Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 291403 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1003 AM EDT WED OCT 29 2014 .SYNOPSIS... A COLD FRONT WILL MOVE ACROSS THE AREA TODAY, THEN HIGH PRESSURE WILL BRIEFLY AFFECT THE AREA THURSDAY. AN AREA OF LOW PRESSURE WILL MOVE OUT OF THE GREAT LAKES REGION AND SOUTH OF THE AREA ON FRIDAY, BEFORE COMBINING WITH A DEVELOPING AND STRENGTHENING COASTAL LOW OFFSHORE OF THE MID ATLANTIC COAST SATURDAY. THIS LOW WILL MOVE WELL NORTHEAST OF THE AREA ON SUNDAY, THEN HIGH PRESSURE IS EXPECTED TO BUILD BACK ACROSS THE EAST COAST MONDAY, THEN OFFSHORE TUESDAY AHEAD OF AN APPROACHING FRONTAL SYSTEM. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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MOUNT HOLLY IS ALSO SERVICE BACKING UP STERLING THROUGH 4 PM TODAY. YOU`LL SEE STERLING FORECAST PRODUCTS ISSUED BY NWS MOUNT HOLLY. 930 AM ESTF: NO SIGNIFICANT CHANGES TO THE PRIOR FORECAST FOR TODAY. HOWEVER A WORD OF CAUTION...THE CURRENT HOURLY TEMPS OVER E PA AND NE MD IN RAIN COOLING THE AIR TEMP (WET BULBING) MAY BE 5 DEGREES TOO WARM IN EASTERN PA DURING MID AFTN (NEAR 52 DEGREES INSTEAD OF THE HOURLY UPPER 50S-NEAR 60 TEMPS AS POSTED AT 930AM). ONCE WE`RE MORE CONFIDENT...WE MAY RAISE POPS 30-40 PCT FOR THIS AFTN IN E PA TO CATEGORICAL AND LOWER MID AFTN TEMPS...WONT KNOW MUCH MORE TILL 11 AM OR NOON. 12Z NAM IS STARTING TO MIRROR THE WETTER HEAVIER 06Z/29 GFS. A COLD FRONT COLD FRONT WILL CONTINUE TO PROGRESS EASTWARD THRU EASTERN PA THIS MORNING AND OFF THE COAST EARLY THIS AFTERNOON. BASED ON LATEST MODEL GUIDANCE AND OBSERVATIONS, THE TREND WAS TO SLOW DOWN THE ARRIVAL OF THE SHOWERS AS THE SEPARATION DISTANCE BETWEEN THE FRONT AND POST-FRONTAL LIFT FROM THE MID-LEVEL TROUGH GROWS. MADE NOTABLE CHANGES TO THE POP/WX GRIDS TO TAKE THE DELAY INTO ACCOUNT. SHOWERS NOT EXPECTED TO BE WIDESPREAD AND RAINFALL AMOUNTS WILL BE LIGHT (GENERALLY UNDER ONE THIRD INCH). ISOLATED SLIGHTLY HIGHER AMOUNTS POSSIBLE LATE THIS AFTERNOON AS A WEAK DISTURBANCE TRAILING THE FRONT IS FORECAST TO TRACKS FROM VA TO THE DELMARVA, LEADING TO AN ENHANCEMENT OF PRECIP OVER THE SOUTHEASTERN PART OF THE CWA.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/... THE COLD FRONT WILL CONTINUE TO MOVE OFF THE EAST COAST TONIGHT. THE BACK EDGE OF THE LINGERING SHOWERS BEHIND THE BOUNDARY SHOULD BE SHIFTING THRU THE I-95 CORRIDOR EARLY THIS EVENING AND OFF THE NJ/DE COAST AROUND MIDNIGHT. WEST-NORTHWEST WINDS BEHIND THE FRONT WILL ADVECT COLDER AND EVENTUALLY DRIER AIR INTO THE REGION. SKIES WILL CLEAR NOT TOO LONG AFTER PRECIP ENDS- DURING THE EVENING ACROSS EASTERN PA AND NORTHWEST NJ AND OVERNIGHT FOR COASTAL AREAS. THE PRESSURE GRADIENT WILL BE STRONG ENOUGH FOR A 5-10 MPH WIND TO CONTINUE OVERNIGHT ESPECIALLY WITH CAA AIDING IN A MIXED NOCTURNAL BOUNDARY LAYER. THEREFORE, WENT