The northern branch of the jet stream features a major blocking ridge over Alaska and northwest Canada extending up towards the pole. And a broad trough (polar vortex) over most of Canada extrending southward into most of the northern U.S. This is a cold pattern for most of Canada and the northern U.S. The southern branch of the jet features a migratory trough over the southwest U.S. A west to east flow across the south-central and southeast U.S. And a weak trough over the eastern Gulf of Mexico. Subtropical high pressure is located over the southwest atlantic.