Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 231433 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 933 AM EST SUN NOV 23 2014 .SYNOPSIS...
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LOW PRESSURE WILL LIFT FROM THE SOUTHERN PLAINS TO THE EASTERN GREAT LAKES REGION TODAY INTO MONDAY. AS IT DOES, A WARM FRONT WILL LIFT THROUGH OUR REGION TONIGHT, THEN A COLD FRONT WILL SWEEP THROUGH LATE MONDAY. HIGH PRESSURE FOLLOWS FOR LATER TUESDAY. A COASTAL STORM WILL DEVELOP OFF THE CAROLINA COAST WEDNESDAY BEFORE MOVING EAST OF NEW ENGLAND BY THANKSGIVING. A SECOND COLD FRONT WILL MOVE THROUGH LATE THURSDAY, THEN HIGH PRESSURE BUILDS IN LATER FRIDAY INTO SATURDAY.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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HIGH PRESSURE CENTERED EAST OF THE MID ATLANTIC COAST IS RESULTING IN A RETURN FLOW ACROSS THE ENTIRE AREA. AN UPPER-LEVEL TROUGH CONTINUES TO AMPLIFY FROM THE NORTHERN PLAINS TO THE LOWER MISSISSIPPI VALLEY, WITH A STRONG SHORT WAVE EVIDENT ON THE WATER VAPOR IMAGERY OVER LOUISIANA. DOWNSTREAM FROM THIS, A RIDGE IS BUILDING ACROSS THE EAST. THE PRESENT OF THIS RIDGE IS HELPING TO DEFLECT LINGERING WEAK LIFT FARTHER NORTHWARD. THIS IS ALSO WHERE THE LOW-LEVEL JET IS SHIFTING WITH TIME TODAY. THEREFORE, ANY SPRINKLES ACROSS THE FAR NORTH ARE EXPECTED TO END. THERE ARE TWO BANDS OF MORE PRONOUNCED CLOUDINESS, ONE ACROSS THE NORTH WITH THE AFOREMENTIONED WEAK LIFT, AND THE SECOND IS ACROSS PORTIONS OF OUR DELMARVA ZONES. THE LATTER IS CIRRUS FROM THE DEVELOPING SYSTEM ACROSS THE GULF COAST STATES. OVERALL, CLOUDS WILL MIX WITH SUNSHINE TODAY HOWEVER THERE IS EXPECTED TO BE MORE OF AN INCREASE ESPECIALLY FROM SOUTH TO NORTH BY EVENING. GIVEN THE WAA OCCURRING WITHIN A SOUTHERLY FLOW REGIME PLUS TEMPERATURES STARTING MUCH WARMER THAN 24 HOURS AGO, HIGHS WILL BE IN THE 50S FOR MANY AREAS THIS AFTERNOON. NO MAJOR CHANGES WERE MADE TO THE HIGH TEMPERATURES, AND THE HOURLY GRIDS WERE ADJUSTED BASED ON THE LATEST OBSERVATIONS. THIS INCLUDED A FASTER INCREASE IN THE TEMPERATURES SO FAR THIS MORNING FOR SEVERAL AREAS.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... THE AFOREMENTIONED LOW WILL MOVE TOWARD THE GRTLKS TONIGHT AND BRING ITS ASSOCD WMFNT THRU ERLY AND A MARKED INCREASE IN SWLY FLOW. THERE WILL ALSO BE AN INCREASE IN MOISTURE AND THE DEVELOPMENT OF A POTENT LLJ. OVERNIGHT LOWS TONIGHT WILL NOT DROP MUCH IN RESPONSE TO THICKENING AND LOWERING CLOUDS AND THE SWLY WIND. PRECIP CHCS WILL INCREASE THRU THE NIGHT. DURG THE EVE THE BEST CHCS WILL BE S AND W WITH PRECIP EVERYWHERE AND HIGH POPS DURG THE OVERNIGHT AND ERLY MRNG HOURS. RAIN COULD BE HVY AT TIMES AND SOME THUNDER CAN NOT BE RULED OUT ESPECIALLY S AND E. QPF VALUES WILL GENLY BE BETWEEN 1/2 AND 3/4 OF AN INCH WITH LOCALLY HIGHER AMOUNTS. WITH TEMPS EXPECTED TO BE WELL ABOVE FREEZING EVERYWHERE ALL OF THE PRECIP THAT FALLS WILL BE IN THE LIQUID FORM. && .LONG TERM /MONDAY THROUGH SATURDAY/...