A COUPLE OF DEGREES ABOVE A MAV/MET BLEND FOR MIN TEMPS. && .LONG TERM /THURSDAY THROUGH TUESDAY/... HIGH PRESSURE IS EXPECTED TO BRIEFLY AFFECT THE AREA THURSDAY INTO THURSDAY NIGHT. DRY WEATHER AND NEAR NORMAL TEMPERATURES ARE EXPECTED BEFORE A DECLINE IN THE WEATHER FOR THE UPCOMING WEEKEND. ON FRIDAY, AN AREA OF LOW PRESSURE WILL BE MOVING OUT OF THE GREAT LAKES REGION, AND IS EXPECTED TO MOVE TO THE SOUTH OF THE AREA WHILE A COASTAL LOW DEVELOPS AND STRENGTHENS TO OUR SOUTH. WE DO NOT EXPECT MUCH, IF ANY PRECIPITATION DURING THE DAY AS THE PRECIPITATION TIED TO THE SYSTEM TO OUR WEST SHOULD REMAIN TO OUR NORTH AND WEST UNDERNEATH THE MID/UPPER LOW/TROUGH. AS WE GO INTO FRIDAY NIGHT, THE MID/UPPER LOW WILL SWING TO OUR SOUTH, WHILE THE SURFACE LOW WILL BEGIN GETTING ABSORBED BY THE COASTAL LOW. THIS WILL ALLOW SOME LIGHT PRECIPITATION TO FILL IN ACROSS THE AREA AS THE MAJORITY OF THE MODEL GUIDANCE IS INDICATING. IT LOOKS LIKE ANY PRECIPITATION THAT STARTS OUT FRIDAY NIGHT SHOULD BE MOSTLY A COLD RAIN AS MODELS NOW KEEP 925/850 MB TEMPS ABOVE FREEZING, ALTHOUGH IT IS STILL POSSIBLE FOR A MIXTURE ACROSS THE FAR NORTHERN AREAS. THE MID/UPPER TROUGH WILL SWING OFFSHORE OF THE NORTH CAROLINA COAST SATURDAY, WHICH WILL ALLOW THE SURFACE LOW TO STRENGTHEN AND WRAP UP MORE. THE GFS KEEPS THE PRECIP CLOSE TO THE SURFACE AND MID-LEVEL LOW AND MOSTLY OFFSHORE, BUT THE ECMWF AND CANADIAN KEEP PRECIP ACROSS THE ENTIRE AREA AND EXTEND IT PRETTY FAR TO OUR NORTHWEST, SO WE WILL KEEP A CHANCE OF SHOWERS THROUGH THE DAY SATURDAY. THE MODELS DO SHOW THE PRECIP MOVING TO OUR NORTHEAST OVERNIGHT SATURDAY AS THE SURFACE AND MID/UPPER LOW PULL TO OUR NORTHEAST, SO WE`LL HAVE DECREASING POPS OVERNIGHT. THE MODELS KEEP THE SUB-FREEZING TEMPERATURES OUT OF THE AREA UNTIL OVERNIGHT SATURDAY, SO THE BEST CHANCE FOR A MIX OR COMPLETE CHANGE OVER TO SNOW WILL BE SATURDAY NIGHT INTO SUNDAY MORNING IF THERE IS STILL ANY REMAINING PRECIPITATION, MAINLY ACROSS THE NORTHERN THIRD OF THE AREA. WINDS WILL INCREASE SATURDAY INTO SATURDAY NIGHT AS THE PRESSURE GRADIENT TIGHTENS SIGNIFICANTLY BETWEEN THE COASTAL LOW AND HIGH PRESSURE TO THE WEST. WINDS LOOK TO GUST BETWEEN 30-40 MPH, WITH HIGHER GUSTS POSSIBLE CLOSER TO THE COAST. SUNDAY IS EXPECTED TO BE DRY, BUT COLD AND BLUSTERY AS A STIFF NORTHWEST FLOW IS EXPECTED AS THE LOW PRESSURE STRENGTHENS TO OUR NORTHEAST AND HIGH PRESSURE BEGINS APPROACHING FROM THE WEST. WINDS COULD CONTINUE TO GUST 30-40 MPH ACROSS THE AREA. HIGH PRESSURE IS EXPECTED TO BUILD TO OUR SOUTH MONDAY AND NOSE ITS WAY INTO OUR AREA. THIS WILL PROVIDE FAIR WEATHER WITH TEMPERATURES RISING BACK CLOSER TO NORMAL. ON TUESDAY, THE HIGH IS EXPECTED TO BUILD OFFSHORE OF THE SOUTHEAST COAST, WHILE A WARM FRONT LIFTS NORTH OF THE AREA AHEAD OF THE NEXT APPROACHING COLD FRONT. AS OF NOW, THE FORECAST FOR TUESDAY IS FOR DRY WEATHER WITH WARMING TEMPERATURES, ALTHOUGH IF THE WARM FRONT PASSES CLOSE ENOUGH, A FEW SHOWERS MAY BE POSSIBLE. