Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 062047 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 347 PM EST FRI MAR 6 2015 .SYNOPSIS...
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ARCTIC HIGH PRESSURE SETTLES TO OUR SOUTH TONIGHT AND SATURDAY AND GRADUALLY WEAKENS. A WEAK LOW PRESSURE SYSTEM WILL THEN TRACK TO OUR NORTH SATURDAY NIGHT INTO SUNDAY, PULLING A WEAK COLD FRONT ACROSS OUR REGION. LOW PRESSURE SHOULD DEVELOP ALONG THIS FRONT TO OUR SOUTHWEST LATE MONDAY, THEN TRACK TO OUR SOUTH TUESDAY. HIGH PRESSURE SHOULD THEN BUILD INTO THE REGION WEDNESDAY THROUGH FRIDAY, HOWEVER A WEAK FRONT MAY SLIDE BY LATE WEDNESDAY.
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&& .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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HIGH PRESSURE IN PLACE WILL MOVE EAST OF THE REGION OVERNIGHT. SKIES WILL BE CLEAR WITH LIGHT WINDS UNDER 10 MPH SHIFTING FROM NORTHWEST TO WEST. THIS WILL SET-UP ANOTHER GOOD NIGHT FOR RADIATIONAL COOLING WITH A SNOWCOVER IN PLACE. TEMPERATURES SHOULD FALL OFF FAIRLY QUICKLY THIS EVENING AND INTO THE OVERNIGHT. TEMPERATURES MAY ACTUALLY RISE SOME TOWARD SUNRISE WITH THE MORE WESTERLY FLOW. OVERALL, WENT A FEW DEGREES COOLER THAN THE MAV AND MET OUTSIDE OF PHL BUT STAYED CLOSE TO THESE GUIDANCE SETS FOR OTHER ELEMENTS. SOME RECORDS ARE POSSIBLE TONIGHT ACROSS THE REGION, PLEASE SEE THE CLIMATE SECTION.
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
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A COLD FRONT WILL APPROACH THE REGION LATE IN THE DAY SATURDAY. MID TO HIGH LEVEL CLOUDS WILL BE ON THE INCREASE FROM WEST TO EAST DURING THE AFTERNOON. SOUNDINGS LOOK FAIRLY DRY ACROSS THE REGION FOR MEASURABLE PRECIPITATION. THE GFS AND RGEM INDICATE THE POTENTIAL FOR SOME NON MEASURABLE PRECIPITATION IN THE LATE AFTERNOON ACROSS THE POCONOS AND NORTHERN NEW JERSEY. HAVE ADDED SOME SCATTERED FLURRIES TO THE FORECAST IN THOSE AREAS. SOME WIND GUSTS FROM 15-20 MPH MAY BE POSSIBLE IN THE AFTERNOON AS WELL.
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&& .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
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THE OVERALL SYNOPTIC SETUP IS COMPRISED OF AN UPPER-LEVEL TROUGH FROM THE MIDWEST TO THE NORTHEAST AND MID ATLANTIC. THIS SHOULD EVENTUALLY WEAKEN AS ENERGY EJECTS ACROSS THE SOUTHERN PLAINS LATE IN THE WEEKEND AND EARLY NEXT WEEK, WITH A RIDGE BUILDING OFF THE SOUTHEASTERN U.S. COAST. THIS RESULTS IN THE UPPER-LEVEL FLOW TURNING MORE ZONAL FOR MUCH OF NEXT WEEK. THE AFOREMENTIONED ENERGY INTO THE SOUTHERN PLAINS THOUGH SHOULD RESULT IN A SURFACE LOW TRACKING TO OUR SOUTH WITH PERHAPS OVERRUNNING PRECIPITATION GETTING INTO AT LEAST A PORTION OF OUR CWA TUESDAY. WE USED A MODEL BLEND FOR SATURDAY NIGHT THROUGH MONDAY, THEN WENT WITH THE 12Z WPC GUIDANCE THEREAFTER. WE THEN MADE SOME ADJUSTMENTS AFTER ADDITIONAL COLLABORATION WITH OUR NEIGHBORING OFFICES. FOR SATURDAY