Pattern Resets Back to Default

Drought builds and a battleground of cold and warmer air setting up.

In the long-arc of history, please let it be known that cold air meeting warm air alone does not directly cause tornadoes — case in point this week.

1. The Jet Stream’s Default State

With a weak La Niña, the tendency for a ridge in the west to push the jet stream up and then down over the eastern U.S. is strong — which I call its current default state. As some folks are dealing with tornado damage in Oklahoma, the jet stream is set to deliver a winter blow to the temperatures, dragging cold air south.