Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 020653 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 253 AM EDT THU APR 2 2015 .SYNOPSIS...
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HIGH PRESSURE WILL SHIFT OFFSHORE THIS MORNING. A WARM FRONT WILL LIFT ACROSS THE AREA THIS AFTERNOON. A COLD FRONT WILL APPROACH THE AREA FRIDAY, WHILE AN AREA OF LOW PRESSURE DEVELOPS ALONG THE FRONT ACROSS THE SOUTHERN PLAINS AND MOVES ACROSS THE AREA FRIDAY NIGHT INTO SATURDAY MORNING. HIGH PRESSURE WILL BUILD TO OUR SOUTH SUNDAY, WHILE A COLD FRONT SAGS SOUTHWARD ACROSS THE AREA. THIS FRONT MAY STALL NEAR THE AREA THROUGH THE MIDDLE OF NEXT WEEK, WITH SEVERAL WAVES OF LOW PRESSURE MOVING ALONG THE BOUNDARY.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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CLEAR BEAUTIFUL EARLY MORNING WITH IDEAL RADIATING CONDITIONS MUCH OF THE COUNTRYSIDE WHERE IT SHOULD BE A BIT FROSTY. MOST OF THE SNOW IS MELTED EXCEPT IN THE SHADED REGIONS N OF I-80. A SUNNY MILD DAY FOLLOWS WITH BREEZY SOUTHWEST WIND GUSTS NEAR 30 MPH THIS AFTERNOON AND A BIT OF HIGH CLOUDINESS. AFTERNOON TEMPS 4 TO 8 DEGREES ABOVE NORMAL...NEAR 65 EXCEPT COOLER IN THE ELEVATIONS ABOVE 500 FEET. USED PRIOR 330 PM WEDNESDAY FCST TEMPS AS THE BASIS OF THIS FCST AS THEY LOOK BETTER THAN THE COOLER MET/MAV GUIDANCE. THE ECMWF 2M TEMPS CONTINUE TO SUPPORT THE WARMER FCST IN A STRONG DRY WAA PATTERN.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
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BECOMING CLOUDY. SPRINKLES POSSIBLE THIS EVENING E PA AND NNJ AND STEADIER SHOWERS POSSIBLE TOWARD DAWN FRIDAY AS A COLD FRONT APPROACHES FROM THE NW ALONG WITH ITS ASSOCIATED MODEST INSTABILITY BURST. KI NEAR 32. SLIGHT CHC OF A TSTM E PA AND NJ LATE AS THE ECMWF IS SLIGHTLY MORE UNSTABLE WITH ITS ELEVATED INSTABILITY AS SEEN VIA THE SWI. THUNDER IS NOT IN THE GRIDS ATTM DUE TO ITS LOW PROB OF OCCURRENCE. LOWS 10 TO 15 DEGREES ABOVE NORMAL. USED THE WARMER 00Z/2 GFS MAVMOS.
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&& .LONG TERM /FRIDAY THROUGH WEDNESDAY/... A COLD FRONT APPROACHES THE AREA LATE THURSDAY NIGHT, SETTING UP THE BEGINNING OF A WET PERIOD THROUGH FRIDAY NIGHT. THE FRONT DOES NOT LOOK TO MAKE IT FULLY INTO OUR AREA THROUGH FRIDAY AS IT MAY STALL JUST TO OUR NORTH, WHILE AN AREA OF LOW PRESSURE DEVELOPS ALONG THE FRONT ACROSS THE SOUTHERN PLAINS. THIS LOW IS FORECAST TO MOVE ALONG THE BOUNDARY DURING THE DAY FRIDAY, AND MOVE ACROSS THE AREA FRIDAY NIGHT, FINALLY PULLING THE COLD FRONT THROUGH THE AREA OVERNIGHT INTO EARLY SATURDAY MORNING. SEVERAL VORTICITY IMPULSES WILL BE TRAVERSING THE AREA DURING THIS TIME PERIOD, WHICH WILL LEAD TO SEVERAL PERIODS OF SHOWER ACTIVITY THROUGH FRIDAY NIGHT. THERE REMAINS SOME WEAK INSTABILITY FORECAST ACROSS THE REGION FRIDAY INTO FRIDAY EVENING AS A PORTION OF THE AREA WILL LIKELY BE IN THE WARM SECTOR OF THE SYSTEM, SO WE WILL KEEP A MENTION OF THUNDERSTORMS IN THE FORECAST. DUE TO THE LACK OF STRONG INSTABILITY AND STEEP MID-LEVEL LAPSE RATES, WE ARE NOT EXPECTING SEVERE WEATHER. HOWEVER, IF THUNDERSTORMS DO OCCUR, THEY COULD PRODUCE SOME STRONG GUSTY WINDS. ACTUALLY, IT IS POSSIBLE THAT FRIDAY MAY BE A GUSTY DAY IN GENERAL DUE TO THE SYNOPTIC PRESSURE GRADIENT. AS THE FRONT MOVES ACROSS THE AREA FRIDAY NIGHT, IT IS POSSIBLE THAT ENOUGH COLD AIR COULD MOVE INTO THE AREA TO CHANGE THE RAIN OVER TO SNOW FOR A PERIOD ACROSS THE POCONOS. THE COLD FRONT IS EXPECTED TO HAVE MOVED PAST THE AREA BY SATURDAY MORNING. THERE COULD BE A FEW LINGERING SHOWERS EARLY IN THE DAY, BUT WE EXPECT ANY PRECIPITATION TO END THROUGH THE MORNING HOURS. AS THE LOW MOVES WELL TO OUR NORTH, STRONG NORTHWEST FLOW WILL DEVELOP ACROSS