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Winter 2013-2014


Rainshadow

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For those who are interested, the following are some statistics related to the AO, ENSO and Philadelphia's seasonal snowfall. Apparently, one of my snowfall amounts referenced in #320 was incorrect. I regret the error. This data incorporates the correct seasonal snowfall amount.

 

PHLSno.jpg

 

Don,

 

Great info as always. I can tell you since 1950 the NAO has been negative or was negative in the days leading up to 6 inch or great events in PHL 64% of the time and 71% of the time for single events greater than or equal 10 inches.

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For those who are interested, the following are some statistics related to the AO, ENSO and Philadelphia's seasonal snowfall. Apparently, one of my snowfall amounts referenced in #320 was incorrect. I regret the error. This data incorporates the correct seasonal snowfall amount.

 

PHLSno.jpg

 

Don,

do you have some stats on how often the NAO and AO are in the same state--in other words, what percentage of time is there a -AO with a -NAO?

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I did some quick math and barring the early of next week not being somewhat torchy and/or the last week not being cold, looks like this November should end in the "normal third".  It seems of late we have not had many enso neutral years as many of the analogs are quite old and kind of bland in the snowfall department.

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November is going to make a run for a bottom third.  Given that 2012-13 is in that warm/cold list and this December has no low 40s look to it, this analog list is going to be ancient, not too many warm Octobers have been followed by chilly Novembers.

 A difficult year to pattern. Does a cool August/September/November mean anything?

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 A difficult year to pattern. Does a cool August/September/November mean anything?

 

I looked at September when I first did this study for NYC winters in the 80s and there was some lean in the same direction as its departure for the following winter, but not on the same level of either October and November.  I never looked at August.  BTW the best ranked correlators for the ensuing winters in term of chi square testing (they all are in the same temp departure category) in that study were 1) warm October, 2) cold November and 3) cold October.  So basically this fall like last fall guarantees no matter the outcome, one of these months (if not both if the winter is "normal") will fail.

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Final answer:

 

ITS OUR ANNUAL LOOK TO SEE IF THE PAST CAN HAVE SOME CLUES AS TO HOW

THIS UPCOMING WINTER WILL BE. GIVEN THE RARE COMBO AGAIN OF A WARM

(TOP THIRD) OCTOBER AND A COLDER THAN THE LONG TERM MEDIAN NOVEMBER, WE

HAD TO ASK SOME ARCHAEOLOGISTS FOR ASSISTANCE. WHILE LAST AUTUMN WE

HAD A SIMILAR COMBINATION, THE NON-TROPICAL PACIFIC OCEAN IS IN A

WHOLE DIFFERENT LEAGUE AND FOR BETTER OR WORSE 2012-13 DID NOT MAKE

THE CUT.

 

IN TERMS OF ENSO, THE LATEST CONSENSUS OF ALL DYNAMICAL MODELS FOR A

DECEMBER, JANUARY AND FEBRUARY AVERAGE IS A MR. BLUTARSKY 0.0C. THE

OUTLOOK CONSENSUS LEADING INTO THE SUMMER OF 2014 IS FOR AN EL NINO

TO START DEVELOPING. THERE ARE ALREADY WARMER RELATIVE TO NORMAL

WATERS ALONG THE EQUATORIAL PACIFIC WEST OF THE ENSO 3.4 REGION. FOR

THIS REASON, THE ANALOGS CHOSEN VARIED FROM ENSO NEUTRAL NEGATIVE TO

A WEAK EL NINO. BECAUSE OF THE DIRECTIONALITY, WE ONLY INCLUDED ONE

WEAK LA NINA BECAUSE ITS DEPARTURES SINCE AUGUST WERE SIMILAR TO

THIS YEAR.

 

CLIMATOLOGICALLY SPEAKING SINCE THE WINTER OF 1949-50, THERE HAS

BEEN AN INTERESTING CLIMATOLOGICAL SPLIT WITH ENSO NEUTRAL WINTERS

IN PHILADELPHIA. ENSO NEUTRAL POSITIVE WINTERS HAVE LACKED LARGER

SNOW EVENTS. THERE HAS BEEN ONLY TWO SIX INCH OR GREATER

EVENTS (OUT OF SIX ENSO NEUTRAL POSITIVE WINTERS) SINCE 1950.

