The importance of a cross polar flow and Aleutian ridge in December
Multiple ensemble guidance indicate a major pattern change over the Pacific region. A ridge will builds near Aleutians then poleward into the Bering Strait and the Artic Ocean next week. This will cause cross-polar flow to finally setup over the North America. All the anomalous cold air that is has been over much of Eurasia for the last several weeks with finally see an open gateway into North America. Temperatures departures are forecast to between 10 to 20 below average over parts of the Rockies and Northern and Central Plains over next weeks.