Major disruption' has caused Arctic polar vortex to slide off North Pole, scientists say

[Admin]

A sudden stratospheric warming event reversed the winds that make up the northern polar vortex on March 9. A new animation shows the vortex also moved away from the Arctic towards Europe.

Major disruption' has caused Arctic polar vortex to slide off North Pole, scientists say : Read more

 

[COLGeek]

"Sudden" and something that happened nearly a month ago don't really mesh well.

 

[Classical Motion]

We use to call it springtime.

 

[Unclear Engineer]

"This switch normally happens each year" and "Last year, a sudden stratospheric warming event hit the polar vortex and reversed its winds in early March".

So, how unusual is this, considering the last 4 decades? Is there some sort of trend over those decades?