Based on this morning's GFS ensembles: A strong surge of cold air will penetrate from the upper mid west down to the lower mississippi valley on thursday, moving to the east coast by Saturday. A reinforcing shot of quite cold air will move into the upper midwest Sunday, spreading to the east coast by Monday with below nomal temps from the upper midwest to New York and New England persisting through Wednesday. Meanwhile, the southern Rocky Mountain states will really heat up early next week with the warmth creeping east across the deep south thru the week.