Winter '12 / '13 - VCP 32: The Season/s Over

Winter '12/ '13 - Arctic Oscillation: Is December A Leading Indicator?

UPDATE
December AO:  -1.749
Rank:  11th (17th percentile)

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Original post date:  26-DEC-12 @6:31 PM EST

Little doubt DEC/s index will come in negative given the 30-day moving average stands at -1.965.

Does the sign of DEC/s AO have any predictive value?  The sign of NOV/s AO was shown to have predictive value for the sign meteorological winter/s (D-J-F) average AO.

The 2x2 contingency table of DEC/s AO index and JAN/s index shown below suggests there/s a strong association between the two...especially when DEC/s AO is < 0.

Each cell in the table shows the number of years where the sign of the DEC/s AO was associated with the sign of JAN/s AO.



When DEC/s AO is < 0...there/s an 82% chance the JAN/s average AO will also be negative. 

The table/s precision is 74%...where precision is the proportion of negative cases predicted correctly [a / (a + c)].  The probability of a 'false positive' (-AO forecast; + AO observed) is 36%.

Winter '12 / '13 - Arctic Oscillation: Day 31

Not sure what if anything it means but here/s the state of the AO on Day 31 of meteorological winter during its 63 year period-of-record. 

Blue line is the observed AO on 31-DEC.

Red line is a 9-point binomial filter.  The filter removes noise from the signal to highlight trends.

The 31-DEC-12 AO ranks 31th (52th percentile). 

Same idea for AO/s sister...the North Atlantic Oscillation (NAO).

The 31-DEC-12 NAO ranks 53th (84th percentile).

Winter '12 / '13 - Long Range Forecast: Farmer/s Almanac

Two Towers - New York
Alfred Stieglitz
OCT-1911

January 2013
1st-3rd. Showery, then clearing and cold. Wet for Mummers Day Parade in Philadelphia.
4th-7th. Storm sweeps across Pennsylvania and New York with gusty winds and heavy precipitation.
8th-11th. Blustery and colder; snow showers.
12th-15th. Mostly fair.
16th-19th. Wet, then fair and cold.
20th-23rd. Heavy snow (half foot or more) for New England; lighter amounts farther south.
24th-27th. Scattered flurries.
28th-31st. Sharp cold front brings rain and snow showers, then clearing and cold.

February 2013
1st-3rd. Fair.
4th-7th. A sharp cold front brings gusty winds, rain, and snow showers.
8th-11th. Unsettled; light snow and flurries.
12th-15th. Major Northeast snowstorm develops: some accumulations could exceed one foot; strong winds cause considerable blowing of snow.
16th-19th. Lingering snow showers, flurries.
20th-23rd. Blustery and cold.
24th-28th. A major storm over the ocean perhaps brushes the coast with light snow and gusty winds, then turning fair.

More...

Winter '12 / '13 - SOI: December

December/s SOI (Southern Oscillation Index) came in at -6 after three consecutive months where the index went above zero.

A negative SOI is associated with above normal sea surface temperatures (SST) in ENSO Region 3.4 in the tropical Pacific.  Sustained SOI < -8 indicates el Nino.

Weekly SST anomalies from Region 3.4 have been running a tenth or two below normal the past four weeks causing the 12-week moving average to fall to 0.18 (neutral-warm).

SOI image courtesy Commonweath of Australia/s Bureau of Meteorology

ENSO Region image courtesy CPC

Winter '12 / '13 - Storm #2: Final Results

1st - donsutherland1
SUMSQ:	77.41
SUMSQ Z:	-1.049
STP:	13.15	(5)
TAE:	30.45	(1)
AAE:	1.45	(2)
2nd - Brad Yehl
SUMSQ:	78.27
SUMSQ Z:	-1.040
STP:	10.15	(4)
TAE:	31.05	(2)
AAE:	1.29	(1)
3rd - snocat918
SUMSQ:	104.51
SUMSQ Z:	-0.752
STP:	7.55	(3)
TAE:	39.55	(5)
AAE:	1.72	(4)
HM - Donald Rosenfeld
SUMSQ:	112.59
SUMSQ Z:	-0.663
STP:	1.10	(1)
TAE:	40.20	(6)
AAE:	1.83	(6)

SUMSQ: sum of square errors
STP: storm-total precipitation error
TAE: total absolute error
AAE: average absolute error
(number):  category rank

Full forecast verification and summary at the Contest/s home page.

Winter '12 / '13 - Storm #1: Final Results

1st - dryslot
SUMSQ:	112.98
SUMSQ Z:	-0.887
STP:	5.26	(4)
TAE:	39.64	(6)
AAE:	1.80	(5)
2nd - herb@maws
SUMSQ:	119.42
SUMSQ Z:	-0.846
STP:	13.79	(7)
TAE:	36.79	(3)
AAE:	1.75	(3)
3rd - Brad Yehl
SUMSQ:	213.38
SUMSQ Z:	-0.782
STP:	2.65	(3)
TAE:	35.75	(2)
AAE:	1.62	(2)
HM - Donald Rosenfeld
SUMSQ:	140.87
SUMSQ Z:	-0.711
STP:	0.99	(1)
TAE:	33.99	(1)
AAE:	1.55	(1)

SUMSQ: sum of square errors
STP: storm-total precipitation error
TAE: total absolute error
AAE: average absolute error
(number):  category rank

Full forecast verification and summary at the Contest/s web site.

Winter '12 / 13 - Storm #2: Preliminary Verification

Preliminary storm-total snowfalls for Saturday from CDUS41 and CXUS51 bulletins.

Several stations in the data table do not have SN:H2O reported b/c their liquid totals included mixed precipitation.

CON STP of 2.6" at 10:1 is suspect given surrounding amounts and much higher ratios.

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Two new daily records.
SAT...29-DEC-12
BDR - 3.5" (3.1"; 1959)
IAD - 0.9" (0.3"; 1993)

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Please report any errors and drop a link to the correct data in Comments.

Final results and storm summary Monday evening.

Winter '12 / '13 - Storm #2: The Forecasts

Consensus for a southern NE and northern M-A event.

12 forecasters

3 Rookies...two of which issued their 1st forecast for Storm #2.

Welcome Kevinmyattwx and quagmireweathercentral!

Forecaster answer7 is now an Intern.

Forecasts are ranked by their storm-total precipitation (STP).
BLUE ==> 25th percentile.
RED ==> 75th percentile.
STP cells without color are between the 25th and 75th percentile.

Everyone/s station-by-station forecast at the Contest/s web site.

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Slight amplification in the long-wave flow regime suggested by +PNA.  -AO getting the job done again as its sister index the +NAO offers more evidence of how unimportant she is to snowfall on the east coast.

Winter '12 / '13 - Storm 1: Preliminary Verification

Preliminary storm-total snowfalls for Wednesday through Friday from CDUS41 and CXUS51 bulletins.

Several stations in the data table do not have SN:H2O reported b/c their liquid totals included mixed precipitation.

SN:H2O for CON appears low in light of METARs reported only SN.

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Two new daily records.
THU...27-DEC-12
PWM - 11.6" (8.8"; 1894)
CAR - 6.2" (6.2"; 2010)

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Please report any errors and drop a link to the correct data in Comments.

Final results and storm summary Sunday evening.