Houston Chronicle 12/17/2018 by Jason Samenow
Winter got off to a fast start in the Lower 48 even before it was technically winter. Waves of cold gripped the eastern two-thirds of the U.S. and several winter storms tracked across the region.
Conditions have since eased some but the heart of winter lies ahead. Will cold and snowy conditions return and turn more harsh?
The polar vortex, the roaring river of air winding around the North Pole, holds the cards. What they reveal could be very disturbing and a harbinger of extreme winter weather conditions in the eastern U.S.
Judah Cohen, a climate researcher at Atmospheric Environmental Research, monitors the condition of the vortex, every day checking the latest prediction models for any sign of disturbance. He is concerned about what some models are projecting at the end of December or early January.
When the vortex, perched some 60,000 feet high in the atmosphere is stable, winter conditions over the U.S. and Europe tend to be rather ordinary. Winter is still winter, with the normal mix of storms, cold snaps, and thaws.
But when the vortex is disrupted, an ordinary winter can suddenly turn severe and memorable for an extended duration. "[It] can affect the entire winter," Cohen said in an interview.
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