When a devastating tornado touched down inMoore, Oklahoma on May 20, 2013 locals had 16 minutes to get to safety before the mile wide EF4 hit. Even that seemingly short warning is enough to save a ton of lives.
The Oklahoma City siren system, a network of 181 Whelen emergency warning sirens, was state-of-the-art when it went online in April, 2002 replacing the cold war-era sirens that covered only the most densely populated parts of the city. The siren equipment, called a mass notification system, comprises hardware from Whelen Engineering of the USA linked via radio telemetry. The sirens are spread across three counties around Oklahoma City, including the county Moore is located in. Moore itself has 36 sirens in its Outdoor Warning System many of them near schools: The sirens sound once the National Weather Service issues a tornado warning, and they serve as a signal to turn on a television or radio to get more detailed information about the storm and instructions on how to seek shelter.
Prerecorded voice messages provide information and directions with the public advised to seek shelter in a basement or safe room on the lowest level of the building they are in. Avoiding areas near windows and doors are recommended, and people are not advised to travelling to shelters during a tornado.
Regular test broadcasts ensure that the public is mindful of the threat and that the system is in place.
Silent tests confirm system functionality on a daily basis.