On the sea, it would be called a hurricane, but here it is a cyclone. You can see the centre over Iowa.
With the mimic map, you can see it was caused by a Pacific plume slashing down on us and sucking up the Gulf warm air which would normally just stay there. This shows the last 72 hours.
Now, the warmies are going to say this is climate change, but this is due as much to the tremendous cold air coming down with the upper plumes, as to the warm air. If there is a severe difference, then we get a bomb.
ps. the bomb has gone through Toronto, now it's cold. Nlfd has ice conditions from 30 years ago.