NOAA's National Centers for Environmental Information
Visit:NCEI U.S. Tornadoes
According to preliminary data from NOAA's Storm Prediction Center, during September, there were 22 preliminary tornado reports. This was less than one-third of the 1991-2010 average of 74 tornadoes for the month of September. In a very quiet month, no tornadoes were reported until September 8th. Of the tornadoes that did form during September, two-thirds of them (15) formed during the second half of the month. Below is some detail regarding the tornado days during September.
September 23 produced the highest number of tornadoes during the month, as seven weak tornadoes were reported across southwestern Minnesota and eastern South Dakota. There were brief tornado touchdowns in Brookings and Deuel counties of South Dakota producing minor impacts. Nobles and Lac qui Parle counties of Minnesota also had very minor tornado impacts. There were no fatalities or injuries reported.
There were also three tornadoes produced on September 26, one in central Iowa and two in northeastern Florida. In east central Iowa, emergency management confirmed there was a brief tornado of unknown intensity citing reports of ground circulation lofting corn above fields. In northeastern Florida, there was a brief, weaker tornado touchdown that occurred in the vicinity of Lake Asbury. A second Florida tornado reported that day was a brief tornado touchdown near Green Cove Springs. There were no fatalities or injuries reported.
Did You Know?
Tornado Count
Final monthly tornado counts are typically less than the preliminary count. This can be due to some phenomena being inaccurately reported as tornadic activity or a single tornado being reported multiple times. Tornado accounts are reported to the local National Weather Service forecast offices who are responsible for going into the field and verifying each tornado reported. This process often takes several months to complete. Once all reports have been investigated, the final count is published by the Storm Prediction Center (SPC).
The Tornado Monthly Climate Reports are written using the preliminary numbers because the final data is not available at the time of production. Historically, for every 100 preliminary tornado reports, at least 65 tornadoes are confirmed. An error bar is depicted on the tornado count graphic representing this uncertainty in the preliminary tornado count.
The following U.S. studies performed by SPC meteorologists offer deeper context and discussion regarding the frequency and distribution of tornado intensity climatologies:
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Edwards, R., H. E. Brooks, and H. Cohn, 2021: Changes in tornado climatology accompanying the Enhanced
Fujita scale. J. Appl. Meteor. Climatol., 60, 1465-1482
DOI: 10.1175/JAMC-D-21-0058.1. - Mccarthy, Daniel & Schaefer, Joseph. (2004). Tornado trends over the past thirty years. paper presented at 14th Conference on Applied Meteorology.