER INTO ERLY AFTN. THE MDLS HAVE COME INTO BETTER AGREEMENT WITH THIS SCENARIO TODAY, AND MOST IF NOT ALL OF THE PRECIP SHUD BE OVER WITH BY 00Z SAT WITH EXCEPT FOR PSBLY THE DELMARVA. LOW PRES IS THEN EXPECTED TO FORM ON THE CDFNT TO THE E FRI NIGHT INTO SAT AS STRONG HIGH PRES BUILDS DOWN FROM CAN ACRS THE UPPER MIDWEST. A WEAK SFC TROF MAY DEVELOP ON THE WRN SIDE OF THE TROF AND MOVE ACRS THE REGION BEFORE THE HIGH BUILDS IN AND THIS TROF COUPLED WITH AN UNSEASONABLY DEEP H5 TROF COULD TRIGGER SOME INSTABILITY SHWRS/SNOW SHOWERS ON SAT, ESPECIALLY ACRS THE N. SO, WILL CARRY SOME LOW POPS. THE LARGE HIGH THEN MOVE OVER THE AREA SAT NIGHT INTO SUN AND CONDS DRY OUT. THE HIGH THEN MOVES OFF THE COAST SUN NIGHT AS LOW PRES TREKS ACRS SRN CANADA. THIS LOW WILL BRING A WK CDFNT ACRS NEW ENG AND ITS SRN EXTENT MAY BRUSH OUR NRN ZONES. THE FRONT WILL NOT HAVE MUCH MOISTURE WITH IT, BUT CUD TRIGGER SOME PRECIP WITH IT MON INTO MON NIGHT. THEN, THERE IS SOME DISAGREEMENT BETWEEN THE GFS AND ECMWF WITH REGARD TO TUE. THE GFS KEEPS THINGS DRY WITH WK HIGH PRES. THIS CONTINUES INTO ERLY WED BEFORE LOW PRES APPROACHES. ON THE OTHER HAND, THE ECMWF WANTS TO BRING A WK AREA OF LOW PRES ACRS THE REGION LATER TUE INTO TUE NIGHT THEN KEEPS WED DRY. THE CMC IS SOMEWHERE IN THE MIDDLE. SO, FOR RIGHT NOW, WILL MAINTAIN A DRY FCST TUE AND KEEP LOW POPS ON WED AND SEE HOW THINGS DEVELOP. TEMPS WILL START OFF AROUND NRML ON FRI THEN PLUMMET BEHIND THE CFP FOR SAT AND SUN. TEMPS WILL AVERAGE 10 TO 15 DEGREES BELOW NRML OVER THE WEEKEND BEFORE RETURNING TO NR NRML ON MON. THEY WILL DROP A BIT FOR TUE BEHIND THE WK FRONT THEN BOUNCE BACK AGAIN NR MIDWEEK. && .AVIATION /10Z THURSDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. WE WILL KEEP THE MENTION OF LOW LEVEL WIND SHEAR FOR KMIV AND KACY THIS MORNING DUE TO THE LOW LEVEL SOUTHWESTERLY WIND JET LOCATED NEAR THE COAST. CONDITIONS WERE IFR AT KTTN, KPNE AND KACY AROUND 0930Z AND THEY WERE GENERALLY MVFR AT OUR REMAINING FIVE TAF SITES. CONDITIONS ARE EXPECTED TO LOWER INTO THE IFR CATEGORY THIS MORNING AT KPHL, KILG, KMIV, KRDG AND KABE WITH AN AREA OF SHOWERS LIFTING NORTHWARD AND AFFECTING MAINLY KPHL AND POINTS TO THE SOUTH AND EAST. ISOLATED THUNDER IS POSSIBLE BUT THE PROBABILITY IS NOT GREAT ENOUGH TO INCLUDE IN THE TAFS. SOME IMPROVEMENT INTO THE MVFR CATEGORY IS ANTICIPATED FOR THIS AFTERNOON AS A WARM FRONT CONTINUES TO LIFT THROUGH OUR REGION. A COLD FRONT FROM THE NORTHWEST IS FORECAST TO PASS ACROSS OUR TAF SITES BETWEEN ABOUT 0100Z AND 0500Z. IT WILL BRING ADDITIONAL SHOWERS AND LOW CONDITIONS. AGAIN, THERE