This is the revised 2011 Spring-Summer Tornado Forecast.
Using a long-range model, the CFS, this forecast is being perfected consistently.
La Nina is expected to persist throughout this tornado season, and that will play quite a factor throughout the summer and spring.
Below is The Weather Centre’s overall outlook for this tornado forecast.
There is a very nice set up of a very dry air mass over the West US. There is also an open Gulf flowing freely into the Central and East US.
These two factors alone are more than sufficient for tornado and severe thunderstorm formation.
Below is the latest humidity average for the US in the month of July, then August using the CFS.
July has the Gulf free and open while the West is extremely dry. August is very similar, but humidity values are higher. Below is The Weather Centre’s Percentage chances for tornadoes.
In summary, the Central Plains and Midwest are under a preliminary threat for tornadoes this spring, summer and fall.