Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 280518 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1218 AM EST SUN DEC 28 2014 .SYNOPSIS...
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A COLD FRONT WILL CROSS THE AREA TOMORROW, THEN STALL TO OUR SOUTH AS A WEAK LOW PRESSURE SYSTEM RIDES ALONG IT MONDAY AND MONDAY NIGHT. IN THE WAKE OF THE FRONT, A COLD AIR MASS SLIDES SOUTH AND SETTLES IN OVER THE REGION THROUGH NEW YEARS DAY. ON FRIDAY, A LOW PRESSURE SYSTEM COULD DEVELOP OVER THE SOUTHERN PLAINS AND BEGIN LIFTING NORTHEAST TOWARDS THE REGION TO START THE WEEKEND.
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&& .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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NO BIG CHANGES WITH THIS UPDATE EITHER, JUST SLIGHT POP ADJUSTMENTS BASED ON LATEST RAP AND HRRR BLEND. OVERALL, NO BIG CHANGES TO THE FORECAST TONIGHT. MOSTLY HOURLY GRID ADJUSTMENTS MADE, BUT WE DID MAKE SOME CHANGES TO THE OVERNIGHT LOWS FOR SOME AREAS. MAINLY PORTIONS OF THE PINE BARRENS AND NORTHERN NEW JERSEY WHERE TEMPERATURES HAVE ALREADY RADIATED QUITE EFFICIENTLY. OTHERWISE, FORECAST LOOKS ON TRACK. LIGHT SOUTHWESTERLY WINDS WILL CONTINUE TO USHER IN A SOMEWHAT MOISTER AIRMASS, AHEAD OF AN APPROACHING COLD FRONT. SKIES WILL CONTINUE TO THICKEN AND LOWER WITH TIME. THE POSITION OF THE FRONT LOOKS TO BE JUST TO OUR WEST RIGHT AROUND SUNRISE SUNDAY MORNING...THIS IS WHEN WE INCREASE POPS INTO THE LIKELY RANGE. THERMAL PROFILES SHOW ALL AN LIQUID PTYPE FOR THE REGION AS SURFACE TEMPERATURES WILL ONLY DROP INTO THE MID TO UPPER-30S IN A LOT OF PLACES EXCEPT WHERE THEY HAVE RADIATED MORE ALREADY.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/... COLD FRONT WILL WORK ITS WAY THROUGH THE REGION FROM LATE MORNING THROUGH THE EVENING HOURS. HAVE INCREASE POPS TO CATEGORICAL FOR AT LEAST THE SOUTHERN HALF OF THE CWA BY SUNDAY AFTERNOON. SOME WEAK MID-LEVEL ENERGY SLIDES ALONG THE FRONT LATER TOMORROW AFTERNOON WHICH COULD ULTIMATELY SLOW ITS DEPARTURE DOWN A BIT. A MAJORITY OF THE GUIDANCE HAS US DRYING OUT FROM NORTHWEST TO SOUTHEAST BY LATE SUNDAY EVENING, JUST AHEAD OF THE BETTER LOW-LEVEL CAA KICKING IN. THERE COULD BE SOME RAIN/SNOW MIX ACROSS OUR NORTHWEST ZONES LATE IN THE PERIOD, DEPENDING ON HOW FAST WE CAN COOL BELOW 850MB AND HOW MUCH MOISTURE REMAINS. TEMPERATURES WILL BE ABOVE NORMAL ONCE AGAIN THOUGH SEVERAL DEGREES COOLER THAN TODAY WITH THE AMOUNT OF CLOUD COVER EXPECTED AND THE RAIN SHOWERS MOVING IN. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... STILL A VERY LOW CONFIDENCE FORECAST IN THE WAKE OF THE COLD FRONT FROM SUNDAY NIGHT THROUGH TUESDAY. MOST MODELS DID AGREE ON ONE THING, THEY ARE MOSTLY FOR LOCATIONS GENERALLY ALONG AND NORTH OF A PHILLY TO ACY LINE. NAM IS BY FAR THE WETTEST AND SNOWIEST OUTLIER SHOWING SNOW FOR NEARLY ALL OF THE REGION. GIVEN THAT THE TREND WITH THE OTHER MODELS HAS BEEN DRIER FOR A FEW RUNS NOW, AND GIVEN HOW MUCH OF AN OUTLIER THE NAM IS, FORECAST FAVORS THE GFS AND ECMWF. THEY BOTH SHOW THE FRONT PUSHING FURTHER SOUTH BEFORE STALLING, WITH THE FRONT NOW EXPECTED TO STALL OR SLOW BY LATE MONDAY AFTERNOON GENERALLY FROM THE FL PANHANDLE TO THE SC COAST. AS A RESULT, BUT THE TIME THE SECONDARY LOW DEEPENS AND LIFTS NE ALONG THE FRONT, IT IS MUCH FURTHER OUT TO SEA THAN WHAT PREVIOUS RUNS SHOWED. EVEN IN DELMARVA THOUGH, THIS DOESN/T APPEAR TO BE A MAJOR EVENT AS WHEN THE MOISTURE IS THE MOST ABUNDANT, SUNDAY NIGHT, IT WILL STILL BE WARM ENOUGH TO