Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 281140 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 640 AM EST FRI NOV 28 2014 .SYNOPSIS...
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HIGH PRESSURE IS FORECAST TO BUILD ACROSS THE EAST COAST FROM TODAY INTO TONIGHT, BEFORE MOVING TO THE SOUTH AND EAST SATURDAY INTO SATURDAY NIGHT. A WARM FRONT MAY LIFT NORTH OF THE AREA SATURDAY NIGHT INTO SUNDAY. A COLD FRONT IS EXPECTED TO SAG DOWN ACROSS THE AREA SUNDAY NIGHT, BEFORE SLOWLY MOVING THROUGH THE AREA MONDAY INTO MONDAY NIGHT. HIGH PRESSURE WILL THEN BRIEFLY RETURN TO THE NORTHEAST FOR TUESDAY, FOLLOWED BY ANOTHER FRONTAL SYSTEM AROUND WEDNESDAY.
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&& .NEAR TERM /THROUGH TONIGHT/...
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A MID LEVEL SHORT WAVE TROUGH WAS PASSING OVERHEAD EARLY THIS MORNING. THE FEATURE WILL MOVE OUT TO SEA. CLOUDS AND SCATTERED SNOW SHOWERS AND FLURRIES WILL LINGER IN OUR NORTHERN COUNTIES EARLY THIS MORNING IN THE DEVELOPING NORTHWEST FLOW. A FEW TENTHS OF AN INCH OF NEW SNOW IS POSSIBLE, MAINLY IN THE ELEVATED TERRAIN. OTHERWISE, WE ARE ANTICIPATING A MOSTLY SUNNY SKY FOR TODAY AS DRY AIR BUILDS INTO OUR REGION. HIGH CLOUDS MAY BEGIN TO OVERSPREAD OUR REGION FROM THE NORTHWEST DURING THE AFTERNOON. A GUSTY NORTHWEST WIND IS EXPECTED TO DEVELOP THIS MORNING AS THE SHORT WAVE MOVES FARTHER TO OUR EAST. WE ARE FORECASTING WIND SPEEDS AROUND 10 TO 15 MPH WITH GUSTS INTO THE 20S. MAXIMUM TEMPERATURES SHOULD RANGE FROM THE UPPER 20S IN THE POCONOS TO AROUND 40 DEGREES IN FAR SOUTHERN NEW JERSEY AND IN SOUTHERN DELAWARE.
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&& .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... HIGH CLOUDS WILL CONTINUE TO BUILD OVERHEAD THIS EVENING. WARM ADVECTION IS FORECAST TO BEGIN OVER OUR REGION AS THE SURFACE RIDGE PASSES OFF THE COAST. WE ARE ANTICIPATING MID LEVEL CLOUDS TO DEVELOP IN THE ISENTROPIC LIFT. CEILINGS ARE EXPECTED TO LOWER GRADUALLY LATE TONIGHT AND WE MAY SEE SOME LIGHT SNOW SHOWERS POKE INTO OUR FORECAST AREA FROM THE WEST. ONLY A VERY LIGHT ACCUMULATION IS ANTICIPATED WITH THE BEST CHANCE IN OUR FORECAST AREA BEING IN EASTERN PENNSYLVANIA. THE WIND IS EXPECTED TO BECOME LIGHT AND VARIABLE. FAIRLY GOOD RADIATING CONDITIONS MAY BE PRESENT DURING THE EVENING AND TEMPERATURES ARE FORECAST TO FALL INTO THE TEENS IN OUR NORTHERN COUNTIES AND INTO THE 20S ELSEWHERE OVERNIGHT. && .LONG TERM /SUNDAY THROUGH THURSDAY/...
