06/18/2026
Information from Decatur County EMA on how tornado sirens are used and when they are activated.
How do all Decatur County Tornado Sirens Work?
1. Tornado sirens are only meant to be heard by people outside. They were not designed to be heard inside homes.
2. Decatur County’s sirens are automatically polygon activated. That means when the National Weather Service (NWS) issues a polygon (a computerized shape file) the computer system picks this up, sees what sirens are covered by that polygon and activates the necessary sirens. The exception to this rule is if one siren is activated in the City of Greensburg, all Greensburg sirens activate out of caution to the public.
3. Decatur County sirens only activate for three reasons:
a. NWS issued Tornado Warning
b. NWS issued Tornado Emergency
c. NWS issued Potentially Destructive Storm (one criteria for this is baseball size hail that poses a threat to life).
4. There is no longer the condition of Tornado Watch and Severe Thunderstorm Warning will cause the sirens to activate. That method has not been used in quite a while.
5. If the automatic system should fail, there are redundancies in place for the sake of public safety. First, 911 Dispatch has the capability to set the sirens off. However, if that activation has to be used they can only set off the “All Call” switch which will
activate all sirens county wide.
6. Second redundancy is a manual switch activation. Again, this is an “All Call” that sets off all sirens.
7. Third redundancy is the signal company we are contracted with can do a manual activation. Depending on the issue and circumstance, this could be an “All Call” activation.
Last night (6/17/2026 into the early morning of 6/18/2026) there was a software failure on the siren system. This required the “All Call” redundancies to be activated. By doing this, all Decatur County sirens were activated. It was in fact for NWS issued Tornado Warnings and activating through the specified time frame for the warnings. However, if the system had activated normally and automatically, it would only have set o sirens in the Westport area.
I hope this clears up some confusion about how our sirens work.