COMPARE THIS TO A WEAK EL NINO THAT HAS HAD EIGHT (OUT OF TEN

WINTERS) AND ENSO NEUTRAL NEGATIVE THAT HAS HAD THIRTEEN (OUT OF

FOURTEEN WINTERS). OF LATE SNOW STORMS THAT HAVE AFFECTED OUR AREA

HAVE BEEN MORE WHOPPERS THAN RUN-OF-THE-MILL ONES. OF THE TWENTY-ONE

TEN INCH OR GREATER EVENTS IN PHILADELPHIA SINCE 1950, TWELVE OF

THEM HAVE OCCURRED SINCE THE WINTER OF 1995-96 AND FIVE OF THE LAST

SIX SNOWFALL EVENTS THAT HAVE CROSSED THE SIX INCH THRESHOLD WERE

TEN INCHES OR MORE.

 

LAST WINTER THE OUTLOOK TREND WAS TOWARD EL NINO, BUT THE EASTERN

NON-TROPICAL PACIFIC WAS MORE HOSTILE. TAKING US TO THE REST OF THE

PACIFIC. WARMER THAN NORMAL SEA SURFACE TEMPERATURE DEPARTURES HAVE

MADE IT INTO THE EASTERN PACIFIC. THE PACIFIC DECADAL OSCILLATION

WHICH WAS STRONGLY NEGATIVE LAST FALL AND WINTER (WHEN THE WARMEST

WATERS WERE CONFINED WEST), IS CLOSER TO NEUTRAL HEADING INTO THIS

WINTER. WE HAVE ALREADY SEEN THE EFFECTS OF THIS IN NOVEMBER AS THE

EASTERN PACIFIC OSCILLATION TELECONNECTION INDEX HAS BEEN NEGATIVE

(MORE EASTERN PACIFIC RIDGING) AND HAS SET IN MOTION A STRING OF

VERY STRONG HIGH PRESSURE SYSTEMS FROM CANADA INTO THE UNITED STATES.

 

AS FOR TRYING TO OUTLOOK THE NORTH ATLANTIC OSCILLATION WE HAVE

LOOKED AT APPROXIMATELY SEVEN DIFFERENT METHODS THAT HAVE HAD SOME

DEGREE OF SUCCESS IN THE PAST. THE SCOREBOARD FOR THIS WINTER IS

THREE FOR NAO POSITIVE, AND FOUR FOR NAO NEGATIVE. THE MORE

POPULAR ONE (DEFACTO NAO BECAUSE IT IS AN AO OUTLOOK. THE FORMER

NORMALLY FOLLOWS ABOUT 75 PERCENT OF THE TIME) OF LATE HAS BEEN THE

ADVANCE OF SNOW COVERAGE IN SIBERIA IN OCTOBER. FROM THE RUTGERS WEB

SITE, WE SAW THAT SNOW COVERAGE ADVANCED QUICKLY IN SEPTEMBER AND THE

FIRST HALF OF OCTOBER, BUT THEN SLOWED IN THE SECOND HALF OF

OCTOBER. IN SPITE OF THIS, EURASIAN SNOW COVERAGE FOR THE MONTH OF

OCTOBER WAS THE GREATEST SINCE 2002. LOCALLY WE HAVE FOUND ITS A

BETTER INDICATOR OF SNOW THAN TEMPERATURES. SEASONAL SNOWFALL

STATISTICALLY SPEAKING IS NOT A NORMAL DISTRIBUTION, BUT A GAMMA

DISTRIBUTION. THE SNOWY WINTERS SKEW THE AVERAGE HIGHER. THE MOST

LIKELY OUTCOME FOR ANY GIVEN WINTER IS BELOW AVERAGE SNOWFALL.

PHILADELPHIA`S MEDIAN SNOW SINCE 1967 HAS BEEN 17.75".  SINCE

SNOW COVERAGE HAS BEEN MAPPED BY SATELLITE, 33 PERCENT OF ALL WINTERS

HAVE HAD SNOWFALL ABOVE THE CURRENT NORMAL. BUT WHEN EURASIAN SNOW

COVER IS GREATER THAN NORMAL IN OCTOBER, THE PAST PERCENTAGE HAS

INCREASED TO ABOUT 50 PERCENT. THIS DID NOT HELP US LAST WINTER. OF

COURSE IF THE EPO REMAINS STRONGLY NEGATIVE, THE NAO STATUS WILL NOT

MATTER AS MUCH.