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OVERALL LOOKS LIKE A FAIRLY BENIGN PATTERN FOR THE MID-ATLANTIC REGION OVER THE NEXT FEW DAYS...WITH NO BIG STORMS ON THE HORIZON AND TEMPS GENERALLY WITHIN A FEW DEGREES OF NORMAL. THE FLOW ALOFT IS MAINLY ZONAL OVR THE NRN US WITH A COUPLE OF SHRTWV TROFS MOVG THROUGH ON MON AND AGAIN AROUND WED/THU. THE LATTER ONE IS FCST TO DIG A LITTLER DEEPER OVER THE ERN US AND HAS A BETTER CHC TO PRODUCE SOME LIGHT PRECIP. THE BEST ASSOCD FORCING FOR UVV REMAINS TO OUR NORTH AND MOISTURE SEEMS RATHER LIMITED. FOR SATURDAY...THE CURRENT COLD AIR MASS WILL BE LIFTING AWAY TO THE NE AND RESULTING WAA WILL PRODUCE CLOUDS AND POSSIBLY SOME LIGHT SNOW IN THE MORNING...MAINLY N OF PHL. AS HIGH PRES MOVES OFF THE COAST...WINDS BECOME SWLY AND CONTINUE THRU SUN AND MON AHEAD OF A COLD FRONT APPROACHING FROM THE NW. MAX TEMPS ON SUN/MON SHOULD BE A FEW DEGS ABOVE NORMAL. ATTM IT LOOKS LIKE THE FROPA WOULD BE SOMETIME AROUND MIDDAY MONDAY. THE FCST HAS CHC POPS FOR MON/MON NIGHT WITH POSSIBLY SOME LIGHT SNOW IN CAA BEHIND THE FRONT. HIGH PRES MOVES BY RATHER QUICKLY TO THE NORTH ON TUE...FOLLOWED BY ANOTHER FRONTAL SYSTEM ON WED. THIS ONE SEEMS TO HAVE A SLIGHTLY BETTER FORCING AND MOISTURE CONNECTION AND POPS ARE SLIGHTLY HIGHER FOR WED THAN MON. HWVR THERE IS A LOT OF UNCERTAINTY THAT FAR OUT. ATTM IT LOOKS LIKE TEMPS SHOULD BE WARM ENOUGH FOR MOSTLY RAIN.
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&& .AVIATION /12Z FRIDAY THROUGH TUESDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. MAINLY VFR CONDITIONS ARE FORECAST THROUGH THE TAF PERIOD. EARLY MORNING CLOUDS SHOULD BE FOLLOWED BY CLEARING FOR THE DAYLIGHT HOURS. INCREASING AND LOWERING CLOUDS ARE EXPECTED FOR TONIGHT. THERE IS A CHANCE OF LIGHT SNOW SHOWERS AND FLURRIES LATE TONIGHT, ESPECIALLY AROUND KRDG AND KABE WHERE CONDITIONS MAY LOWER BRIEFLY INTO THE MVFR RANGE. A WEST NORTHWEST WIND AROUND 5 TO 10 KNOTS IS FORECAST FOR THE EARLY MORNING. THE WIND SPEEDS SHOULD INCREASE TO 8 TO 12 KNOTS DURING THE DAYLIGHT HOURS WITH GUSTS NEAR 20 KNOTS. THE WIND IS EXPECTED TO BECOME LIGHT AND VARIABLE TONIGHT AS HIGH PRESSURE BUILDS ACROSS OUR REGION. OUTLOOK... SATURDAY-MONDAY...MOSTLY VFR. WIND GUSTS 15-20 KNOTS EACH DAY; SOUTHWEST SATURDAY & SUNDAY, BECOMING NORTHWEST ON MONDAY. MONDAY NIGHT...CHANCE OF RAIN OR SNOW SHOWERS. GENERALLY VFR CONDS BUT TEMPORARILY LOWER IN PRECIPITATION. GUSTY NORTHWEST WINDS AROUND 20 KNOTS POSSIBLE. TUESDAY...MOSTLY VFR WITH NORTH WINDS.
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&& .MARINE...
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A MID LEVEL SHORT WAVE TROUGH WAS PASSING OVERHEAD EARLY THIS MORNING. THE WEST NORTHWEST WIND WILL INCREASE IN ITS WAKE AND WIND GUSTS AROUND 25 OR 30 KNOTS ARE POSSIBLE ON OUR COASTAL WATERS, INCLUDING ON DELAWARE BAY, FOR MUCH OF THE DAY. AS A RESULT, A SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 600 PM. HIGH PRESSURE IS EXPECTED TO BUILD OVER OUR REGION FROM THE WEST FOR TONIGHT AND WIND SPEEDS WILL LIKELY DIMINISH. OUTLOOK... SATURDAY-SUNDAY...SUB-SMALL CRAFT ADVISORY CONDITIONS EXPECTED AS THE CENTER OF HIGH PRESSURE MOVES OUT OVER THE WATERS. MONDAY-MONDAY NIGHT...SMALL CRAFT ADVISORY CONDITIONS REMAIN POSSIBLE BEHIND THE COLD FRONT THAT MOVES ACROSS THE AREA. TUESDAY...SUB-SMALL CRAFT ADVISORY CONDITIONS EXPECTED AS HIGH PRESSURE AFFECTS THE WATERS.
