On August 14, 1924, the dealiest and costliest tornadoes ever recorded at the time touched down near Ann Arbor at 4:09 PM. Killing 327 and causing over $900 million (2016 USD, $250 million 1924 USD), the twin tornadoes devastated parts of eastern and central Michigan.
At 4:08 PM, the tornado twin #1 touched down just 13 seconds before tornado twin #2. The weaker twin, this tornado caused the weaker damage, although it still killed 109 and caused $350 million (2016 USD, $95 million 1924 USD) in damages. This tornado was the left side tornado.
At 4:09 PM, 13 seconds after the touchdown of twin tornado #1, twin tornado #2 touched down just in front of the twin tornado #1. Causing the other $550 million (2016 USD, $155 million 1924 USD) and killing 218, twin tornado #2 may have had over 310 mph winds after a recent discovery that a citizens anemometer measuired 312 mph winds. This was the tornado on the right side of the picture.