 

THIS TAKES US TO OUR FALL TEMPERATURES. OF THE 46 WARMEST WINTERS

IN PHILADELPHIA ON RECORD, HALF OF THEM HAVE OCCURRED AFTER A WARM

OCTOBER. THIS NOVEMBER WILL END RIGHT AROUND 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. OUR

COLLEAGUE FROM ACROSS THE AISLE USED TO USE OCTOBER MINS AND

NOVEMBER MAXES (THAT EXPLAINED ABOUT 50% OF THE VARIANCE) FOR HIS

WINTER OUTLOOK. IN HIS STUDY, THESE TWO MONTHS WOULD NEARLY CANCEL

EACH OTHER OUT.

 

SO THE YEARS IN THIS ANALOG MAY LOOK FAMILIAR, SOME WERE REPEATS

FROM LAST WINTER`S OUTLOOK.  OF THESE SEVEN, THREE WERE ENSO NEUTRAL

NEGATIVE, TWO WERE ENSO NEUTRAL POSITIVE, ONE WAS A WEAK EL NINO AND

ONE WAS A WEAK LA NINA. THERE WERE ABOUT 10 OTHER CANDIDATES, BUT

WE REMOVED ANY THAT HAD UNSEASONABLY WARM OR COLD DECEMBERS. AT THIS

JUNCTURE NEITHER EXTREME APPEARS LIKELY.

 

SO HERE ARE OUR LUCKY SEVEN ANALOGS FOR THIS UPCOMING WINTER FOR

PHILADELPHIA. THEIR MILEAGE MAY VARY:

 

 

SEASON         DEC      JAN      FEB    WINTER    SEASONAL   WINTER

               AVG      AVG      AVG      AVG     SNOWFALL*  PCPN

 

1882-3         36.2     30.6     37.0     34.6       N/A    11.14

1914-5         33.3     36.6     38.8     36.2       32.3   19.64

1924-5         36.2     31.8     42.2     36.7       12.1    8.52

1941-2         38.3     30.5     30.8     33.2       10.3    9.24

1951-2         38.7     37.3     38.2     38.1       16.2    7.58

1954-5         36.0     32.6     36.1     34.9       12.1    5.60

1959-0         38.2     34.2     35.4     35.9       21.8   10.17

 

AVG            36.7     33.4     36.9     35.7       17.5   10.27

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 EITHER WETTER OR

DRIER THAN NORMAL.

 

WE WANT TO WISH EVERYONE A VERY HAPPY THANKSGIVING AND MAY

THIS WINTER LIVE UP TO YOUR EXPECTATIONS.

 

post-623-0-87768500-1385404011_thumb.png

 

post-623-0-85725700-1385404013_thumb.png

 

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Our products still go out with all caps, I'm not shouting at anyone.

nice read Tony...I came up with these analogs with a mild October and cold November...I'm using NYC temps...1947 and 1995 are on the list but so is 2007-08...I'll sign up for 1959-60 in a heart beat even though January and February was lacking in snow and cold....

1920...

1947...

1955...

1959...

1971...

1995...

2007...

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nice read Tony...I came up with these analogs with a mild October and cold November...I'm using NYC temps...1947 and 1995 are on the list but so is 2007-08...I'll sign up for 1959-60 in a heart beat even though January and February was lacking in snow and cold....

1920...

1947...

1955...

1959...

1971...

1995...

2007...

Uncle,

 

I had about 16 or 17 candidates and what my WAG December was going to look like (not extreme in either direction)  I saw 1947 and 1995 on my radar too, but those Decembers looked too cold and I believe today's 63 or 64 solidifies "a normal" third November for PHL.  On the other end same reason I chucked 1971 and 2012, their Decembers looked too warm.  My research was solely based on temps, so the snow is kind of a tag along. Only enso states I feel confident about snow are the extremes and strong ninos only after December is done.

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