Very unusual' start to tornado season

USNews:  Tornado season is only just beginning, but already this year has seen dozens of destructive twisters from Illinois to Texas, where up to 18 might have touched town on Tuesday alone in the Dallas-Fort Worth area.

"We're at just the beginning of a very unusual" tornado season, NBC weather anchor Al Roker said on TODAY.

The numbers show just how unusual: March saw 223 twisters, up from an average of 80 from 1991-2010, according to the National Weather Service. February saw 63, compared to an average of 29; and January saw 97, compared to an average of 35.
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So what's behind the outbreak?

"We've had record heat," weather.com meteorologist Greg Forbes told TODAY, and "that warmth is a big ingredient that provides the instability for the storms."

Last year started off slowly but then saw a record 758 tornadoes in April 2011, noted Roker. "Hopefully we're not on track for that this year."