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BIG STORY IS THE WEDNESDAY COASTAL SYSTEM...BUT BEFORE WE GET AHEAD OF OURSELVES, THERE ARE A FEW THINGS TO TALK ABOUT FOR MONDAY. HARD TO BELIEVE WE COULD GO FROM A RECORD LOW AT ALLENTOWN YESTERDAY TO NEAR RECORD HIGHS JUST TWO DAYS LATER, BUT THAT IS WHAT IS LOOKING LIKE IN THE WAKE OF THE WARM FRONT. AS MENTIONED IN THE SHORT TERM SECTION, THERE IS A HIGH CHANCE OF RAIN EARLY IN THE DAY. ALSO, AFTER SUNRISE, THERE LOOKS TO BE SOME ELEVATED INSTABILITY ABOVE THE STABLE MARINE LAYER ESPECIALLY NEAR THE COASTS IN DE AND SOUTHERN NJ. THUS, CONTINUE WITH MENTION OF THUNDER. RAIN SHOULD MOVE OUT BY THE LATE AFTERNOON/EARLY EVENING HOURS, WELL AHEAD OF THE ARRIVAL OF THE COLD FRONT. THERE IS GOOD MODEL AGREEMENT ON THE TIMING OF THE COLD FRONT...MOVING THROUGH THE REGION DURING THE OVERNIGHT HOURS MONDAY NIGHT. THEN TUESDAY LOOKS LIKE A PLEASANT DAY. TEMPERATURES WILL BE 15 TO 20 DEGREES LOWER AS COMPARED TO MONDAY, BUT NEAR NORMALS. WEDNESDAY AND WEDNESDAY NIGHT...THE PERIOD EVERYONE IS TALKING ABOUT. STILL LOOKING AT A COASTAL SYSTEM DEVELOPING OFF THE CAROLINA COAST EARLY ON WEDNESDAY THEN LIFTING NORTHEAST, AND WILL BE EAST OF NEW ENGLAND BY THURSDAY. THERE ARE STILL SOME MODEL DIFFERENCES MOST NOTABLY WITH THE TRACK OF THE SURFACE LOW, THOUGH THE GAP IS CLOSING BETWEEN THE ECMWF TRACK (STILL THE FURTHEST WEST) AND THE CMC TRACK (STILL THE FURTHEST EAST), WITH THE GFS IN A COMFORTABLE MIDDLE GROUND. AS FAR AS PRECIP CHANCES, IT LOOKS VERY LIKELY THAT AREAS EAST AND SOUTH OF THE I95 CORRIDOR WILL SEE PRECIPITATION DURING THE DAY WEDNESDAY INTO WEDNESDAY EVENING. FOR AREAS NORTH AND WEST OF THE I95 CORRIDOR, THE CHANCE IS LESS, THOUGH STILL QUITE HIGH THAT THERE WILL BE WIDESPREAD PRECIP THROUGH WEDNESDAY NIGHT AS EVEN THE MIDDLE OF THE ROAD GFS SOLUTION SHOWS THE PRECIP EXTENDING WEST OF THE POCONOS. PRECIP TYPE IS CONSIDERABLY MORE UNCERTAIN. THE ECMWF DEPICTS A MID LEVEL SOUTHWESTERLY JET OVER THE EASTERN HALF OF THE REGION, PRODUCING A ROBUST WARM LAYER WHICH WOULD MEAN VERY FEW ICE CRYSTALS ALOFT. HOWEVER, WITH THE EXCEPTION OF THE HIGHER TERRAIN OF THE POCONOS, THE ECMWF KEEPS SURFACE TEMPERATURES WELL ABOVE FREEZING, SO JUST A COLD RAIN FOR MOST OF THE REGION WHILE THERE IS A SLIM CHANCE OF FREEZING PRECIP IN THE HIGHER TERRAIN OF THE POCONOS. THE GFS ON THE OTHER HAND, HAS THE JET, AND CONSEQUENTLY MID LEVEL WARM AIR ADVECTION OVER THE OCEAN, RESULTING IN EITHER ALL RAIN OR A RAIN/SNOW MIX FOR MOST OF THE AREA, WITH ALL SNOW POSSIBLE