Since 1950, tornadoes in South Dakota have killed 50 people and injured 1,191 more.
They can happen most of the year in South Dakota: as early in the spring as March 29, as one did in 1982; and as late in the fall as Oct. 29, as happened in 1996.
This week, April 22-26, has been declared Severe Weather Awareness Week in South Dakota. A statewide tornado drill is set for Wednesday, April 24. The test watch is scheduled for 10 a.m. CDT (9 a.m. MDT) with the warning to be issued at 10:15 a.m. CDT (9:15 a.m. MDT). Severe weather sirens will be sounded in most of the communities across South Dakota. State officials sent out a reminder to the public that it will be only a test; unless otherwise announced.
There hasn’t been a tornado reported this year in the state, yet, and usually they don’t happen this early in the year. But Tina Titze, director of the South Dakota Office of Emergency Management, said now is the best time to plan what to do when severe thunderstorms or tornadoes hit.
“In just the last few weeks, we have seen the impact winter storms can have. Spring and summer weather is no different,” Titze said. “Families should discuss what to do if severe weather happens. Where do you go if you are outside when a thunderstorm begins? What do you do if a tornado warning is issued? These are important things to be ready for.”
Tornadoes are rated on the Enhanced Fujita Scale according to wind speed. Meteorologists are hard pressed to get accurate wind measurements of a storm in progress. Tornadoes can appear and disappear quickly, often taking unpredictable paths along the ground. Some weather stations have been damaged by the tornadoes they are trying to measure. As a fallback measurement, wind speed is often rated from the aftermath of the storm, with what kind of trees survived or were taken, and the extent of other damage. This information, and more, is available from the National Weather Service.
The most powerful tornadoes are also the rarest, but do the most harm.
EF5 (the strongest) and EF4 tornadoes represent only about one percent of all tornadoes recorded nationwide, but they cause two-thirds of the deaths attributed to tornadoes each year. Due to people not heeding warnings as seriously as they should, the National Weather Service now uses more graphic language in its tornado bulletins, replacing dry estimates of wind speed and movement with the extent of damage the tornado can create.
An EF5 tornado has sustained winds of 200-plus miles per hour. There have been only two such tornadoes officially recorded in South Dakota since 1950. The one in Tripp County on May 8, 1965, caused only one human injury. The other, on July 28, last year, in Harding County, caused no human injuries, but did lift an old Case tractor from a rancher’s yard and took it into Montana, leaving it in pieces scattered over a long path.
An EF4 tornado has sustained winds of 165-200 mph. Only eight of these have been officially recorded in the state since 1950. These have caused seven deaths and 157 injuries. There was one in Yankton County on June 7, 1965. Another tornado, on the same date, in Turner County, resulted in one death. Harding County saw one on July 7, 1969.
The infamous Spencer tornado, which destroyed much of that town in McCook County on May 30, 1998, killed six people and injured 150.
An EF4 tornado hit near Barnard in Brown County on June 23, 2002. Four people were injured in a tornado touching down near Esmond in Kingsbury County on June 24, 2003. Boudle in Edmund County saw an EF4 tornado on May 22, 2010.The community of Lane in Jerauld County had two people injured in a June 18, 2014, tornado.
South Dakota has experienced 60 EF3 tornadoes since 1950. With sustained winds of 135-165 mph, these are still deadly and have resulted in a total of 11 deaths and 261 injuries in the state.
Weaker yet at 110-135 mph wind is the far more frequent EF2 class of tornado. With 306 of this ranking on record for South Dakota, these storms are responsible for 16 deaths and 396 injuries.
There have been 563 EF1 tornadoes, which have 85-110 sustained wind speeds. These caused 16 deaths and 376 injuries. The last EF1 that caused injuries was on May 10, 2015. It grazed Delmont in Douglas County, which caused nine injuries. On June 4, 1999, an EFI tornado slammed into Slim Butte in Shannon County, killing one and injuring 54.
There is a class EF0 ranking for tornadoes, which includes those with sustained wind speeds of 65-85 mph. Counting all tornadoes, there have been 1,627 tornadoes in South Dakota since 1950, with a total death count of 50. That averages out to almost 24 tornadoes per year over 69 years from 1950-2018.