The northern branch of the jet stream features a blocking ridge of high pressure across Alaska and northwest Canada. An intense polar vortex over central and eastern Canada. And a blocking ridge over Iceland and Greenland. This is a cold pattern for most of Canada. The southern branch of the jet features a trough over the eastern pacific. A series of weak troughs extending from the interior western U.S. into the central U.S. And a weak ridge along the east coast. Strong subtropical high pressure centered over the western Caribbean dominates the Caribbean, southern Mexico and Central America.