IN THE POCONOS. WITH EITHER SOLUTION, THE CHANCES OF SIGNIFICANT ACCUMULATING SNOW DURING THE DAY SEEM SMALL (WITH THE EXCEPTION OF THE POCONOS). WHAT COULD BE THE BIGGER ISSUE IS IF OR HOW LONG THE PRECIP LINGERS THROUGH THE NIGHT TIME HOURS WEDNESDAY NIGHT. THE GFS HAS PRECIP RAPIDLY MOVING OUT BY MIDNIGHT WEDNESDAY NIGHT. WITH THIS SOLUTION, WHILE MUCH OF THE REGION COULD SEE A PERIOD OF ALL SNOW AFTER SUNSET, THE WINDOW OF OPPORTUNITY FOR ACCUMULATING SNOW WOULD BE BRIEF. THE ECMWF ON THE OTHER HAND, LINGERS PRECIP IN THE REGION THROUGH THURSDAY MORNING, BUT KEEPS THE EASTERN HALF THE REGION ABOVE FREEZING THROUGH THE NIGHT. ALL THAT TO SAY THAT WHILE PRECIPITATION LOOKS VERY LIKELY IN THE WEDNESDAY TO WEDNESDAY NIGHT PERIOD, THE CHANCE FOR SIGNIFICANT ACCUMULATING SNOW FOR MOST OF THE REGION IS QUITE SMALL. ONCE THE PRECIP CLEARS OUT, THANKSGIVING LOOKS TO BE PLEASANT, ALBEIT CHILLY WITH HIGHS ABOUT 10 DEGREES BELOW NORMAL. IN THE WAKE OF THE COASTAL LOW, A CONTINENTAL POLAR AIR MASS SETTLES IN OVER THE REGION FOR THE REMAINDER OF THE WEEK KEEPING HIGHS IN THE 30S AND 40S.
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&& .AVIATION /15Z SUNDAY THROUGH THURSDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. REST OF TODAY...VFR, WITH CEILINGS MAINLY AT OR ABOVE 10,000 FEET. SOUTHWESTERLY WINDS 10 KNOTS OR LESS, BECOMING SOUTHEASTERLY TOWARD EVENING. TONIGHT...VFR TO START, THEN CEILINGS ARE EXPECTED TO QUICKLY LOWER TO MVFR AND IFR /LOCAL LIFR/ AS A WARM FRONT ARRIVES. A PERIOD OF RAIN IS EXPECTED TO MOVE THROUGH, SOME OF WHICH COULD BE HEAVY AT TIMES. THIS WILL ALSO REDUCE THE VISIBILITIES, WITH EVEN SOME FOG POSSIBLE LATE ESPECIALLY TOWARD THE COAST AND FROM NEAR KABE ON NORTHWARD. SOUTH TO SOUTHEAST WINDS AT 5-10 KNOTS WILL INCREASE TO NEAR 15 KNOTS OVERNIGHT AND COULD BECOME GUSTY AT TIMES. THE STRONGEST WINDS SHOULD BE FROM NEAR THE KPHL METRO ON SOUTH AND EAST. AN ISOLATED THUNDERSTORM CANNOT BE RULED OUT LATE SOUTH AND EAST OF KPHL. A POTENT LOW-LEVEL JET MOVES ACROSS THE AREA, AND THEREFORE LOW-LEVEL WIND SHEAR WAS INCLUDED FOR THE OVERNIGHT. MONDAY...IFR /LOCAL LIFR/ CEILINGS FOR AWHILE IN THE MORNING, THEN CEILINGS SHOULD RISE TO MVFR AND THEN PERHAPS VFR IN THE AFTERNOON AS A MUCH WARMER AIRMASS IS IN PLACE. IT IS POSSIBLE THOUGH THAT SOME LOW CLOUDS LINGER LONGER ESPECIALLY CLOSER TO THE COAST. RAIN DEPARTS EARLY, HOWEVER A FEW SHOWERS THROUGH THE DAY WILL BE POSSIBLE. SOUTHWESTERLY WINDS 15-20 KNOTS WITH GUSTS UP TO 30 KNOTS. THE CORE OF LOW-LEVEL JET SHIFTS FARTHER