The tornado warning sirens are activated by an emergency dispatch center located in Glendale Heights. When a tornado warning is issued, the sirens are activated to alert the public that a tornado has either been sighted by a trained spotter or that the National Weather Service has indicated one on the radar. You are to take cover immediately in a basement or center room with no windows in your house. Please do not call the Police or Fire Stations as the personnel on duty become very busy at this time. Turn on an AM radio or television for weather updates and wait for an all-clear to be reported. Sirens are tested on the first Tuesday of each month.