Oklahoma is THE tornado state #1! It is the state that gets the most tornadoes per square mile and is home to some of the most powerful tornadoes that have ever struck the world, with El Reno 2013 being the record holder. It has had some devastating EF-5 tornadoes in Oklahoma City/Moore. Many tour companies have their bases in Oklahoma, many chasers live here and the Storm Prediction Center is based out of Norman, OK. If you chase storms, this is most often where you start.
The best storm season in Oklahoma is typically mid April to early/mid May (in terms of historical tornado frequency) but Oklahoma is not necessarily the best State to see tornadoes. The State has its fair share of hills, trees and metropolitan areas in the Eastern parts that makes it difficult to chase and see storms there.
Oklahoma is the most common state to have storm chasing tours departing from and is also among the best states to go chasing in on a specific day as there are many tour companies and tour guides that are based in Oklahoma. In other words, if you want to go chasing on any given day – chances are probably the best you will be able to do so in Oklahoma. In Oklahoma all storm chasing tours are based out of either Oklahoma City or Tulsa.
Storm chasing is, by its nature, not geographically set: you go where the storms are. Even if you start a chase in Oklahoma you can end up in neighboring states while chasing. If you specifically want to chase a setup in Oklahoma or if you would like to chase the storms that exist in Oklahoma on a specific day your best option is to try a Private Tour.
You will have to ask around among the tours in the list linked above to see who can help you out with a storm chasing tour in Oklahoma. A good idea is to ask any of the tour companies listed above as this typically means they can easily do a tour from that city.