Severe weather has been quite different this year compared to 2011. By the end of April the United States had been hit by 630 tornadoes. That compares to just over 1,000 at the same time in 2011. There are at least a few reasons for the difference. First, Pacific Ocean temperatures appear to be changing from a La Nina to El Nino. Second, the clash between hot and cold air has not been as great during this spring season as temperatures remained milder than average in our area. Third, the jet stream has been further north this year compared to last year. A near normal season is expected through the end of this month. Tornado season usually diminishes across our area by late May and June.