Winter '12 / '13 - Arctic Oscillation: New Record for March



Rockefeller Center - NYC
09-FEB-69
(FEB-69 AO:  -1.325; MAR-69 AO:  -2.084)

 The MAR-13 AO of -3.176 crushes the old record of -2.848 set 51 years ago in 1962.

The last time the March AO went below -1 was in 2006.

The last time the March AO tanked below -2 was in 1984.

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The AO for the preceding meteorological winter (D-J-F) averaged -1.122.

The AO/s 5-year moving average during meteorological winter is -0.909

The AO during meteorological winter has been negative...
....four of the last five seasons (average = -0.413)
...nine of the last 10 seasons (average = -0.368)
...12 of the last 15 seasons (average = -0.255)

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Not that any of these trends are abnormal.
The 5-year moving average was negative during the vast majority of the time between mid-50s to late '80s.  The abnormal 'positive ' period occurred between 1989 and 1996.

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Monthly AO data here.

Winter '12 / '13 - 12th Annual Season-total Forecast Contest: FINAL Results

Donald Rosenfeld FTW!
He was the only forecaster to beat climatology this season.

The 'season-total' snowfall forecast contest/s error statistic is total absolute error.

For each forecast station...the absolute value of (Forecast - Observed) is calculated....then summed.

Forecasts with the lower 'total absolute forecast' errors have more skill than those with higher 'total absolute forecast' errors.

PORN is the 'Period Of Record Normal' or climatology.

Skillful season-total forecasts are those that beat climatology.

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Another big season for SNE...especially BDR at 216% of normal...along with BOS and PVD whose 'normal' snowfall falls inside the interquartile range but this season's 'observed' snowfall pushed them in the upper quartile (>= 75 percentile).

Other over-achievers...albeit less notable...were ACY and RIC b/c their 'normal' season-total snowfalls are in the lower 25th percentile of all forecast stations yet they climbed into the interquartile range this winter.

Biggest 'losers' were stations where the 'normal' snowfall is in the upper quartile of all forecast stations yet did not finish the season in the upper quartile.  This year finds CAR...BTV...and BGM on the 'walk of shame.'

Other 'loser' seasons occurred at PHL and IAD.  Their 'normals' fall in the interquartile range but their season-total snowfall put them in the lower quartile.

GREEN - 75th percentile and above.

RED - 25th percentile and below

WHITE - The interquartile range located between the 25th and 75th percentiles.

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Everyone's forecast has been verified and posted to the Contest/s web site here.

Hope to see y'all back again next winter.

Winter '12 / '13 - 12th Annual 'Season-total' Forecast Contest: MAR Totals

MAR totals were 24% above period-of-record normal.

ACY more than three times normal.

Twelve stations measured at least 100% of nornmal....five of which were at least 200% of normal.

The season-total snowfall to date (D-J-F-M) over the entire forecast area was 7% above normal.

Monthly totals for DEC and JAN here...FEB here.