CONTEST STATUS - Updated: SAT ... 18-JAN-20 @ 1:15 PM EST

Winter '19 / '20 - Snowfall Forecast Contests
21st Annual 'Snow Storm' Snowfall Forecast Contest

Snow Storm #2
Synoptiscope in VCP32

Snow Storm #1 (01-DEC-19)
FINAL Results here

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19th Annual 'Season-total' Snowfall Forecast Contest
Deadline for entries has passed
Verification period: 01-DEC-19 through 31-MAR-20
The Forecasts here

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Winter '18 / '19 - Snowfall Forecast Contests
20th Annual 'Snow Storm' Snowfall Forecast Contest
FINAL Results here

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18th Annual 'Season-total' Snowfall Forecast Contest
FINAL Results here
Forecaster verification table here

Wednesday, December 11, 2019

Winter '19 / '20 - Arctic Oscillation (AO): Leading Analogs' 5H and 2mT Composite Anomalies ... as of NOV-19

NOV-19 AO:  -1.193
Same analog years as those associated with AO/s OCT-19 analysis but with a shuffled ranking.

Winter / AVG AO
97-98 / -0.778
58-59 / -1.579
14-15 / 0.849
54-55 / -0.717
53-54 / 0.082
Weighted AO Analogs for Winter '19 / '20:  5H GPHa (l) & 2mTa (r)
- Negative 5H GPHa over Gulf of Alaska & Positive 5H GPHa INVOF Hawaii ==> EPO > 0
- Overall North American pattern mimics Tropic/Northern Hemisphere's (TNH) negative phase often associated with +ENSO.
- Negative TNH ==> 1)  stronger than normal Pacific jet farther south of its normal axis and 2) well above normal temperatures in eastern North America.
- Active sub-tropical jet
- Positive GPHa over eastern Canada would 1) advect cP flow from hi-latitude snow fields into the eastern U.S. and 2) weaken the Hudson LOW.

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At the 95% confidence level ... the Chi-square 'Test of Independence' shows the negative state of NOV/s AO and the average AO state for the ensuing D-J-F period are not independent.  They are related and have predictive value.

Over the AO/s 69 year period-of-record ... the data show when NOV/s AO is negative ... there's a 71% chance the winter/s average AO will be also negative.

The present analog years add weight to the Chi-square analysis indicating AO/s average state this winter will be negative.

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Key
5H - 500 mb
2mTa - 2 meter temperature anomaly
GPHa - geopotential height anomaly
EPO - Eastern Pacific oscillation
cP - continental Polar air mass
INVOF - in the vicinity of

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