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. FOR MOUNT HOLLY: TODAY...PREDOMINATELY VFR CIGS TODAY AOA 5000 FT. A BRIEF PERIOD OF MVFR CIGS/VSBYS POSSIBLE WITH HEAVIER SHRA BEHIND A COLD FRONT BUT CONFIDENCE FOR MVFR CONDS IS VERY LOW AT THIS TIME. LATEST HIGH RES SHORT TERM GUIDANCE AND THE 12Z NAM ARE SUGGESTING SHOWERS MAY NOT ARRIVE KACY AND KMIV TIL AROUND 21Z AND MAY LINGER THROUGH 01Z THIS EVENING. LIGHT SHIFTING WIND TURNING W TO NW AND BRIEFLY GUSTING 20 KT BEHIND THE COLD FRONTAL PASSAGE. TONIGHT...VFR CIGS CLEARING FROM WEST TO EAST WITH LEFTOVER RAIN KACY/KMIV AND SE DELAWARE ENDING BY 03Z/30. LIGHT NORTHWEST WIND. FOR STERLING: NWS MOUNT HOLLY IS BACKING UP THIS OFFICE AND THEIR TAFS THROUGH 20Z TODAY. ALL TAFS WERE AMENDED BETWEEN 930 AND 10AM FOR A DELAY IN SHOWERS AND/OR ADDITIONAL TAF INFO BEYOND 24 HOURS. TODAY...VFR CIGS. CDFNT CROSSING TERMINALS TDA. THE WSHFT TO NW WILL COME FIRST...AND IS IN PROGRESS NOW THROUGH KBWI KDCA. SHOWERS WILL FOLLOW THE WIND SHIFT BY ABOUT 2-4 HOURS AND BRIEF MVFR CONDS POSSIBLE IN A HEAVIER SHOWER. TONIGHT...CLEARING WITH A LIGHT NW WIND. OUTLOOK... THURSDAY-FRIDAY...MOSTLY VFR. FRIDAY NIGHT-SATURDAY NIGHT...LOWER END VFR OR UPPER END MVFR WITH CIGS 2,500-3,500 EXPECTED. LOWER VSBYS POSSIBLE WITH RAIN SHOWERS. SNOW SHOWERS POSSIBLE ACROSS NORTHEAST PENNSYLVANIA AND NORTHWEST NEW JERSEY. GUSTY NORTH-NORTHWEST WINDS SATURDAY INTO SATURDAY NIGHT 25-30 KNOTS, POSSIBLY HIGHER NEAR THE COAST. SUNDAY...VFR. GUSTY NORTHWEST WINDS 25-30 KNOTS.
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&& .MARINE...
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NO HEADLINES THROUGH TONIGHT. SW WIND 10-15 KT SHIFTING WNW LATER THIS AFTERNOON WITH A GUST TO 20 KT POSSIBLE. NW WIND TONIGHT AT 10 TO 15 KT. OUTLOOK... THURSDAY-FRIDAY NIGHT...SUB-SMALL CRAFT ADVISORY CONDITIONS EXPECTED, ALTHOUGH WINDS A SEAS WILL BE INCREASING LATE FRIDAY NIGHT. SATURDAY-SATURDAY NIGHT...INCREASING WINDS SATURDAY AND SATURDAY NIGHT AS A COASTAL LOW STRENGTHENS. GALE FORCE WINDS LOOKING MORE LIKELY. SUNDAY...GALE FORCE WINDS POSSIBLE EARLY, BEFORE DIMINISHING TO SMALL CRAFT ADVISORY LEVELS LATE IN THE DAY.
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&& .EQUIPMENT...
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SERVICE BACKUP FOR STERLING - LWX TODAY. HAVE LISTED THIS UNDER EQUIPMENT...JUST IN CASE THIS SERVICE BACKUP MESSAGE IS MISSED IN THE NEAR TERM AND AVIATION SECTION.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...ROBERTSON NEAR TERM...DRAG/KLEIN 1003A SHORT TERM...KLEIN LONG TERM...ROBERTSON AVIATION...DRAG/ROBERTSON 1003A MARINE...DRAG/ROBERTSON 1003A EQUIPMENT...

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