NOAA's National Centers for Environmental Information
Visit:NCEI U.S. Tornadoes
According to data from NOAA's Storm Prediction Center, during August, there were 119 preliminary tornado reports. This is above the 1991-2010 average of 83 tornadoes for the month of August. Even though the month had an above average number of tornadoes this activity was dispersed throughout the month, as there were only three days with 10 or more tornadoes. These days with the highest count of tornadoes and their impacts are noted below in chronological order.
On August 9 there were 24 tornadoes that impacted eastern North Dakota, northwestern Minnesota, southern Wisconsin and northern Illinois. This day represented the highest count of tornadoes for the month. These were all EF-1 and EF-0 tornadoes other than one EF-2 tornado that caused agriculture damage near Sharon, North Dakota. The other tornadoes caused damage to homes, outbuildings, vehicles and farms. There were no tornado-related fatalities.
August 11 produced 10 tornadoes that occurred across southern Wisconsin, eastern Iowa, southern Michigan and western Ohio. These were a combination of EF-1, EF-0 and EF-U (unknown) tornadoes that produced scattered damage to homes, farmsteads, vegetation and other infrastructure. There were no tornado-related fatalities.
On August 17, there were 14 tornadoes the impacted northeastern Georgia, central South Carolina and western North Carolina. These tornadoes were associated with Tropical Storm Fred, as it moved across the southeastern states producing heavy rainfall and destructive flooding in western North Carolina. The tornadoes that spun off from Fred were all EF-1 and EF-0 that caused scattered areas of damage to homes, businesses, vehicles and other infrastructure. There were no tornado-related fatalities.
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.