December 15 tornado count now at 43 in Iowa, an all-time record

The National Weather Service has confirmed an all-time record number of tornadoes in December 15's outbreak.
Published: Dec. 22, 2021 at 3:33 PM CST
Email This Link
Share on Pinterest
Share on LinkedIn

CEDAR RAPIDS, Iowa (KCRG) - Last Wednesday’s severe weather outbreak in the state of Iowa is now the state’s largest in history, based on preliminary data from the National Weather Service.

While storm surveys and research about the December 15 event is ongoing, National Weather Service offices in Omaha, Sioux Falls, Des Moines, and La Crosse have identified a total of 43 tornadoes from that outbreak. This places it atop the list of all-time tornado outbreaks in the modern era, which extends as far back as 1950.

A list of the tornado outbreak events with the largest number of confirmed tornadoes, according...
A list of the tornado outbreak events with the largest number of confirmed tornadoes, according to the National Weather Service.(KCRG)

The majority of tornadoes took place in central and western Iowa, with only 7 total falling within counties in the KCRG-TV9 viewing area. Three tracks crossed through parts of Howard County, 2 in Floyd County, 2 in Franklin County, and 1 in Chickasaw County.

Tracks of confirmed tornadoes on December 15, 2021. Information is current as of December 22.
Tracks of confirmed tornadoes on December 15, 2021. Information is current as of December 22.(KCRG/tracks via National Weather Service)

Enhanced Fujita Scale ratings, which are based on surveys of the damage tornadoes cause, have been released for 43 tornadoes identified so far. Four did not produce enough clear damage along their path for a rating, classified as EF-U. Three EF-0, 19 EF-1, and 17 EF-2 tornadoes were identified so far.

The 17 tornadoes to rate EF-2 also makes it a record for the number of tornadoes of that strength, or greater, in a single day in Iowa. The previous record was 16 on June 7, 1984. Iowa only averages about 6.25 tornadoes each year of EF-2 strength or greater.

Iowa averages around 48 tornadoes per year, based on data from between 1980 and 2019. During that same time period, only 4 tornadoes took place in the month of December, making this particular storm not only an outlier for any time of year, but an extreme anomaly for December. June and May, in that order, account for most of the tornadoes in the state in an average year.

Prior to this December outbreak, 51 tornadoes had been confirmed by the National Weather Service in the state for 2021, meaning the total for the year as of today is 94.

The most tornadoes during a month in the state were 57 in May 2004, so the current count for this month is behind that by a significant margin. 43 would place December 2021 as 4th most for a month all-time.

Copyright 2021 KCRG. All rights reserved.