OFFSHORE DURING THE DAY, THEREFORE LOW-LEVEL WIND SHEAR SHOULD DECREASE DURING THE MORNING. OUTLOOK... MONDAY NIGHT INTO TUESDAY...CONDITIONS SHOULD RETURN TO VFR THROUGH THIS PERIOD. WEDNESDAY...A COASTAL STORM WILL LIKELY BRING MVFR OR IFR CEILINGS AND REDUCED VISIBILITIES DUE TO RA (POSSIBLY RASN AT TIMES) FOR THE REGION. IN ADDITION, EXPECT PERSISTENT NORTHERLY OR NORTHEASTERLY WINDS FOR GENERALLY THE LATTER HALF OF THE DAY. WEDNESDAY NIGHT...MVFR AND IFR CEILINGS CONTINUE. IN ADDITION, IF PRECIPITATION LINGERS FOR MUCH OF THE NIGHT, COULD SEE -SN AND REDUCED VISIBILITIES BECAUSE OF IT. THANKSGIVING...CONDITIONS SLOWLY RETURN TO VFR AND WINDS SHIFT TO WESTERLY.
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&& .MARINE...
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GALE WARNING IN EFFECT FROM MIDNIGHT TONIGHT THROUGH MONDAY MORNING. SEAS AND WINDS ARE EXPECTED TO INCREASE IN ADVANCE OF LOW PRESSURE MOVG FROM THE SRN PLAINS TO THE GRTLKS. THE ASSOCD WMFNT WILL MOVE THRU TONIGHT AND RAIN WILL OVERSPREAD THE WATERS TONIGHT. OUTLOOK... MONDAY...GALE CONDITIONS LOOK TO CONTINUE FOR GENERALLY THE FIRST HALF OF THE DAY. THEN WINDS AND SEAS WILL BE SLOW TO DECREASE BELOW SCA CRITERIA. TUESDAY...CONDITIONS SHOULD FALL BELOW SCA CRITERIA. WEDNESDAY...WINDS AND SEAS INCREASE IN THE LATER HALF OF THE DAY ABOVE SCA CRITERIA. THANKSGIVING...WINDS AND SEAS ARE EXPECTED TO FALL BELOW SCA CRITERIA EARLY IN THE DAY AND REMAIN BELOW CRITERIA THROUGH THE REST OF THE DAY.
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&& .CLIMATE...
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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 WITH THE POSSIBILITY OF A MIDWEEK COASTAL STORM BRINGING SNOW TO THE REGION, WE HAVE INCLUDED DAILY SNOWFALL RECORDS BELOW FOR OUR FOUR PRIMARY CLIMATE SITES THAT HAVE A LONG-STANDING UNBROKEN PERIOD OF RECORD (POR) WITH RESPECT TO HISTORICAL SNOWFALL DATA. DAILY SNOWFALL RECORDS: NOVEMBER 26TH: NOVEMBER 27TH: PERIOD OF RECORD: ACY: TRACE 1977,1957,1955 1.2 INCHES 1978 1874 PHL: 6.0 INCHES 1898 6.9 INCHES 1949,1938 1872 ILG: 0.1 INCHES 1950 4.5 INCHES 1978 1894 ABE: 1.7 INCHES 1925 7.0 INCHES 1938 1922
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...GALE WARNING FROM MIDNIGHT TONIGHT TO 11 AM EST MONDAY FOR ANZ430-431-450>455. && $$ SYNOPSIS...GORSE/JOHNSON NEAR TERM...GORSE SHORT TERM...NIERENBERG LONG TERM...JOHNSON AVIATION...GORSE/JOHNSON MARINE...JOHNSON/NIERENBERG CLIMATE...DRAG/KLINE

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