The severe drought in Illinois may have killed crops and dried up rivers, but it also has kept the tornadoes at bay.

“It’s one of the few benefits we get out of a drought,” state climatologist Jim Angel said.

Fewer tornadoes

Thunderstorms need to form and evolve for tornadoes to happen. Less tornadoes formed this year because the drought caused a lack of moisture necessary to produce thunderstorms, which in turn create tornadoes, NIU staff meteorologist Gilbert Sebenste said.

Angel said the two primary ingredients needed are moisture and some sort of cold or warm front.

Experts may know of the ingredients needed to create a tornado, but they do not know how tornadoes develop.

Unofficially, 16 tornadoes were reported this year in Illinois.

Last year 80 tornadoes were reported in Illinois, 24 of which occurred in northern Illinois. In 2003, a record-setting 120 incidents took place, 18 of them in northern Illinois.

Ninety-nine percent of all tornadoes come from rotating thunderstorms, or supercells, Sebenste said.

However, not all strong thunderstorms create tornadoes.

There are about 100,000 thunderstorms in the United States on average per year, Angel said. On average, about 1,000 tornadoes develop from them.

Jim Allsopp, a meteorologist with the National Weather Service, said Illinois experienced below-normal thunderstorms this year.

Funnel trends

The long-term average of tornadoes in Illinois is 30. However, over the last 10-15 years the number of tornadoes exceeded the average.

Sebenste said the current trend in tornadoes shows an increase because people see and report them. It is estimated about half of tornadoes go unreported because no one sees them.

There is a bigger effort to watch and report tornadoes, Allsopp said,

“The number of severe and violent tornadoes hasn’t changed over the years,” he said.

The weaker tornadoes are responsible for the increase because in the past they were either insignificant or no one noticed them, Allsopp said.