The key ingredients that must come together for tornadoes to form have been more plentiful than normal in June, producing more than 130 tornadoes since June 1.
From June 1 to June 20, at least 117 tornadoes had been reported, compared with a three-year average of 106 for the period, according to preliminary numbers from the National Oceanic and Atmospheric Administration. Nearly 18 tornadoes have been reported since June 20, and more severe weather is expected this week.
A tornado struck Johnson County, Indiana, just south of Indianapolis, Sunday afternoon. On June 21, a tornado outbreak in Texas produced a powerful EF-3 twister in Matador that killed four people, injured nine and caused significant damage.
Tornadoes can form anywhere the right ingredients come together, but they most often form in the eastern half of the United States, when dry winds coming in from high over the Rockies meet moisture-rich, low-level winds blowing up from the Gulf of Mexico.
That interaction provides wind shear – an essential ingredient for tornado formation. The other two essential ingredients are lift and instability.
Through June 20, a preliminary total of 913 tornadoes had been reported. The three-year average through June 20 is 721, according to NOAA.
The year started as the busiest on record for January through March, but was ranked fifth-busiest at the end of May after two months of below average activity.
Published
Updated
