Winter '09 / '10 - WSI - December Update 2

Dr. Todd Crawford - WSI seasonal forecaster:

""The combination of the current El Niño event, cold north Pacific, and weakened stratospheric vortex are favorable for a continuation of widespread below-normal temperatures across the US for the upcoming season"...

""There may be a relaxation of the current cold pattern in the Northeast during January, followed by a return to more consistent cold in February and March."

"In January, WSI predicts regional temperature anomalies as follows:
Northeast - Warmer than normal, except PA/NJ/DE

"In February, WSI sees the monthly breakdown as:
Northeast - Colder than normal

"In March, WSI forecasts:
Northeast - Colder than normal"

More...

The stratospheric vortex began to weaken and split late last month continuing into early DEC; however...the two PV circulations have since merged and the upper level anticyclone has dissipated.  The effects of the weakened PV took about three weeks to reach the bottom of the troposphere...as evidenced by near-record low AO index.

Today/s 10 mb geo-potential height / air temperature analysis (courtesy U of WY) shows a strong... consolidated PV centered near the pole.