More investigation finds more tornado records for December 15th

Tornado near Salix. [photo courtesy of Rebecca Irene/KSCJ]

By Pat Powers, KQWC/Radio Iowa
Weather experts are still studying the powerful derecho that hit Iowa two months ago and they’ve determined the wind storm spawned a record number of tornadoes in several categories.

Rod Donavon, a meteorologist at the National Weather Service in Johnston, says that single storm spun off more than five-dozen twisters, a startling number, especially in one day. “We have verified 63 tornadoes across Iowa for the December 15th event, which is actually a daily record of tornadoes for Iowa,” Donavon says. “We’ve been doing a lot of work, checking out anywhere anybody’s had damage. We even used high-resolution satellite data to help track down all of these tornadoes.”

One person in eastern Iowa was killed in the December 15th storms, which caused extensive damage in multiple Iowa counties. Donavon says there’s an unusual coincidence with the two previous dates for single-day tornado records in Iowa.

“Number-two was actually August 31st of 2014 when we had 35 (tornadoes) and I’ll add into that number-three was April 11th of 2001 when we had 28,” Donavon says. “When you combine the previous top two, that actually equals 63, which is the number we had on December 15th.”

Not only did December 15th set a single-day record for tornadoes in Iowa, but it also set a record for the most tornadoes in a month. “Our previous monthly record was 57 from back in May of 2004,” he says. “So it even eclipsed the monthly record.”

The December 15th storm set yet another record for the highest number of E-F-2 tornadoes in a single day — at 21. The storm was the second derecho to hit Iowa in recent years. The first tore across the state on August 10th of 2020.