Why all the severe storms this year?

Janie asked this question Friday:
This really has nothing to do with your post...but I was wondering...what is your take on all of the tornadoes that have been occurring this Spring? Why so many? Is it just a matter of time before we see them in our area? Has there ever been another era when so many have occurred? Or maybe is this part of a cycle that is occurring? Thanks for your blog. You are the most knowledgeable, easy to understand, weather guy.

It certainly has been an active year and we got into it a little later this year but had a rude awakening Friday night. As of today there have been 257 reported tornadoes and 2613 thunderstorm wind events. So why all the severe weather this year.

Here's my theory, I think we are seeing this pattern because of the strong La Nina pattern which brought a very strong northern jet stream. This unusually strong pattern has carried over into spring. Why is the jet stream so important? Well the winds of the jet stream can cause lift and buoyancy in the lower levels of the atmosphere. We've seen this strong jet stream in play most of the spring with early thunderstorms across the northern Rockies and plays.

Usually we don't see La Nina as a summer time pattern, so look for this effect to lesson over the next couple of weeks. As far as a cooler then normal summer, I don't think we can correlate to the cold winter season.

This week should be interesting, as we could see more severe weather as early as tomorrow afternoon and evening.