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

Sunday, January 15, 2012

Winter '11 / '12 - Sudden Stratospheric Warming Watch - Update 6

The minor warming criterion (25°K increase over seven days at any level in the winter hemisphere) has almost reached the 30 mb level.  A mere two or three degrees to go.


Major warming criteria is on the verge of being breached.
A major warming is defined as "...westerly winds at 60°N and 10 mb...become easterly [...].  A complete disruption of the polar vortex is observed and the vortex will either be split into daughter vortices, or displaced from its normal location over the pole." 


Westerly winds at 85°N and above 10 mb have reversed.


'Complete' distruption is a stretch given the D+10 forecast.  There's more blue (easterly mean zonal wind) in the several panels leading up to D+10; however...the PV is also expected to re-intensify.


...but a displaced 10mb PV is carried in the forecast.


Another important indicator of stratospheric warming is E-P flux.  Apparently...when the flux vector field leans toward the pole...as shown in the analysis between 11-JAN and 13-JAN...stratospheric warming is underway.

Previous update here.

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