The outdoor sirens used to alert St. Louis-area residents about tornadoes will also be used to warn about the threat of destructive thunderstorms.
Destructive thunderstorms, which are rare, produce wind speeds over 80 mph and the possibility of baseball-size hail, and pose a major threat to buildings, trees and property. Only one destructive thunderstorm has hit St. Louis since 2012.
The new warning system went into effect earlier this month after the National Weather Service adopted a three-tiered system by which storms are classified as base, considerable or destructive depending on wind speed and type of precipitation.
When the National Weather Service issues a destructive storm warning, the St. Louis sirens will sound and smartphone users will get an alert, said Sarah Russell, commissioner of the city’s Emergency Management Agency.
Emergency managers from St. Louis, St. Charles and St. Clair counties have all expanded the use of the sirens to include destructive thunderstorms.
The purpose of expanding the warning system is “to differentiate a typical thunderstorm or a lower end severe storm from those that are higher impact ... that would be of a magnitude that would cause much greater damage and a potential loss of life,” said Jared Maples, a meteorologist with the National Weather Service in St. Louis.
Maples added that destructive thunderstorms can cause damage similar to a weak tornado.
If a destructive thunderstorm should strike, Maples advises to “put as much of a buffer between yourself and the outside environment. React the same way you would in a tornado warning. Get yourself to an interior room — shelter that’s sturdy.”
The adoption of the three-tiered system by the National Weather Service will aid the public and broadcast meteorologists in making a quick determination about the severity of an impending storm, Maples said.
“They can look at that information and assess it much more quickly than some of our older products,” Maples said.
The text alerts and use of the warning sirens will be issued in addition to the NotifySTL alerts residents already receive when there’s a threat of a major thunderstorm.