Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 280555
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1255 AM EST FRI NOV 28 2014

.SYNOPSIS...
HIGH PRESSURE IS FORECAST TO BUILD ACROSS THE EAST COAST FRIDAY
INTO FRIDAY NIGHT, 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.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A WEAK IMPULSE IN THE MID LEVEL FLOW WAS BEGINNING TO PASS OVER
OUR FORECAST AREA AROUND MIDNIGHT. A MORE SUBSTANTIAL SHORT WAVE
IS EXPECTED TO FOLLOW TOWARD DAYBREAK. WE ARE ANTICIPATING AN
INCREASE IN CLOUD COVER FOR A TIME OVERNIGHT AS A RESULT OF THESE
FEATURES. ALSO, SCATTERED SNOW FLURRIES ARE ANTICIPATED TO PASS
ACROSS OUR NORTHWESTERN COUNTIES WITH LITTLE OR NO ACCUMULATION
EXPECTED.

A WEST NORTHWEST WIND AROUND 5 TO 10 MPH IS FORECAST FOR THE
OVERNIGHT PERIOD WITH LOW TEMPERATURES MAINLY IN THE 20S.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 AM SATURDAY/...
THE UPPER TROUGH AXIS IS EXPECTED TO PROGRESS EAST OF THE MID-
ATLANTIC REGION BY 12Z FRIDAY. SUBSIDENCE IN ITS WAKE WILL BE
ACCOMPANIED BY CLEARING SKIES AND DRY WEATHER FOR BLACK FRIDAY. A
CAA REGIME UNDER NORTHWEST FLOW BEHIND THE TROUGH WILL PERSIST AS
WELL. SO DESPITE SUNSHINE TOMORROW VS CLOUDY SKIES TODAY, MAX
TEMPS FRIDAY WILL BE SEVERAL DEGREES COOLER THAN TODAY. HIGHS
RANGE FROM THE UPPER 20S IN THE POCONOS TO NEAR 40F ALONG THE
COAST.

EXPECT WINDS TO BE BREEZY (GUSTS 20-25 MPH) IN THE MORNING AS
HIGH PRESSURE BUILDS IN FROM THE TENNESSEE VALLEY. THE WINDS RELAX
A BIT LATE IN THE DAY WHEN THE HIGH SHIFTS OVERHEAD.

&&

.LONG TERM /SATURDAY THROUGH FRIDAY/...
HIGH PRESSURE OVER THE AREA FRIDAY NIGHT WILL BEGIN TO MOVE TO
OUR SOUTH AND EAST BY SATURDAY AND SATURDAY NIGHT. SEVERAL WEAK
SHORT WAVE/VORTICITY IMPULSES ARE FORECAST TO SLIDE ACROSS THE
AREA FRIDAY NIGHT, SATURDAY, AND SATURDAY NIGHT, ALONG WITH AN
INCREASE IN MOISTURE ALOFT ACROSS THE NORTHERN AREAS. THERE IS
SOME TIMING DIFFERENCES, BUT THERE IS SOME POTENTIAL FOR SOME
LIGHT PRECIPITATION TO DEVELOP DURING THIS TIME PERIOD. WE WILL
KEEP A SLIGHT CHANCE OF SHOWERS ACROSS OUR NORTHERN ZONES WHERE
THEY HAVE A BETTER CHANCE OF SQUEEZING OUT SOME MOISTURE. ANYTHING
THAT WOULD FALL IS EXPECTED TO BE LIGHT.

ON SUNDAY, WE WILL BE IN BETWEEN THE HIGH TO OUR EAST AND AN
APPROACHING COLD FRONT. ANOTHER WEAK SHORT WAVE/VORTICITY IMPULSE
AND MOISTURE PLUME ALOFT SPREAD ACROSS THE NORTHERN HALF OF THE
AREA SUNDAY, SO THERE REMAINS A SLIGHT CHANCE OF SHOWERS SUNDAY.

A FRONTAL BOUNDARY IS EXPECTED TO SAG TOWARD THE AREA SUNDAY
NIGHT, THEN SLOWLY MOVE THROUGH THE AREA INTO MONDAY INTO MONDAY
NIGHT. THERE CONTINUES TO BE SOME SLIGHT DIFFERENCES WITH THIS
BOUNDARY WITH THE GFS THE FASTEST, THE CANADIAN THE SLOWEST, AND
THE ECMWF IN BETWEEN. ALSO THERE AREA DIFFERENCES WITH QPF
AMOUNTS, SO WE WILL KEEP CHANCE/SLIGHT CHANCE POPS ACROSS THE AREA
DURING THIS PERIOD.