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&& .CLIMATE... WITH THANKSGIVING UPON US AND METEOROLOGICAL WINTER KNOCKING ON OUR DOOR, ITS OUR ANNUAL LOOK TO SEE HOW PAST WINTERS HAVE FARED BASED ON PRECEDING FALL PATTERNS AND TRENDS. OUR FORAY LAST FALL ABOUT THE WINTER OF 2013-14 WAS AN UNMITIGATED BUST AS THE NEGATIVE EASTERN PACIFIC OSCILLATION PATTERN (EPO) TOOK HOLD IN NOVEMBER AND NEVER LET GO THE ENTIRE WINTER. WHILE THE COLDER NOVEMBER TRENDED DOWN OUR WINTER TEMPERATURE ANALOGS TO ABOUT NORMAL, IT WAS NOWHERE NEAR ENOUGH. IT WAS ALSO ONLY THE SIXTH TIME (OUT OF FORTY SIX OCCURRENCES) THAT A BOTTOM THIRD WINTER FOLLOWED A WARM OCTOBER. ONCE AGAIN WE ARE HEADING INTO THIS WINTER WITH A RARER COMBINATION OF A WARM OCTOBER AND COLDER NOVEMBER JUST LIKE THE TWO PREVIOUS AUTUMNS. IN TERMS OF ENSO, THE LATEST CONSENSUS OF ALL DYNAMICAL AND STATISTICAL MODELS FOR THE WINTER SEASON IS FOR A WEAK EL NINO TO OCCUR. OF LATE THE EL NINO HAS LOOKED HEALTHIER AS A KELVIN WAVE AND A CURRENTLY ROBUST MJO CYCLE HAVE/WILL HELP BOOST SEA SURFACE TEMPERATURE ANOMALIES (SSTA). AS CPC HAS STATED, THERE IS STILL A SSTA AND ATMOSPHERIC RESPONSE DISCONNECT THAT EXISTS. THE LATEST GLOBAL WIND OSCILLATION READINGS, OUR ATMOSPHERE IS STILL IN AN ENSO NEUTRAL STATE EVEN IF WATER EASTERN TROPICAL PACIFIC TEMPERATURE ANOMALIES HAVE BECOME WARMER. WEAK EL NINOS SINCE 1950 IN PHILADELPHIA HAVE HAD AN AVERAGE TEMPERATURE OF 33.2 DEGREES AND AVERAGE SNOWFALL OF 21.8 INCHES. WEAK EL NINOS, LIKE MOST NON-UBER EL NINOS, FAVOR HAVING MORE MAJOR SNOW STORMS THAN THE CLIMATOLOGICAL AVERAGE. IN THE TEN WEAK EL NINOS SINCE 1950, PHILADELPHIA HAS HAD EIGHT SNOWFALL EVENTS OF SIX INCHES OR MORE, FOUR OF WHICH WERE TEN INCHES OR MORE. THE MOST COMMON MONTH FOR MAJOR SNOWS DURING WEAK EL NINOS IS JANUARY, BUT THEY HAVE OCCURRED IN EVERY MONTH FROM NOVEMBER THROUGH MARCH. LOOKING AT THE MIDDLE AND HIGH LATITUDES, ONCE AGAIN SNOW COVERAGE IN EURASIA WAS OFF TO THE RACES IN SEPTEMBER AND OCTOBER, EVEN FASTER THAN AUTUMN OF 2013. OCTOBER 2014 ONLY TRAILED OCTOBER 1976 FOR TOTAL SNOW COVERAGE. IN THE SATELLITE ERA WHEN BOTH SEPTEMBER AND OCTOBER HAVE HAD ABOVE AVERAGE SNOW COVERAGE, 64 PERCENT OF THE ENSUING PHILADELPHIA WINTERS HAVE BEEN SNOWIER THAN THE CURRENT AVERAGE AND HAD A 50/50 SPLIT WITH TEMPERATURES BEING EITHER ABOVE OR BELOW NORMAL. WHILE 64 PERCENT MAY NOT SOUND DEFINITIVE, SNOWFALL IS NOT A NORMAL DISTRIBUTION BECAUSE SEASONS LIKE 2013-14 SKEW UPWARD THE STATISTICAL AVERAGE. SINCE 1967 (THE START OF THE SATELLITE ERA AND OUR LOOK AT