Stratospheric Warming Causes Next Week’s U.S. Cold

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The next "polar vortex" emerging next week is in the troposhere caused by stratospheric warming aloft (unlike the last cold burst in early February).

A more conventional causation of the polar vortex next week

Discussion: The polar vortex re-emerges next week to cause another historic cold outbreak to the Great Plains for the arrival of March. This time the causation of the polar vortex is more common. The arctic outbreak of earlier February was caused by reflection of a high altitude polar vortex downward through the atmosphere over southern Canada. This time a more typical emergence of the polar vortex caused by sudden stratospheric warming (Fig. 1) over eastern North America as the cold core of the high latitude polar vortex shifts cross-polar. In the troposphere an intense polar vortex emerges next week over the Great Lakes region (Fig. 2).

Fig. 1: The cold stratosphere over North America during February shifts cross-polar allowing warming of the stratosphere in eastern N. America.

Fig. 2: Where the stratosphere transfers from cold toward much warmer temperatures a polar vortex emerges in the troposphere across the Great Lakes next Tuesday.