Here we are in Mid-May, entering the peak of the tornado season and so far we've hardly seen a spring thunderstorm, let alone a severe one. The lack of activity is tied to two key factors, moisture and cold air.

Strong thunderstorms thrive on instability. Warm air and moisture provide that fuel and so far that combination has been non-existent and so has the severe weather season. These are the temperature departures over the past 120 days which bares out the fact warm air has been missing from the severe weather equation over tornado alley.

These are the tornado watches issued so far this year.

Compare that to those of last year, also a fairly quiet year from Iowa west. This severe weather "drought" has been going on for a couple of seasons over the traditional tornado belt of the central U.S.