8 tornadoes confirmed in the Miami Valley as of May 21, 2019.
Recently we saw 11 tornadoes in 2017. El Nino Occurred both years.
El Nino happens when the sea surface temperature is recorded at temperatures above normal.
The warm ocean water typically leads to a more active weather pattern for the southern United States and a Warm and dry pattern for Ohio.
This year is not typical. We are experiencing Meridional Flow. This means the upper levels winds are not moving from east to west. Instead, they oscillate up and down creating troughs and ridges in the jet stream.
This pattern is responsible for temperature swings like we are experiencing now. Today’s high was 63, by Thursday we may be pushing 90 degrees.
In a typical El Nino, the subtropical jet stream will keep warm, moist gulf air from reaching Ohio. Meridional Flow creates the trough allowing a low-pressure system to dip south and then bring the war, moist gulf air up to Ohio, instead of tracking across the southern half of the United States.
Without Meridional Flow we would not be seeing severe thunderstorms in Ohio right now.
In fact, three of the worst tornado outbreaks have occurred during La Nina years. This includes the 1974 Outbreak which produced the devastating F-5 Tornado in Xenia.
Typically the Miami Valley only sees 2-3 tornadoes in a year.