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Photo of Apple Orchard Golf Course Rainbow in cloudy sky over trees

Thor Guard

The Bartlett Park District has a lightning prediction system that consists of sensors measuring electrostatic charges at ground level and in the atmosphere. These electrostatic charges, invisible to the naked eye, build prior to lightning occurrences. When conditions indicate that a lightning occurrence is probable, a signal is sent to two alarm horns and strobe lights located at the Apple Orchard Golf Course Clubhouse and the Bartlett Aquatic Center. The Apple Orchard Community Park, both east and west sides, is included within the system’s range. The system is operational during park hours from late March to mid-November.

The following procedures are to be followed when potentially dangerous weather exists:

Warning Signal

A Warning Signal (one long 15 second horn blast) will sound and strobe lights will activate when a potentially dangerous weather situation is approaching. The strobe lights are mounted on the top of the Aquatic Center and Golf Course Clubhouse. If the strobe lights are activated, a potentially dangerous weather situation exists.


All activities in the park will end immediately and patrons must leave the park. It is recommended that park patrons seek shelter in their cars or a building. Patrons should avoid areas that are higher than the surrounding landscape, they should not use a tree for shelter, and they should keep away from metal objects such as bicycles, golf clubs, umbrellas, etc. All park patrons must wait until the Lightning Prediction System performs an All Clear Signal before returning to the park.

All Clear Signal

The All Clear Signal (three short horn blasts, two seconds apart) will sound, and the strobe lights will deactivate. After the All Clear Signal sounds and the strobe lights deactivate, park patrons may resume their activities.


The Thor Guard System helps assess the conditions. Neither the signal nor the system is intended to guarantee that conditions are safe. If the weather is threatening and no warning signal is heard or seen, use good judgment and clear the field. Do not wait for the warning signal to activate, as the system can malfunction.

Severe Weather/Thor Guard

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