THE DR. JUDAH COHEN STUDY) ONLY 1 IN 3 WINTERS HAS HAD ABOVE AVERAGE SNOWFALL. THE STATISTICAL MEDIAN FOR SNOWFALL IN PHILADELPHIA SINCE 1967 IS ABOUT 18 INCHES. BEYOND SIBERIA, THE ARCTIC OSCILLATION AVERAGED NEGATIVE DURING THE MONTH OF OCTOBER. WHEN IT HAS, 70 PERCENT OF ENSUING WINTERS HAS AVERAGED NEGATIVE. THANK-YOU METEOROLOGIST MATT LANZA FOR THIS INFORMATION. ANOTHER PHENOMENON THAT FAVORS A NEGATIVE ARCTIC OSCILLATION FOR THIS UPCOMING WINTER IS THAT WE ARE IN THE EASTERLY PHASE OF THE QUASI-BIANNUAL OSCILLATION STRATOSPHERIC WINDS OVER THE TROPICS. WHEN WE ARE IN THIS PHASE, HISTORICALLY WE HAVE HAD MORE SUDDEN STRATOSPHERIC WARMING EVENTS WHICH OFTEN SPLITS AND DISPLACES EVERYBODY`S FAVORITE POLAR VORTEX FROM NEAR THE NORTH POLE. THERE IS NO GUARANTEE THE WESTERN HEMISPHERE WOULD BE THE SO CALLED BENEFICIARY OF THIS ARCTIC DISPLACEMENT, BUT A HIGHER CHANCE EXISTS THIS WINTER VS NO CHANCE AT ALL. THE ARCTIC OSCILLATION`S COUSIN, THE NORTH ATLANTIC OSCILLATION (NAO), WE HAVE SEEN BEEN THE DRIVER (WINTER OF 2010-11) OR THE CRICKET CHIRPING (LAST WINTER) RECENTLY. UNFORTUNATELY THIS IMPORTANT TELECONNECTION INDEX IS TOUGH TO OUTLOOK MORE THAN WEEKS IN ADVANCE. WHILE THE ARCTIC OSCILLATION AND NORTH ATLANTIC OSCILLATION NORMALLY WORK IN TANDEM, ITS NOT ALWAYS THE CASE. SINCE 1950, 60 PERCENT OF ALL WINTERS HAVE AVERAGED A NEGATIVE ARCTIC OSCILLATION, BUT ONLY 42 PERCENT OF ALL WINTERS HAVE AVERAGED A NEGATIVE NORTH ATLANTIC OSCILLATION. THE LATE JACK ORDILLE POINTED US TO A RESEARCH PAPER USING NEWFOUNDLAND REGION SPRING-SUMMER SEA SURFACE TEMPERATURE ANOMALIES AS A PREDICTOR OF THE NAO FOR THE ENSUING WINTER. IT HAS WORKED WELL THE LAST COUPLE OF WINTERS (HERE COMES THE JINX) AND IT FAVORS A NEGATIVE NAO FOR THIS UPCOMING WINTER. THIS BRINGS US TO OUR LAST (BUT NOT LEAST) OSCILLATION INDEX, THE PACIFIC DECADAL OSCILLATION (PDO). CURRENTLY THE OSCILLATION IS IN TEXTBOOK POSITIVE POSITION. SO MUCH SO, THAT WHEN ITS BEEN THIS POSITIVE DURING THE MONTH OF OCTOBER, IT HAS NEVER AVERAGED NEGATIVE (HERE COMES ANOTHER ANNOUNCER`S JINX: 15 OF 15 TIMES SINCE 1900) DURING THE UPCOMING WINTER. ELEVEN OF THOSE WINTERS HAVE AVERAGED COLDER THAN THE CURRENT AVERAGE (AND AVERAGED AROUND 20 INCHES OF SNOW) IN PHILADELPHIA. HISTORICALLY ABOUT 2/3RDS OF ALL WINTERS SINCE 1900 HAVE AVERAGED COLDER THAN NORMAL IN PHILADELPHIA WHEN THE PDO HAS AVERAGED POSITIVE. IN FACT, THE GREATEST POINT OF FAILURE WHEN WARM OCTOBERS HAVE NOT BEEN FOLLOWED BY WARMER WINTERS HAS BEEN WHEN THE PDO HAS BEEN STRONGLY POSITIVE IN THE AUTUMN. LOCALLY, OF