IS A LOW CHANCE OF THUNDER AT THAT TIME BUT IT IS NOT MENTIONED IN THE TAFS. CONDITIONS SHOULD REMAIN MVFR FOR LATE TONIGHT AS THE RAIN SHOWER ACTIVITY BEGINS TO DIMINISH. A LIGHT AND VARIABLE WIND THIS MORNING MAY BEGIN TO FAVOR THE EAST AROUND 4 TO 6 KNOTS IN ADVANCE OF THE WARM FRONT. THE WIND SHOULD BECOME SOUTHERLY AFTER THE FRONT PASSES AND IT IS EXPECTED TO INCREASE TO AROUND 10 TO 14 KNOTS WITH GUSTS INTO THE 20S. THE WIND IS ANTICIPATED TO DECREASE A BIT THIS EVENING THEN IT WILL SHIFT TO THE NORTHWEST FOLLOWING THE PASSAGE OF THE COLD FRONT. OUTLOOK... FRI-FRI NIGHT...MOSTLY VFR EXPECTED. SCATTERED SHWR PSBL WITH LWR CONDS MAINLY E ERLY. MDT TO HIGH CONFIDENCE. SAT-SAT NIGHT...MOSTLY VFR EXPECTED. SCATTERED SHRA OR SHSN N PSBL. HIGH CONFIDENCE. SUNDAY...VFR. HIGH PRESSURE. HIGH CONFIDENCE. SUNDAY NIGHT-MONDAY...MOSTLY VFR. ISOLATED SHRA/SHSN MAINLY N AND W PSBL. HIGH CONFIDENCE. && .MARINE... A STRENGTHENING LOW LEVEL JET IS FORECAST TO REMAIN OVER OUR COASTAL WATERS TODAY BEFORE IT DRIFTS OUT TO SEA TONIGHT. HOWEVER, BEING THAT THE WATER TEMPERATURE REMAINS QUITE COLD AND THE AIR ADVECTING NORTHEASTWARD WITH THE LOW LEVEL JET IS RATHER MILD, MOMENTUM TRANSFER WILL BE LIMITED. WE ARE ANTICIPATING THAT GUSTS MAY REACH ONLY 25 OR 30 KNOTS EVEN AS THE LOW LEVEL JET SPEEDS INCREASE TO 50 OR 60 KNOTS TODAY. A SURFACE WARM FRONT WILL LIFT ACROSS THE COASTAL WATERS OF NEW JERSEY AND DELAWARE THIS MORNING. AREAS OF FOG WILL PERSIST UNTIL THE BOUNDARY ARRIVES. THE VISIBILITY WILL BE A HALF MILE OR LESS OVER THE WATER. A COLD FRONT FROM THE NORTHWEST WILL ARRIVE TONIGHT. WE WILL KEEP THE SMALL CRAFT ADVISORY IN PLACE FOR WIND GUSTS AROUND 25 KNOTS AND FOR WAVE HEIGHTS ON OUR OCEAN WATERS BUILDING TO 5 TO 8 FEET. OUTLOOK... FRI...SCA CONDS REMAIN ON THE OCEAN DUE TO ELEVATED SEAS. FRI NIGHT THRU SAT NIGHT...WIND AND SEAS MAY ONCE AGAIN APPROACH SCA CONDS ON STRONG NWLY FLOW. CONDS APPEAR MARGINAL, BUT ADDITIONAL FLAGS MAY BE NEEDED FOR A PORTION OF THIS TIME FRAME. SUN...NO MARINE HEADLINES ANTICIPATED AS CONDS DECREASE TO BELOW SCA CONDS. SUN NIGHT-MON...WINDS AND SEAS INCREASE OVERNIGHT TO AT LEAST SMALL CRAFT ADVISORY LEVELS, POSSIBLY NEAR GALE FORCE AS ANOTHER FRONT APPROACHES AND STRONG HIGH PRES MOVES OFF THE COAST. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT FRIDAY FOR ANZ450>455. SMALL CRAFT ADVISORY UNTIL 8 AM EDT FRIDAY FOR ANZ430-431. && $$ SYNOPSIS...NIERENBERG NEAR TERM...IOVINO SHORT TERM...IOVINO LONG TERM...NIERENBERG AVIATION...IOVINO/NIERENBERG MARINE...IOVINO/NIERENBERG

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