WINTER ANALOGS FOR 2011-2012 WINTER
ONCE AGAIN WE ARE EMBARKING ON THE SOJOURN AS TO HOW THE CURRENT
ENSO STATE AND FALL TEMPERATURES HAVE RELATED TO ENSUING WINTERS
IN THE PAST IN PHILADELPHIA.

AS THE LAST TWO WINTERS HAVE PROVEN, THE NORTH ATLANTIC
OSCILLATION (NAO) CAN THOROUGHLY TRUMPED THE PACIFIC ENSO STATE.
BOTH A STRONG EL NINO AND MODERATE LA NINA WERE
UNCHARACTERISTICALLY COLDER AND QUITE SNOWY WINTERS. NAO SEASONAL
OUTLOOKS REMAIN DIFFICULT TO VERIFY. WHILE ITS RARE TO HAVE THREE
CONSECUTIVE STRONGLY NEGATIVE NAO WINTERS IN A ROW, WE GET INTO A
HEAP OF TROUBLE WHEN WE START ANY METEOROLOGICAL SENTENCE WITH "WE
NEVER..."

LOOKING GLOBALLY THIS AUTUMN, OCTOBER NORTHERN HEMISPHERIC AND
EURASIAN SNOW COVER LAGGED VS THE PAST TWO OCTOBERS. IT WILL BE
ABOVE NORMAL IN NOVEMBER. THE NUMBER OF RECURVING NORTHERN
HEMISPHERIC TROPICAL SYSTEMS (A PAPER ABOUT HEAT REDISTRIBUTION BY
ASSOCIATE PROFESSOR ROBERT HART AT FLORIDA STATE UNIVERSITY) THAT
REACHED 40N WAS WITHIN THE NORMAL TEMPERATURE RANGE. WE ARE
ENTERING THE NEGATIVE PHASE OF THE QUASI-BIENNIAL OSCILLATION
(QBO) THAT NORMALLY FAVORS MORE STRATOSPHERIC WARMING EVENTS AND
THUS HIGH LATITUDE BLOCKING. THE NEWFOUNDLAND SEA SURFACE
TEMPERATURE ANOMALY POOL (A METHOD OF TRYING TO OUTLOOK THE NAO)
AVERAGED NEAR NORMAL PRIOR TO THE RUSH OF THE PAST HURRICANE
SEASON. THIS WOULD FAVOR A CLOSER TO NEUTRAL NORTH ATLANTIC
OSCILLATION FOR THE UPCOMING WINTER. THE INDIAN OCEAN SEA SURFACE
TEMPERATURE ANOMALIES ARE WARMER THAN AVERAGE, A FLIP FROM LAST
WINTER. THE PACIFIC DECADAL OSCILLATION REMAINS NEGATIVE (WARMEST
WATER RELATIVE TO NORMAL IN THE WESTERN PACIFIC). THIS NORMALLY
WOULD NOT FAVOR A PREVAILING COLDER POSITIVE PACIFIC NORTH
AMERICAN TELECONNECTION (PNA). THE LATEST WEEKLY ENSO READING IS
IN THE WEAK LA NINA CATEGORY. NEARLY ALL GLOBAL STATISTICAL AND
DYNAMICAL MODELS ARE OUTLOOKING EITHER A WEAK OR MODERATE LA NINA
FOR THIS UPCOMING WINTER. MOST HAVE IT AS AN EARLY NEGATIVE PEAK
WEAKENING (OR WARMING) AS THE WINTER PROGRESSES.

