CONTEST STATUS - Last update: THU ... 20-APR-17 @ 9:40 PM EDT

Winter '17 / '18 - Snowfall Forecast Contests

19th Annual 'Regular Season'

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17th Annual 'Season-total'

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Winter '16 / '17 - Snowfall Forecast Contests
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18th Annual 'Regular Season'
FINAL results here
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16th Annual 'Season-total'
FINAL results here

Saturday, November 15, 2008

Arctic Oscillation - October '08

CPC posted OCT/s Arctic Oscillation (AO) index recently and it/s up...WAY-T-F up.

OCT came in @ a monster +1.676...the 1st positive value since MAR '08.

It/s only one data point but an important one b/c stratospheric and tropospheric circulations tend to be coupled during winter.

The AO tends to be in its negative phase (weak...warm vortex) when the QBO is negative (easterly). A -AO favors arctic outbreaks over the eastern CONUS; whereas...+AO and QBO-W are associated with a strong...cold PV.

+AO is famous for hording the coldest air over hi-latitudes.
No cold...arctic air => weak baroclinicity.
Weak baroclinicity => less cyclogenesis.
Less cyclogenesis => fewer storms.
Fewer storms => less chance of snow from migratory cyclones.

Time to fold up the tents and go home?

There/s no doubt QBO will be positive (westerly) for most of the '08 / '09 winter...until @ least late FEB / early MAR...which suggests D-J-F...as a whole...might not-be-so-cold-'n-wintry after all.

Best AO analog years using a 'least-squares' method: '95 /'96...'73 / '74...'54 / '55...'75 / '76...and '72 / '73.



R² value is down-right putrid (0.385) for 1st-choice analog year and they go down hill from there. None of the 'best' AO years match up well with 'best' QBO years...so there/s little-to-no confidence the AO analogs offer much insight this go 'round.

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