Winter '09 / '10 - Early Season Stratospheric Warming

Joe D'Aleo has a post up at ICECAP about an incipient warming event @50 and 30 mb that may herald an early start to winter.

He notes the current spike in temperature above the long-term average and draws upon an historical analog where the Arctic Oscillation (AO) collapsed.

Not much support found for warming in today/s 10 mb height field.  There is a small broad region of -45°C air over the northern Canada and NE Siberia.

Stratospheric forecasts from the ECMWF show a short-lived transient flow reversal on the 21st...but no warming in the height - latitude chart (not shown).  The closest to a bifurcated flow over the pole is projected for today...which the analysis from U of Wyoming indicates did occur.

NCEP GFS forecast offers a decidedly different solution @144 hours (NOV 23) and 240-hours (NOV 27). 

D'Aleo concludes with "(i)f this warming in the stratospheric persists, look for a rapid cooling to begin around Thanksgiving."

More from ICECAP (.pdf)...

50mb time-height cross section courtesy CPC Global Temperature Time Series
10mb planar temperature forecast courtesy CPC Stratospheric Analyses and Forecasts
Zonal wind anomalies courtesy CPC Stratosphere-Troposphere Monitoring