A commuter is seen bundled for the cold in Boston last January. Craig F. Walker/The Boston Globe via Getty Images/FILE

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 just a week before 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. Wh

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