SUPPORT RAIN. BY MONDAY AFTERNOON INTO MONDAY NIGHT, COLDER AIR HAS SETTLED IN, BUT SO HAS DRY AIR ADVECTION, LIMITING MOISTURE AVAILABILITY. SO DO NOT EXPECT ANY ACCUMULATIONS ABOVE AN INCH. FOR MUCH OF THE REST OF THE WEEK, THE WEATHER LOOKS TRANQUIL, ALBEIT COLD. THE CONTINENTAL POLAR AIR MASS CONTINUES TO SETTLE IN OVER THE REGION. AS SUCH MANY LOCATIONS NORTHWEST OF THE FALL LINE WILL STRUGGLE TO GET ABOVE FREEZING FROM TUESDAY THROUGH FRIDAY. THE NEXT THING ON THE HORIZON IS AN INTENSE LOW, MODELED TO BE OVER THE SOUTHERN PLAINS BY FRIDAY LIFTING TOWARDS THE GREAT LAKES REGION. GIVEN HOW MUCH UNCERTAINTY THERE IS EARLY IN THE WEEK, AND GIVEN A LARGE SPREAD IN TIMING AND TRACK BETWEEN THE GFS AND ECMWF, IT/S RISKY TO HANG A HAT ON EITHER SOLUTION. HOWEVER, IT DOES APPEAR THAT THE IMPACTS TO THIS REGION WILL BE A CHANCE FOR PRECIPITATION, PRIMARILY WITHIN THE WARM SECTOR OF THIS LOW AS IT STAYS NW OF THE REGION (MEANING PRIMARILY RAIN). WILL HAVE A CHANCE TO REFINE THIS ONCE WE SEE HOW THE EARLY WEEK SYSTEM PLAYS OUT. && .AVIATION /05Z SUNDAY THROUGH THURSDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. 06Z TAFS CONTAIN MVFR CONDITIONS MAINLY DURING MORE FREQUENT SHOWERS DURING THE DAYTIME HOURS. EARLY MORNING, VFR SHOWERS MOVING INTO NORTHERN TERMINALS TOWARD DAWN. SOME MVFR FOG AT KILG, SHOULD DISSIPATE AS CLOUDS BECOME THICKER. OTHERWISE A VFR CIG WITH LIGHT WINDS. THIS MORNING AND AFTERNOON...NORTHERN AIRPORTS AND TERMINALS VFR SHOWERS SHOULD BE ONGOING TERMINALS WITH CIGS LOWERING TO MVFR LATER IN THE MORNING. VFR CIG IMPROVEMENT DURING THE AFTERNOON. KPHL AREA AIRPORTS AND TERMINALS/AIRPORTS TO THE SOUTH/SOUTHEAST EXPECTING A VFR CIG MORNING WITH SHOWERS OCCURRING MAINLY DURING THE AFTERNOON. MVFR CIGS ARE POSSIBLE DURING THE AFTERNOON. ALL TERMINALS VSBY RESTRICTIONS TOO BRIEF TO INCLUDE, MAINLY VFR VSBYS. WINDS WILL BECOME WEST TO NORTHWEST DURING THE LATE MORNING TO EARLY AFTERNOON AS THE COLD FRONT MOVES THROUGH. SPEEDS SHOULD BE LESS THAN 10 KNOTS. THIS EVENING. VFR MID LEVEL CIGS. NORTHWEST WINDS AVERAGING 5 TO 10 KNOTS. SOUTHERN TERMINALS AND DELMARVA AIRPORTS MIGHT SEE A SECOND SURGE OF MAINLY VFR RAIN LATE AT EVENING AND OVERNIGHT. OUTLOOK... MONDAY TO TUESDAY....MOSTLY VFR CONDITIONS EXPECTED ALONG AND NORTH OF A KACY TO KPHL LINE. FOR KMIV AND KILG, THERE IS A CHANCE FOR PRECIPITATION, SOME OF WHICH COULD FALL AS SNOW. MVFR CONDITIONS ARE POSSIBLE WITH ANY PRECIP. TUESDAY NIGHT THROUGH THURSDAY...MOSTLY VFR CONDITIONS EXPECTED ACROSS THE REGION.
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&& .MARINE... TONIGHT - SUNDAY...SUB-SCA CONDITIONS EXPECTED. SEAS WILL CONTINUE AROUND 3 FEET THROUGH LATE THIS EVENING BEFORE AN INCREASE TO AROUND 4 FEET IS POSSIBLE...BETTER FARTHER NORTH. WINDS WILL REMAIN RELATIVELY LIGHT OUT OF THE SOUTH-SOUTHWEST AROUND 10 TO MAYBE 15 KNOTS, THOUGH GUSTS SHOULD BE KEPT BELOW 20 KNOTS. WINDS BACK TOWARDS THE WEST LATER TOMORROW EVENING AS A SURFACE COLD FRONT MOVES THROUGH. OUTLOOK... MONDAY THROUGH TUESDAY...CONDITIONS SHOULD STAY BELOW SCA THRESHOLDS. HOWEVER, WAVES OF 3 TO 4 FT, AND WIND GUSTS NEAR OR JUST ABOVE 20KT WILL BE POSSIBLE ESPECIALLY LATE MONDAY NIGHT INTO TUESDAY. TUESDAY NIGHT THROUGH THURSDAY...SUB SMALL CRAFT ADVISORY CONDITIONS EXPECTED. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...JOHNSON NEAR TERM...GIGI/HEAVENER/ROBERTSON SHORT TERM...HEAVENER LONG TERM...JOHNSON AVIATION...GIGI/JOHNSON MARINE...HEAVENER/JOHNSON

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