NIGHT AND SUNDAY...A WEAK SHORT WAVE TRACKS TO OUR NORTH WITH A WEAK COLD FRONT MOVING THROUGH SATURDAY NIGHT. THIS FEATURE LOOKS MOISTURE STARVED WITH MUCH OF THE LIFT TO OUR NORTH AND ALSO CONFINED TO THE GREAT LAKES AREA. SOME WAA OCCURS AHEAD OF THIS FEATURE, THEN CAA ALOFT IS FORECAST TO OCCUR SUNDAY BEHIND THE WEAK COLD FRONT. WHILE THERE WILL BE SOME INCREASE IN CLOUDS, THIS LOOKS MORE PRONOUNCED ACROSS THE NORTHERN ZONES WITH EVEN THE POTENTIAL FOR SOME LOWER CLOUDS FOR A TIME. WE MAINTAINED MORE CLOUDINESS ACROSS THE NORTHERN AREAS, WITH SLIGHT CHC POPS /NORTHWEST/ FOR A FEW SNOW SHOWERS SATURDAY NIGHT /THE AIRMASS MAY REMAIN DRY OR THE FORCING WEAK ENOUGH TO NOT ALLOW PRECIPITATION TO OCCUR/. OVERALL, ANY QPF WOULD BE RATHER LIGHT. FOR MONDAY...HIGH PRESSURE AT THE SURFACE IS FORECAST TO BE OVER OUR AREA, HOWEVER A SHORT WAVE ALOFT SHOULD GENERALLY GLANCE OUR CWA. AT THE SURFACE, THIS IS REFLECTED BY A WEAK COLD FRONT THAT IS MORE PRONOUNCED TO OUR NORTH. THERE IS SOME WEAK WAA FORECAST TO OCCUR AHEAD OF THIS FEATURE, HOWEVER BASED ON THE QUICK MOTION AND ALSO LIMITED MOISTURE AVAILABLE SPELLS FOR A DRY SYSTEM SLIDING BY. WE ONCE AGAIN PLACED SOME HIGHER CLOUD COVER ACROSS THE NORTH CLOSER TO THE ACTUAL SHORT WAVE. FOR TUESDAY AND WEDNESDAY...HIGH PRESSURE SHOULD SHIFT TO OUR EAST AND SOUTHEAST AS RIDGING BUILDS OFF THE SOUTHEASTERN U.S. COAST. AS THIS OCCURS, THE FLOW BACKS SOME ALLOWING THE WAA TO INCREASE SOME THROUGH TUESDAY. THIS WILL FOCUS A WARM FRONT TO OUR NORTH WITH OUR BOUNDARY LAYER WARMING. THIS SHOULD ALLOW FOR NOTICEABLY MILDER AIR TO OVERSPREAD THE AREA WITH EACH DAY GETTING A BIT WARMER. THE STRONGER FLOW IN THE NORTHERN STREAM IS FORECAST TO SHIFT NORTHWARD, WHICH DRIVES STORMS FARTHER TO OUR NORTH. AS A RESULT, LOW PRESSURE SHOULD TRACK WELL TO OUR NORTH HELPING TO PULL WARMER AIR INTO OUR CWA. THERE SHOULD BE A FRONTAL BOUNDARY STALLED HOWEVER TO OUR SOUTH ON THE NORTHWEST EDGING OF THE BUILDING RIDGE. A SHORT WAVE SLIDING EAST ACROSS THE SOUTHERN STATES SHOULD ALLOW FOR LOW PRESSURE TO DEVELOP AND TRACK ALONG THE AFOREMENTIONED BOUNDARY. THE STRENGTH OF THE SOUTHEASTERN U.S. RIDGE MAY THEN ALLOW THIS LOW TO TRACK FARTHER NORTH AND PUSH THE OVERRUNNING PRECIPITATION SHIELD TO COVER AT LEAST A PORTION OF OUR CWA TUESDAY. WE ARE ANTICIPATING THIS TO BE RAIN IF IT WERE TO OCCUR GIVEN A MODERATING AIRMASS. WE FAVORED THE WPC POPS WHICH INCREASES THE SLIGHT CHC AND CHC POPS A BIT AND FARTHER NORTHWARD. HIGH PRESSURE BUILDS IN WEDNESDAY, ALTHOUGH A COLD FRONT MAY BE APPROACHING FROM THE NORTHWEST. FOR THURSDAY AND FRIDAY...THE WEDNESDAY FRONT SHOULD WASH OUT OR SHIFT TO OUR EAST THURSDAY. SOME RIDGING BUILDING ACROSS THE PLAINS SHOULD FORCE SURFACE HIGH PRESSURE NORTH OF THE GREAT LAKES SOUTHEASTWARD INTO THE MID ATLANTIC. THIS SHOULD BRING SOME COOLING TO THE AREA, WITH HIGHS THURSDAY ABOUT 5 DEGREES COLDER THAN WEDNESDAY. THIS HIGH SHOULD BE OVERHEAD TO START FRIDAY, THEN START TO EASE OFF TO THE EAST.
