What happens when the vortex splits?

_Elsa_

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‘One segment usually moves over Siberia and the other moves over North America. Once that happens, the jet stream in the troposphere over the Atlantic moves to the south. 

Cold Arctic air that’s normally corralled by the jet stream around the pole is then able to go into the middle latitudes on the East coast, in the Midwest and over Western Europe. 

Storms, which ride along the jet stream, move south, too. They don’t necessarily shift immediately: it can take a few weeks for them to organize themselves to respond and catch up to the jet. Storms that would have hit Canada come and hit New York and Chicago instead. 

The polar vortex itself is not new, but it seems to be affecting weather on the surface every year now in a way that it didn’t in recent memory. What changed? 

The term “polar vortex” has been around since the late 1940s. It forms every winter and breaks up in the spring. But for the last 20 years or so, the polar vortex has been very, very disturbed in the middle of winter. Between 1989 and 1998, however, there were no split vortex events in midwinter. And if you look at polar vortex events starting in 1979, when satellite data begins, until now, the vortex either splits or becomes displaced on average only about once every other year. 

We don’t understand what drives the variability of these events from decade to decade, but they’re definitely happening more frequently. ’ (Source)  

Let’s continue - Polar Vortex explained in 2 minutes

Start at the beginning – The year that spring forgot