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, February 18, 2007

Big Changes @ High Latitudes


The ECMWF/s 12z forecast from Friday shows an atmosphere quite different than the one observed all winter. The deep layer flow near the pole for much of the winter has been westerly except for the past few weeks when the weather turned bitterly cold in the E.


The ECMWF progs show a troposphere and stratosphere bathed in easterlies and the stratosphere warmed 20°C by February 24.

A warm stratosphere comes about when the troposphere is cold (lower heights in the troposphere means lower and therefore warmer heights in the stratosphere).


Deep easterlies mean the pole is dominated by HIGH pressure. Easterlies weaken the polar vortex (PV) or shift its position and leads to an increase in general storminess in the mid-latitudes.

Broad HIGH pressure at the poles is observed during the negative phases of the Northern Atlantic (NAO) and Arctic oscillations (AO). The negative phase favors arctic outbreaks in the E CONUS.

Taken together...deep easterlies...-AO...and -NAO suggest a good potential for additional winter wx along the EC toward the end of the month.

Click on cross-section images to animate.

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