Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 221640 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1140 AM EST SAT NOV 22 2014 .SYNOPSIS... STRONG HIGH PRESSURE OVER THE MID ATLANTIC REGION WILL GRADUALLY SHIFT OFFSHORE THROUGH TONIGHT. LOW PRESSURE DEVELOPING OVER THE SOUTHERN PLAINS WILL MOVE NORTHEASTWARD SUNDAY, PULLING A WARM FRONT THROUGH OUR REGION SUNDAY NIGHT INTO MONDAY. THE LOW WILL BE NEAR THE GREAT LAKES TOWARD MONDAY MORNING, AND AS IT MOVES INTO EASTERN CANADA BY TUESDAY ITS ASSOCIATED COLD FRONT WILL CROSS OUR AREA. HIGH PRESSURE WILL BUILD IN MONDAY NIGHT AND TUESDAY, THEN AN AREA OF LOW PRESSURE MAY DEVELOP OFF THE MID ATLANTIC COAST WEDNESDAY INTO THURSDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A 1035 MB SURFACE HIGH PRESSURE SYSTEM CENTERED OVER EASTERN NORTH CAROLINA WILL SLOWLY SHIFT EASTWARD THROUGH THIS AFTERNOON. THE WATER VAPOR IMAGERY SHOWS A SHORT WAVE FROM THE EASTERN GREAT LAKES TO THE UPPER OHIO VALLEY LIFTING NORTHEASTWARD. SOME INCREASE IN THE WAA IS OCCURRING TODAY ESPECIALLY ALOFT, AND THIS IS EVIDENT IN THE 12Z STERLING, VA RAOB WITH A WARM LAYER CENTERED JUST ABOVE 900 MB. THE WAA AND SOME ISENTROPIC LIFT IS FORECAST TO OCCUR, WITH THIS BEST NOTED NEAR OUR FAR NORTHWEST ZONES LATER THIS AFTERNOON. SOME GUIDANCE HAS BEEN TRYING TO BRING SOME LIGHT QPF INTO PORTIONS OF THE POCONOS LATE THIS AFTERNOON. THE FORECAST SOUNDINGS SHOW THAT WITH THE WAA, THE PRECIPITATION TYPE WOULD BE EITHER RAIN, FREEZING RAIN OR PERHAPS A FEW ICE PELLETS. THESE SOUNDINGS ALSO SHOW A PRONOUNCED DRY LAYER IN THE LOWEST LEVELS, WHICH COULD ALSO SUGGEST THAT IT COULD BE VIRGA. THE SREF PROBABILITIES FOR FREEZING RAIN HAVE BASICALLY BEEN 30 PERCENT OR LESS FOR A TIME FOR PORTIONS OF THE POCONOS CENTERED AROUND 00Z. THIS IS LOW AND AND IT APPEARS LITTLE IF ANY PRECIPITATION REACHES THE GROUND. THEREFORE, WE WENT WITH A DRY FORECAST DURING THE DAYTIME HOURS. OTHERWISE, SOME CLOUDS WILL INCREASE BY LATER THIS AFTERNOON ESPECIALLY ACROSS THE WESTERN ZONES CLOSER TO THE SHORT WAVE, WAA AND LOW-LEVEL JET PUSH. AS THE BOUNDARY LAYER WARMS, BETTER MIXING IS OCCURRING AND THEREFORE SOME GUSTINESS IN THE WINDS CAN BE EXPECTED BEFORE THESE DROP OFF TOWARD EVENING. THE HOURLY TEMPERATURES WERE ADJUSTED BASED ON THE LATEST OBSERVATIONS, THEN THE LAMP/LAV GUIDANCE WAS BLENDED IN. NO MAJOR CHANGES WERE MADE TO THE HIGH TEMPERATURES ATTM. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/... A MID LEVEL SHORT WAVE TROUGH MOVES OVER THE NORTHEASTERN U.S., AND BOTH THE GFS AND NAM SHOW THE BEST SYNOPTIC LIFT (AS EVIDENCED BY 500 MB Q VECTOR CONVERGENCE AND POSITIVE PRESSURE ADVECTION ON THE 1.5 PV SURFACE) STAYING JUST NORTH OF OUR REGION. HOWEVER, GIVEN HOW CLOSE THE LIFT IS, AND GIVEN THAT THERE COULD ALSO BE SOME OROGRAPHIC LIFT, HAVE SOME LOW POPS ACROSS THE NORTHWEST ZONES FOR A TIME. BUT IT STILL SEEMS LIKE AN UNLIKELY EVENT FOR OUR REGION, SO MOST OF THAT REGION HAS POPS AT OR BELOW 30 PERCENT. IF THERE IS ANY PRECIPITATION IN OUR AREA, IT WILL BE EITHER IN THE FORM OF RAIN OR FREEZING RAIN (DEPENDING ON SURFACE TEMPERATURE). MODEL SOUNDINGS SHOW A ROBUST AND DEEP WARM LAYER. WHILE THERE COULD BE SOME SEEDER FEEDER CIRRUS CLOUDS PROPAGATING OVERHEAD, WITH THE MELTING LAYER AROUND 8000 FT MSL, ANY ICE CRYSTALS WOULD MELT THROUGH THE WARM LAYER. BECAUSE OF THE CONTINUED WARM AIR ADVECTION EVEN AT THE SURFACE, SEE VERY FEW LOCATIONS DROPPING BELOW FREEZING BEFORE THE WINDOW OF OPPORTUNITY FOR PRECIPITATION CLOSES. SINCE TOO, THE CHANCE OF PRECIPITATION IS VERY SMALL AT THIS TIME, WILL NOT ISSUE A FREEZING RAIN ADVISORY, BUT WILL CONTINUE TO MENTION THE POTENTIAL IN THE HWO. && .LONG TERM /SUNDAY THROUGH FRIDAY/... A NICE WARMING TREND IS IN STORE AT THE START OF THE EXTENDED PD AS HIGH PRES MOVES OFFSHORE AND STRONG SWLY FLOW DEVELOPS OVER THE AREA. THEN, LOW PRES WILL TAKE SHAPE OVER THE SRN PLAINS AND BEGIN TO MOVE NEWD. THE WMFNT ASSOCD WITH THIS LOW WILL MOVE THRU THE REGION SUN NIGHT AS THE LOW REALLY INTENSIFIES OVER THE MIDSECTION OF THE NATION. BASED ON THE LATEST GUID MOVG THE PRECIP IN SLOWER, HAVE REMOVED POPS FROM THE SUNDAY DAYTIME HOURS. THE BEST WAA IS SUN NIGHT AND THIS IS THE WETTEST PERIOD WITH RAIN, SOME HEAVY AT TIMES. WE GET DRY SLOTTED LATER MON AND IN THE WARM SECTOR, TEMPS WILL SKYROCKET AND COULD REACH RECORD VALUES IN SOME LOCATIONS, THEN THE COLD FRONT WILL CROSS THE REGION MONDAY NIGHT, WITH ANOTHER CHC OF PRECIP MON EVE BEFORE HIGH PRES BUILD BACK IN FOR LATER MON NIGHT THRU TUE NIGHT. THEN, ALL EYES TURN TO THE POTENTIAL FOR A COASTAL LOW DEVELOPING AROUND WED. MODEL SOLNS ARE ALL OVER THE PLACE AND CONFIDENCE IS MUCH BELOW AVERAGE ATTM. THE CMC IS WELL OFFSHORE WITH VIRTUALLY NO IMPACT TO OUR REGION. THE GFS INDICATES THE MOST IMPACT FOR OUR SRN AND ERN LOCATIONS WED INTO WED NIGHT BEFORE THE LOW PULLS AWAY ON THANKSGIVING, BRINGING A DRY HOLIDAY. THE ECMWF HAS THE STRONGEST AND MOST WWD SOLN AND WOULD BRING A MOSTLY WET AND WINDY PERIOD FROM WED INTO WED NIGHT. IT HAS SOME SUPPORT FROM THE UKMET. ANY WINTRY PRECIP WOULD BE CONFINED TO NRN AND WRN AREAS AT THE ONSET AND THE END. WITH THE POTENTIAL FOR SIGNIFICANT IMPACT DUE TO HOLIDAY TRAVEL AND ONE OF THE BUSIEST AIR TRAVEL DAYS OF THE YEAR, THIS SYS WILL CONTINUE TO BE WATCHED AND COULD END UP BEING NOTHING OR SOMETHING SIGNIFICANT. THE ECMWF MADE A DECENT WWD SHIFT FROM 21/12Z TO 22/00Z, THE GFS DID NOT. AFTER THIS STORM MOVES BY WHETHER FAR OFFSHORE OR CLOSE TO THE COAST, ANOTHER WK CDFNT MAY BRING SOME PRECIP ERLY FRI. TEMPS WILL START OFF FAIRLY WARM ON SUNDAY, REACH THEIR ZENITH ON MON, WITH NEAR RECORD WARMTH, THEN STILL BE NR NRML ON TUE BEFORE TAKING A NOSE DIVE THRU THE REMAINDER OF THE WEEK. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THIS AFTERNOON...VFR, WITH SOME INCREASE IN CLOUDS ESPECIALLY FOR THE KABE AND KRDG AREAS. SOUTHWESTERLY WINDS AROUND 10 KNOTS WITH SOME GUSTS TO AROUND 20 KNOTS. TONIGHT...VFR, WITH AREAS OF CEILINGS AT OR ABOVE 5,000 FEET. SOUTHWESTERLY WINDS DIMINISHING TO 5 KNOTS OR LESS. SUNDAY...VFR, WITH CEILINGS AT TIMES ABOVE 5,000 FEET. SOUTHWEST WINDS 5-8 KNOTS, BECOMING SOUTHEAST LATE. OUTLOOK... SUN NIGHT THROUGH EARLY MON...VERY POOR FLYING CONDS WITH MVFR EXPECTED AND IFR PSBL IF NOT PROBABLE IN RAIN. RAIN COULD BE HVY AT TIMES. E TO SE WIND COULD GUST IN THE 20 TO 25 KT RANGE. MDT TO HIGH CONFIDENCE. MON AND MON NIGHT...IMPROVING CONDS BUT STILL SOME MVFR PSBL IN LINGERING SHWRS. CFP/WSFHT MON EVE. VFR BY EVE IF NOT SOONER. LOW TO MDT CONFIDENCE. WEDNESDAY...MUCH UNCERTAINTY DEPENDING ON THE TRACK OF A COASTAL LOW. COULD BE VFR IF LOW IS FAR ENOUGH EAST OR MVFR/IFR IN RAIN AND WIND IF LOW IS FAR ENOUGH W. BEST CHC FOR VFR IS WRN AIRPORTS. BEST CHC FOR DEGRADED CONDS IS ERN AIRPORTS. CONFIDENCE VERY LOW. && .MARINE... THE SOUTHWESTERLY FLOW ON THE BACKSIDE OF HIGH PRESSURE WILL INCREASE SOME THROUGH THIS AFTERNOON. SOME GUSTS TO 25 KNOTS SHOULD OCCUR ESPECIALLY ACROSS THE NORTHERN WATERS, HOWEVER IT MAY BE GENERALLY MARGINAL. THERE SHOULD BE A BETTER CHC OF GUSTS TO AROUND 25 KNOTS TONIGHT ACROSS THE COASTAL WATERS AS THE PRESSURE GRADIENT TIGHTENS SOME. WAVE HEIGHTS SHOULD RESPOND THROUGH TONIGHT AND BUILD UP TO 5 FEET IN THE ATLANTIC, AND MAY BE SLOWER TO DECREASE SUNDAY MORNING. FOR NOW, A SMALL CRAFT ADVISORY IS IN EFFECT THROUGH 6 AM SUNDAY MORNING FOR ALL BUT THE DELAWARE BAY. OUTLOOK... SUN...NO MARINE HEADLINES ANTICIPATED. SUN NIGHT THROUGH MON...SCA CONDS ARE EXPECTED AND GALES ARE PSBL IF NOT PROBABLE INTO ERLY MON AS STRONG LOW PRES IMPACTS THE WATERS. MON NIGHT INTO TUE....BACK END SCA CONDS AS SEAS AND WIND SUBSIDE SLOWLY. WED...NO MARINE HEADLINES ANTICIPATED. && .CLIMATE... FOR OUR EIGHT CLIMATE SITES, HERE ARE THE RECORD HIGH TEMPERATURES FOR NOVEMBER 24TH AND THE MOST RECENT YEAR OF OCCURRENCE. RECORD HIGHS 11/24: ACY: 72 SET IN 1999 PHL: 71 SET IN 1979 ILG: 73 SET IN 1979 ABE: 69 SET IN 1931 TTN: 71 SET IN 1979 GED: 75 SET IN 1992 RDG: 69 SET IN 1979 MPO: 64 SET IN 1931 && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST SUNDAY FOR ANZ450>455. && $$ SYNOPSIS...GORSE/NIERENBERG NEAR TERM...GORSE SHORT TERM...JOHNSON LONG TERM...NIERENBERG AVIATION...GORSE/NIERENBERG MARINE...GORSE/JOHNSON/NIERENBERG CLIMATE...DRAG/KLINE

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