Johnson County’s outdoor warning system consists of 190 sirens placed strategically throughout the county as an early warning device to alert citizens to take shelter and seek additional information. While the outdoor warning system can be an effective method of notifying those outdoors, it is only one component of a comprehensive emergency warning system including the use of NOAA weather radios, the Emergency Alert System, and emergency notifications from local media. Through the Project Community Alert program, these radios are available through local Price Choppers.
Designed as an outdoor warning system, the sirens should not be relied upon to provide sufficient warning indoors or in noisy areas. Air conditioning, thunder, wind, rain, and other conditions can cause the sirens not to be heard indoors or outdoors (even if sirens can be heard during tests). Sirens are also subject to lightning strikes and other equipment malfunction. For these reasons, everyone is encouraged to have multiple ways to receive information about severe weather.
The outdoor warning system for Johnson County is tested at 11:00am on the first Wednesday of the month. Tests can be postponed for two primary reasons:
- Extreme cold, freezing rain/drizzle, and/or icing might damage the equipment.
- There is severe weather (or potential severe weather) occurring in the local area and activating the outdoor warning system might cause confusion as to whether the activation is a real event.
If it is determined that the monthly test will be postponed, the test will be rescheduled for the second Wednesday of the month at 11:00am. If it is determined that the monthly test is unable to be performed on the second Wednesday, the test for that month will be canceled. The next test will then be the regularly scheduled test on the first Wednesday of the following month at 11:00am.
In March, the siren test may be performed on the first Wednesday in addition to the activation of the system as part of a statewide tornado drill during Severe Weather Awareness Week and in conjunction with the National Weather Service. These drills are typically conducted on a Tuesday or Thursday (back-up date) afternoon, late enough as not to disrupt the school lunch period.
The cities within the county own and maintain the sirens within their cities. Johnson County Emergency Management has the primary responsibility to activate the sirens throughout the county. In addition, the cities of Lenexa, Olathe, and Overland Park have the capability of activating their own sirens if they so chose.
There are three basic criteria to activate the sirens for tornadoes:
- The National Weather Service issues a Tornado Warning for Johnson County,
- A county trained and certified weather spotter reports a tornado; or
- A tornado is reported by a local public safety official.
Johnson County has the capability of activating all of the sirens at once or by activating one or more of five established siren zones. All sirens are sounded unless the threat is clearly confined to an individual zone (or zones). During a tornado warning, the sirens will be sounded for a three minute duration in ten minute intervals (three minutes on, seven minutes off) for as long as the tornado warning is in effect. There is NO “all-clear” siren.