THE AREA, LEADING TO A GUSTY DAY. DRY WEATHER IS EXPECTED TO CONTINUE INTO SATURDAY NIGHT AS HIGH PRESSURE BUILDS TO OUR SOUTH. THE STRONG WIND GUSTS SHOULD BEGIN TO DROP OFF OVERNIGHT. ON SUNDAY, A COLD FRONT WILL APPROACH THE AREA FRONT THE NORTH, BUT MAY NOT FULLY MAKE IT ACROSS THE AREA AS THE FRONT MAY STALL JUST TO THE NORTH. AN AREA OF LOW PRESSURE IS FORECAST TO MOVE ALONG THE BOUNDARY LATE SUNDAY INTO SUNDAY NIGHT, THEN LIFT TO OUR NORTHEAST EARLY MONDAY WHEN THE FRONT MAY FINALLY PUSH ACROSS THE AREA. HOWEVER, THIS IS WHEN THERE ARE DIFFERENCES WITH THE LONG TERM MODELS. THE GFS ENDS UP LIFTING THIS FRONT BACK NORTHWARD MONDAY NIGHT INTO TUESDAY, BEFORE PROGRESSIVELY MOVING AN AREA OF LOW PRESSURE OUT OF THE MID-WEST AND ACROSS THE NORTHEAST TUESDAY THROUGH WEDNESDAY. THE ECMWF STALLS THE FRONT ACROSS OUR AREA FOR MONDAY THROUGH AT LEAST WEDNESDAY, BEFORE SLOWLY MOVING AN AREA OF LOW PRESSURE ACROSS THE AREA LATE WEDNESDAY INTO WEDNESDAY NIGHT. WITH THE DIFFERENCE IN MODEL GUIDANCE AND THE FACT ITS STILL PRETTY FAR OUT, WE`VE STAYED CLOSE TO WPC GUIDANCE WHICH MORE CLOSELY RESEMBLES THE ECMWF AND ENSEMBLES. THAT BEING SAID, THE EARLY TO MID PART OF NEXT WEEK COULD BE UNSETTLED. && .AVIATION /07Z THURSDAY THROUGH MONDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THROUGH 12Z...CLEAR WITH A FEW CIRRUS MOVING SEWD. CALM TO LIGHT SSW WIND. AFTER 12Z TODAY...VFR CLEAR OR SCT CLOUDS AOA 20000 FT. SW WIND INCREASING WITH GUSTS DURING THE AFTERNOON OF 25-30 KT. TONIGHT...CIGS AOA 6000 FT AFTER 22Z TODAY BECOMING MVFR OR IFR IN SHOWERS AFTER 10Z VCNTY KRDG/KABE BUT PROBABLY REMAINING VFR PHL SOUTHWARD. MODEST LOW LEVEL WIND SHEAR. SW SFC WIND 10-15 KT WITH WINDS AT 1000 FT 210 DEGREES 35-40 KT MUCH OF THE NIGHT AND 230 DEGREES 50 KT AT 2000 FT, ESPECIALLY NEAR 05Z/3. OUTLOOK... FRIDAY-FRIDAY NIGHT...PERIODS OF MVFR AND IFR CONDITIONS WITH SHOWERS LIKELY; THUNDERSTORMS POSSIBLE FRIDAY. GUSTY SOUTHWEST WINDS 20-30 KNOTS FRIDAY. SATURDAY-MONDAY...MOSTLY VFR. GUSTY WEST-NORTHWEST WINDS 20-30 KNOTS DURING THE DAY SATURDAY AND SUNDAY.
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&& .MARINE...
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NO HEADLINES PRIOR TO NOON AS THE WINDS TURN S-SW AT 10-15 KT. SCA THIS AFTN-TONIGHT AS THE SW WIND GUSTS NEAR 25 KT, ESPECIALLY NEAR SHORE THIS AFTN. OUTLOOK... FRIDAY-SATURDAY NIGHT...AN EXTENDED PERIOD OF SMALL CRAFT ADVISORY CONDITIONS POSSIBLE AS A COLD FRONT AND LOW PRESSURE SYSTEM AFFECT THE AREA AND MOVE THROUGH. SUNDAY-MONDAY...WINDS MAY APPROACH ADVISORY LEVELS SUNDAY THROUGH MONDAY.
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&& .FIRE WEATHER...
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WE ARE FORECASTING A SOUTH TO SOUTHWEST WIND INCREASING TO 15 TO 20 MPH THIS AFTERNOON. THERE WILL BE GUSTS OF 25 TO 30 MPH AT THAT TIME. ALSO, RELATIVE HUMIDITY VALUES ARE EXPECTED TO DROP TO AROUND 25 PERCENT AND FUEL MOISTURE LEVELS WILL BE ON THE DECREASE. THERE WILL BE AN ENHANCED THREAT OF RAPID WILDFIRE SPREAD THIS AFTERNOON, EXCEPT FOR THOSE AREAS THAT STILL HAVE ANY SNOW COVER(N OF I-80) . WE WILL BE ISSUING A SPECIAL WEATHER STATEMENT AT ABOUT 4 AM FOR ENHANCED FIRE DANGER THIS AFTERNOON. WE WILL CONTINUE TO MONITOR THE SITUATION WITH OUR PARTNERS FOR ANY FURTHER UPGRADES.
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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 2 PM THIS AFTERNOON TO 6 AM EDT FRIDAY FOR ANZ430-431-450>455.
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&& $$ SYNOPSIS...ROBERTSON NEAR TERM...DRAG 253 SHORT TERM...DRAG 253 LONG TERM...ROBERTSON AVIATION...DRAG/ROBERTSON 253 MARINE...DRAG/ROBERTSON 253 FIRE WEATHER...253

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