Outdoor Warning Siren System
The new Polygon-activated siren system was successfully tested August 28-30, 2018. Because of the successes of the testing, the system went live Friday August 31, 2018.
From now on, if you hear a siren during severe weather, it means you are within the path of the rotating storm, and you should seek shelter immediately inside a sturdy structure on the lowest level and most central part of the building.
In these two images, you can see the red outlined area, known as a storm-specific polygon, which indicates the tornado warning. Prior to 2018, we would be required to sound all 254 sirens throughout Jefferson County for this warning. Today, we would only sound the approximately 15 sirens located in Jefferson County's portions of Helena, Hoover and Bessemer, because those are the only areas currently in danger.
The Outdoor Warning Siren System is one of the most public-facing activities our agency is known for, however, it is one we wish for the public to rely on the least. We have 254 active sirens throughout Jefferson County. The Outdoor Warning Siren (not just for tornado warnings) is an audible warning system designed to inform the public, who are outdoors at the time, of impending or ongoing danger. They are based on 1950's era technology.
During an emergency, our sirens will sound with a steady tone for three minutes. If you hear the sirens sounding, and it's not on our monthly test day (1st Wednesday of the month at 10am), we want you to go inside and locate your news sources (phone apps, TV, radio, etc) to get more information about the threat, as well as when the "all clear" is to be given.
Sirens typically have a maximum audible range of 1.5 miles on a clear, calm day with no obstructions between you and the siren. Factor in trees, wind, rain, hail, walls of your house or building, and TV, and it can be very difficult to hear a siren sounding. And if you're asleep, it likely will not to wake you. Additionally, they are electromechanical devices, which means they are prone to a multitude of failures.
While our office, the cities and county continue to maintain the sirens to the best of our ability, we want you to remember this: they are one tool for your warning and notification toolbox, and there should be many tools in that toolbox!
In August of 2018, our siren system was upgraded to incorporate polygon-specific activations, based on the National Weather Service's storm-specific warning system. This means that the sirens no longer activate county-wide during a tornado warning, but will only activate the sirens located within the actual warning area!!!! This is a critically important change to the way you receive and comprehend warning information. If you hear the sirens during a severe weather event, you are within the storm's path! Take cover immediately, and tune into local news reports for more information.