Tuesday, December 27, 2011

Winter '11 / '12 - Sudden Stratospheric Warming Watch - Update 2

It's official!

A 'minor' stratospheric warming...no longer a figment of NWP/s imagination...was observed at 10 mb by the Japanese Meteorological Agency (JMA) for the seven-day period ending 25-DEC-11.

A minor warming event is defined as an observed 25°C temperature increase over "... a week or less at any stratospheric level in any area of winter time hemisphere. The polar vortex is not broken down and the wind reversal from westerly...to easterly...is less extensive." ¹

The heavy red shadings denote the 25°C threshold.
The image is approximately oriented north-south along 140°E longitude.
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Previous update here.

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