AS FOR OUR OWN BACKYARD, THIS PAST OCTOBER, WHILE ABOVE AVERAGE,
FELL WITHIN THE "NORMAL" THIRD OF ALL OCTOBERS. THIS NOVEMBER WILL
FALL INTO THE "WARM" THIRD OF ALL NOVEMBERS, RANKING SOMEWHERE
AROUND THE 10TH WARMEST. THE LA NINA STATE AND THE OCTOBER AND
NOVEMBER TEMPERATURE DEPARTURES LEFT US WITH SLIM ANALOG PICKINGS.
TO HAVE AT LEAST FOUR ANALOGS, WE EXPANDED OUR POOL TO INCLUDE
WINTERS WITH NEGATIVE (COLDER) ENSO VALUES, EVEN IF THEY DID NOT
REACH THE FORMAL NINA DEFINITION. MOST OF THE ANALOGS WERE THE
SECOND OR LATER WINTER SEASONS IN A STRING OF MULTIPLE WINTER NINA
SEASONS. MOST ALSO HAD ABOVE NORMAL NOVEMBER NORTHERN HEMISPHERIC
SNOW AND ICE COVER.

FOR BETTER OR WORSE THIS IS THIS WINTER`S VERSION OF OUR PHIL FAB
FOUR:

SEASON         DEC      JAN      FEB    WINTER    SEASONAL   WINTER
               AVG      AVG      AVG      AVG     SNOWFALL*  PCPN

1945-6         29.8     33.8     34.5     32.7       19.0    7.18
1998-9         42.0     35.0     38.0     38.3       12.8    8.66
1999-0         39.9     32.1     37.5     36.5       21.3    8.23
2008-9         35.9     29.1     37.1     34.0       23.2    9.12

AVG            36.9     32.5     36.8     35.4       19.1    8.30
1981-2010 NML  37.5     33.0     35.7     35.4       22.4    9.24

* THIS INCLUDES THE 0.3" THAT FELL IN OCTOBER. OUR RESEARCH HAS
ALWAYS BEEN TEMPERATURE BASED. IT IS DOUBTFUL THAT THIS DECEMBER
WILL BE AS COLD AS DECEMBER 1945. SINCE NATURE REALLY DOES NOT
RECOGNIZE MONTHS (AS WE DO), WE WOULD VIEW THIS AS AN INDICATION OF
A COLD STRETCH OR MONTH DURING DECEMBER AND OR JANUARY THIS UPCOMING
WINTER. AS A REMINDER THE SNOWFALL GOES ALONG FOR THE RIDE WITH THE
TEMPERATURES IN THE WINTER ANALOGS. WE SHOULD HAVE RETIRED AFTER THE
WINTER OF 2008-9 WHEN WE CAME WITHIN HALF AN INCH OF THE ACTUAL
SNOWFALL AMOUNT. DURING THE LAST TWO WINTER SEASONS, THE SNOWFALL
PART FAILED MISERABLY.

CLIMATOLOGICALLY SPEAKING WEAK TO MODERATE LA NINA WINTERS TEND
TO AVERAGE AROUND NORMAL TO SLIGHTLY BELOW NORMAL WITH RESPECT TO
BOTH TEMPERATURES AND SNOWFALL. THE WEAKER THE NINA, THE COLDER
AND SNOWIER THE WINTERS HAVE AVERAGED. LARGER SNOWS (6 INCHES OR
GREATER SINGLE EVENTS AS MEASURED AT PHL) ARE CLOSE TO THE
CLIMATOLOGICAL AVERAGE OF NEARLY ONE PER SEASON IN WEAK NINA
WINTERS. UNDER MOST CIRCUMSTANCES, THEY AVERAGE LESS THAN THE
CLIMATOLOGICAL NORM IN MODERATE OR STRONGER NINA WINTERS. LAST
WINTER PROVED THERE ARE EXCEPTIONS. IT WAS THE SNOWIEST MODERATE
OR STRONG LA NINA ON RECORD IN PHILADELPHIA.

THE OFFICIAL CPC OUTLOOK FOR THE WINTER IS FOR EQUAL CHANCES OF
IT IT BEING EITHER WARMER OR COOLER THAN NORMAL AND EITHER WETTER
OR DRIER THAN NORMAL.

WE WANT TO WISH EVERYONE A VERY HAPPY AND HEALTHY WINTER SEASON.

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