(CNN) — High above the North Pole, in a slice of atmosphere rarely noticed and even less understood, a transformation is underway. Over the next 10 days, changes in the stratosphere will upend weather patterns and set the stage for a cold, snowy December across parts of the Northern Hemisphere.

It will mean a dramatic swing in weather for parts of the US that are currently simmering in record heat, and it could begin the week of Thanksgiving.

It could also be one of the earliest significant polar vortex disruptions recorded since the dawn of the satellite era.

Think of the stratospheric polar vortex like a wall of wind, corralling the ultra-cold, Arctic air over the North Pole. When it weakens, cold air spills south into places like the Lower 48, Europe and Asia.

Right now, the air in

See Full Page