THE FRONT SHOULD PUSH TO OUR SOUTH AS HIGH PRESSURE BRIEFLY
BUILDS ACROSS THE NORTHEAST TUESDAY. THE GFS AND ECMWF INDICATE
DRIER AIR BUILDING ACROSS THE AREA DURING THE DAY, SO WE MAKE THE
FORECAST DRY FOR TUESDAY DAY.

ANOTHER FRONTAL SYSTEM IS EXPECTED TO AFFECT THE AREA AROUND NEXT
WEDNESDAY. A WARM FRONT MAY LIFT ACROSS THE AREA TUESDAY NIGHT AS
THE HIGH RETREATS NORTHEASTWARD, BEFORE A COLD FRONT MOVES ACROSS
THE AREA ON WEDNESDAY. PRECIPITATION CHANCES INCREASE TUESDAY INT
WEDNESDAY, THEN LOWER BEHIND THE FRONT WEDNESDAY NIGHT INTO
THURSDAY AS HIGH PRESSURE BUILDS BACK ACROSS THE NORTHEAST AGAIN.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

VFR CONDITIONS ARE FORECAST THROUGH THE TAF PERIOD. WE ARE
ANTICIPATING AN INCREASE IN CLOUDS OVERNIGHT FOLLOWED BY SOME
CLEARING FOR THE DAYLIGHT HOURS ON FRIDAY. INCREASING AND LOWERING
CLOUDS ARE EXPECTED FOR FRIDAY NIGHT.

A WEST NORTHWEST WIND AROUND 5 TO 10 KNOTS IS FORECAST FOR THE
OVERNIGHT PERIOD. THE WIND SPEEDS SHOULD INCREASE TO 8 TO 12 KNOTS
DURING THE DAYLIGHT HOURS ON FRIDAY WITH GUSTS NEAR 20 KNOTS. THE
WIND IS EXPECTED TO BECOME LIGHT AND VARIABLE ON FRIDAY NIGHT AS
HIGH PRESSURE BUILDS ACROSS OUR REGION.

OUTLOOK...
FRIDAY NIGHT-MONDAY...MOSTLY VFR. WIND GUSTS 15-20 KNOTS EACH
DAY; SOUTHWEST SATURDAY & SUNDAY, AND NORTHWEST ON MONDAY.

MONDAY NIGHT...CHANCE OF RAIN OR SNOW SHOWERS. GENERALLY VFR
UNLESS PRECIPITATION OCCURS. GUSTY NORTHWEST WINDS AROUND 20 KNOTS
POSSIBLE.

TUESDAY...MOSTLY VFR.

&&

.MARINE...
A NEW SCA WAS ISSUED FOR TONIGHT AND FRIDAY FOR THE DE BAY AND
MOST OF THE OCEAN ZONES TO COVER THE EXPECTED NORTHWEST PRESSURE
SURGE. MIXING WILL BE EFFECTIVE WITH EVEN COLDER AIR MOVING ABOVE
THE RELATIVELY WARMER WATERS. THE ONE EXCEPTION TO THE SCA IS THE
COASTAL WATERS FROM SANDY HOOK TO MANASQUAN INLET. THE SCA FOR
THIS NORTHERN MOST ZONE IS ONLY IN EFFECT FRIDAY SINCE THE
PRESSURE GRADIENT WILL BE A BIT WEAKER TONIGHT AND THE GUST
POTENTIAL SHOULD BE CAPPED AROUND 20 KT.

OUTLOOK...
FRIDAY NIGHT-SATURDAY...SUB-SMALL CRAFT ADVISORY CONDITIONS
EXPECTED AS HIGH PRESSURE BUILDS OVER THE WATERS.

SATURDAY-SUNDAY NIGHT...SMALL CRAFT ADVISORY CONDITIONS POSSIBLE
AS HIGH PRESSURE PUSHES TO OUR SOUTH AND COLD FRONT APPROACHES
LATE ON SUNDAY NIGHT.

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.

&&

.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 IS HAVING A GREAT THANKSGIVING AND WE HOPE YOU
WILL HAVE A HAPPY UPCOMING HOLIDAY SEASON. MAY THIS WINTER BE
BEYOND YOUR WILDEST EXPECTATIONS.

&&

.EQUIPMENT...
KDIX WSR-88D RADAR IS INOPERATIVE. TECHNICIANS HAVE BEEN NOTIFIED
AND WILL TROUBLESHOOT THE ISSUE. TPHL TDWR SHOULD PROVIDE
SUFFICIENT BACKUP RADAR COVERAGE.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ430-
     431-451>455.
     SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 6 PM EST THIS
     EVENING FOR ANZ450.

&&

$$

SYNOPSIS...ROBERTSON
NEAR TERM...IOVINO
SHORT TERM...KLEIN
LONG TERM...ROBERTSON
AVIATION...IOVINO/ROBERTSON
MARINE...KLEIN/ROBERTSON
CLIMATE...GIGI
EQUIPMENT...STAFF






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