Background
Climate alarmists typically claim that global warming will lead to more stormy weather.  With respect to tornados, the author of this study suggests that using tornado days instead of tornado frequencies "provides a more stable data set which should allow a more accurate analysis of the phenomenon."

What was done
Daoust catalogued daily tornado frequencies for each county of Missouri, USA, for the period 1950-2002, after which he transformed the results into monthly time series of tornado days for each of the state's 115 counties, its six climatic divisions, and the entire state.

What was learned
The tornado-day time series for five of the six climatic divisions of Missouri revealed the presence of positive trends; however, none of these trends was statistically significant.  For the sixth climatic division, on the other hand, the trend was significant; but it was negative.  Most importantly, at the level of the entire state, Daoust reports that "for the last 53 years, no long-term trend in tornado days can be found."

What it means
For this specific part of the planet, there was no long-term trend in tornado days over the last half of the 20th century, in contradiction of the two-part climate-alarmist claim that the globe warmed dramatically over this period and that global warming leads to more severe weather, thus adding to the many other "specific parts of the planet" where several other types of severe weather have also not increased as predicted (see Weather Extremes in our Subject Index).