Even though there were major tornado outbreaks in Dallas and the plains this April, so far, there have been fewer total tornadoes this spring that last year. The chart above shows where we stand so far through the first third of May. Clearly, we still have the potential for more spring-like storms, but these numbers are a bit encouraging.
Everyone remembers the catastrophic outbreak at the end of April 2011 which brought the total for that month to a record 758. That was followed by a very active May, which had 326 twisters including the heartbreaking Joplin storm.
So why is this year different? Last year, the jet stream was lower and created a more active storm track. Also, there was winter weather at the end of 2010. Typically, an active storm season occurs when cold and warm air masses collide as winter ends and spring begins. This year, with most of the country enjoying a mild winter, there were fewer occasions for the storms to form. Even so, when the ingredients were right, the storms were very destructive.
The long-range outlook continues to indicate that most of the country will see warmer than normal weather, with only the southeast U.S. experiencing above normal rainfall. It may be that May will be a much quieter month for big tornado-producing storms.