Winter '09 / '10 - Pattern Change

NWP has been hinting at a change in the flow regime for some time.  As early DEC draws near...more and more evidence points toward the arrival of winter wx.

ECMWF height-latitude cross-section forecast for 01-DEC depicts deep layer easterlies near the North Pole...supporting the -AO forecast from the GFS shown above.   Note the long period (into week2) where AO remains well-below zero.

Cold pool aloft shown over central Canada in the 100-mb height-field.  Warm stratosphere ==> cold troposphere.

Excellent antecedent conditions for the season/s 1st coastal teaser.  500 mb heights are a little high but with the 'event' still a week away...taking it one step at a time.  Never want the progs looking too good this far out.