THE 46 WARMEST WINTERS IN PHILADELPHIA ON RECORD, HALF OF THEM HAVE OCCURRED AFTER A WARM OCTOBER. GIVEN THE STATE OF THE PDO, WE DONT HAVE A WARM FEELING ABOUT THAT THIS WINTER. THIS NOVEMBER WILL END AGAIN CLOSE TO THE CUSP BETWEEN THE UNSEASONABLY COLD AND NORMAL TERCILES. REGARDLESS THIS IS A RARER OCCURRENCE AND A CONTRADICTION IN THE STUDY FIRST DONE IN WHICH THE STRONGEST CORRELATOR FOR A WARM WINTER IS A WARM OCTOBER WHILE THE STRONGEST CORRELATOR FOR A COLD WINTER IS A COLD NOVEMBER. IN 2012 OCTOBER WON, LAST YEAR NOVEMBER WON. UNLIKE THE LAST TWO WINTERS, WE ARE EXPECTING A WEAK EL NINO AND NOT ENSO NEUTRAL NEGATIVE. WHILE THE PACIFIC FAVORS COLD AGAIN, THE TYPE OF COLD LOOKS DIFFERENT AS POSITIVE SEA SURFACE TEMPERATURE ANOMALIES ARE FARTHER EAST THAN THEY WERE LAST AUTUMN. SO HERE ARE OUR ANALOGS FOR THE UPCOMING WINTER. THEY ARE BASED ON WARMER THAN CURRENT NORMAL OCTOBERS AND COLDER THAN CURRENT NORMAL NOVEMBERS. THE ANALOGS ARE A COMBINATION OF MODERATE, WEAK AND ENSO POSITIVE WINTERS. SEVEN OF THESE ALSO HAD POSITIVE PDO(S) DURING THE WINTER, THE ONE EXCEPTION (1953-4) WE KEPT BECAUSE IT WAS A WEAK EL NINO AND IT ALSO WAS A SNOWY NOVEMBER. AS ALWAYS PAST PERFORMANCE MAY NOT BE AN INDICATOR OF FUTURE TRENDS....AND NOW TO THE GREAT EIGHT: SEASON DEC JAN FEB WINTER SEASONAL WINTER AVG AVG AVG AVG SNOWFALL PCPN 1905-06 39.2 39.4 33.6 37.4 20.5 8.61 1914-15 33.3 36.6 38.6 36.2 32.5 19.64 1939-40 38.1 25.3 34.8 32.7 22.3 7.77 1941-42 38.3 30.5 30.8 33.2 10.3 9.24 1951-52 38.7 37.3 38.2 38.1 16.2 12.21 1953-54 39.4 31.7 41.7 37.6 22.6 7.58 1986-87 37.9 31.9 32.5 34.1 25.7 11.64 2002-03 35.4 28.6 29.9 31.3 46.3 11.02 AVG 37.5 32.7 35.0 35.1 24.6 11.59 1981-2010 NML 37.5 33.0 35.7 35.4 22.4 9.24 THE OFFICIAL CPC OUTLOOK FOR THE WINTER IS FOR EQUAL CHANCES OF IT BEING EITHER WARMER OR COLDER THAN NORMAL AND A GREATER CHANCE OF IT BEING WETTER THAN NORMAL. WE HOPE EVERYONE HAD A GREAT THANKSGIVING AND WE HOPE YOU WILL HAVE A HAPPY UPCOMING HOLIDAY SEASON. MAY THIS WINTER BE BEYOND YOUR WILDEST EXPECTATIONS. && .EQUIPMENT...
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KDIX WSR-88D RADAR IS INOPERATIVE. TECHNICIANS HAVE BEEN NOTIFIED AND WILL TROUBLESHOOT THE ISSUE. TPHL TDWR SHOULD PROVIDE SUFFICIENT BACKUP RADAR COVERAGE.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ430- 431-450>455. && $$ SYNOPSIS...AMC NEAR TERM...IOVINO SHORT TERM...IOVINO LONG TERM...AMC AVIATION...AMC/IOVINO MARINE...AMC/IOVINO CLIMATE...GIGI EQUIPMENT...STAFF

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