Thor-Guard is the lightning prediction system that has been installed in River Forest. This system detects lightning and the conditions in which lightning can occur. If lightning or the conditions for lightning are detected, the system will warn all residents in the parks and on the playing fields to clear the area and seek shelter.

Thor-Guard Lightning Prediction Systems scientifically predict the probability of a lightning strike, including the very first strike, unlike "detection" or "tracking" systems which provide a notice based upon the actual occurrence of a lightning strike after the fact! The systems measure the strength of the electrostatic field in the air above River Forest and send a warning signal to horns to be located in each of the parks.

	This is a typical lightning prediction sensor that is located at the River Forest library. It covers all of the River Forest Parks.
This is a horn warning system that has been placed in each of the River Forest parks and playing fields. The horns are activated by radio signal from the centrally located sensor.
A Thor-Guard system was installed in Park Ridge, IL in 1996.