What caused the Tri-State Tornado?

The Tri-State tornado was most likely an F5.

The Tri-State tornado was the deadliest, fastest moving, farthest traveling, and possibly the longest-lived tornado in United States history. It occurred on March 18, 1925 traveling 219 miles across...

No. The Tri-State Tornado occurred in 1925. There were no efforts to predict tornadoes until the 1940s.

March 18, 1925.

The tri-state tornado formed just the way most tornadoes form: First, a condition called wind shear, in which the speed or direction of the wind changes with altitude. If the shear is strong enough...