Something unusual may be brewing in the stratosphere, and meteorologists say it could change the course of the winter forecast.
The atmosphere is at a "critical juncture," and what happens in November could be a "fork in the road" for the rest of the winter, said climatologist Judah Cohen, a research scientist at MIT, in an email to USA TODAY.
Weather models are signaling the stratosphere could warm suddenly, possibly causing a counter-intuitive cooling effect at the surface of the planet.
If "a sudden stratospheric warming" event does occur, cold and snow could soon be arriving across much of the nation.
Cohen said the developments will determine how the often-misunderstood polar vortex influences weather in the United States and how cold air from the north will be steered by the La Niña weather pattern.
