Expanding area at 10 mb over Siberia (red shading) where the one-week temperature change exceeds 25°C.
10-hPa temperature change in a week in the Northern Hemisphere
Imagery courtesy Tokyo Climate Center, Climate Prediction Division
PROGSThe 12z / 29-DEC-14 ECMWF suggests the 'split-vortices' SSW portion of the current event will peak between 03 / 06-JAN-15 followed by displacement. on D+10.
Deep-layer easterlies depicted on 03-JAN.
Short-lived daughter vortices appear briefly at the 475K level on 06-JAN.