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&& .AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS EXPECTED TONIGHT AND SATURDAY. MOSTLY CLEAR TONIGHT WITH WINDS SHIFTING FROM NORTHWEST TO WEST THROUGH THE EARLY EVENING UNDER 10 KNOTS. A GENERAL INCREASE IN MID AND HIGH LEVEL CLOUDS THROUGHOUT THE DAY TOMORROW AHEAD A COLD FRONT. SOME WIND GUSTS FROM 15-20 KNOTS ARE POSSIBLE AROUND 18Z SATURDAY WITH MODERATE CONFIDENCE FOR THESE GUSTS. OUTLOOK... SATURDAY NIGHT AND SUNDAY...SOME MVFR CEILINGS POSSIBLE ESPECIALLY FROM ABOUT KTTN TO KABE NORTHWARD. OTHERWISE, VFR WITH SOME INCREASE IN CLOUDS FOR A TIME. MONDAY...VFR OVERALL. TUESDAY AND WEDNESDAY...VFR, HOWEVER A PERIOD OF MVFR/IFR CONDITIONS POSSIBLE ESPECIALLY FROM ABOUT THE KPHL METRO ON SOUTHWARD TUESDAY WITH A CHANCE OF SOME RAIN.
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&& .MARINE...
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SEAS WILL CONTINUE TO DECREASE TO AROUND 2-3 FEET FOR TONIGHT ON THE OCEAN WITH LOWER SEAS CLOSER TO 1-2 FEET ON THE BAY. NORTHWEST WINDS WILL SHIFT TO WEST THIS EVENING WITH TOP GUSTS SATURDAY AFTERNOON FROM 15-20 KNOTS. OUTLOOK... SATURDAY NIGHT AND SUNDAY...A WEST-SOUTHWEST FLOW INCREASES SOME FOR A TIME AS A WEAK FRONT ARRIVES, HOWEVER OVERALL THE CONDITIONS SHOULD BE BELOW SMALL CRAFT ADVISORY CRITERIA. MONDAY...OVERALL, CONDITIONS BELOW SMALL CRAFT ADVISORY CRITERIA AS HIGH PRESSURE MOVES ACROSS THE AREA. TUESDAY AND WEDNESDAY...LOW PRESSURE IS FORECAST TO TRACK TO OUR SOUTH, HOWEVER IF IT FAVORS A MORE NORTHWARD TRACK THEN WINDS MAY INCREASE ENOUGH TO ADVISORY LEVELS FOR A TIME MAINLY TUESDAY.
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&& .CLIMATE...
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FOR REFERENCE, BELOW ARE THE RECORD LOW TEMPERATURES FOR SATURDAY, MARCH 7TH. ACY...10 IN 1890 PHL....9 IN 1960 ILG...11 IN 1960 ABE....1 IN 1960 TTN....7 IN 1890 GED....3 IN 1960 RDG...10 IN 1989 MPO..-18 IN 1911
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...GORSE NEAR TERM...GAINES SHORT TERM...GAINES LONG TERM...GORSE AVIATION...GAINES/GORSE MARINE...GAINES/GORSE CLIMATE...

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