Winter '14 / '15 - Weakening Polar Vortex ==> Sudden Stratospheric Warming: UPDATE 1

The 12z / 24-DEC-14 run of the ECMWF continued its current campaign for a sudden stratospheric warming event come JAN.

Latest progs point to a weakening and splitting of the stratospheric polar vortex (PV) ... a flip in the high-latitude deep-layer tropospheric flow from W-to-E ... and the ginning-up an anti-cyclonic circulation INVOF 90°N ... all of which point to the near-term development of a negative state for the Arctic Oscillation (AO) and all that implies.