2003 South Dakota Tornado Pressure Drop the Largest Recorded

The pressure drop ahead of a tornado that destroyed the tiny South Dakota town of Manchester 10 years ago remains the largest ever recorded.

As the half-mile-wide twister approached the prairie community on June 24, 2003, the air pressure dropped 100 millibars in just 12 seconds.

The measurement was documented by storm researcher Tim Samaras, who was killed last month chasing a powerful tornado near El Reno, Okla. The record is noted by the National Weather Service and Guinness World Records.

The Manchester twister was the worst of 67 tornadoes that developed in eastern South Dakota on what became known across the state as “Tornado Tuesday.” No one was killed, but three of the town’s six residents at the time were injured.