• Listen for the JMU Lightning Detection System audible air horn alarms:
  • SINGLE 15-second air horn blast - RED ALERT
  • THREE 5-second air horn blasts - ALL CLEAR
• Seek shelter inside a building until notified by University officials that it is safe to leave.

JMU Lightning Prediction System – A lightning prediction system using audible air horn blasts to warn
of the imminent possibility of lightning strikes within 8 miles of campus

Recommendations Regarding Outdoor Events Regarding Lightning

Current recommendation is to clear fields and events when lightning is 8 miles away.  This allows ample time for persons to enter safe locations and be fully off of fields. The flash-to-bang method is the easiest and most convenient way to estimate how far away lightning is occurring. Thunder always accompanies lightning, even though its audible range can be diminished because of background noise in the immediate environment and its distance to the observer. To use the flash-to-bang method, count the seconds from the time the lightning is sighted to when the clap of thunder is heard. Divide this number by five to obtain how many miles away the lightning is occurring.

The existence of blue sky and the absence of rain are not protection from lightning. Lightning can, and does, strike as far as 10 miles away from the rain shaft. It does not have to be raining for lightning to strike.

When considering resumption of a game or other outdoor activity or function, best practice recommends that everyone ideally should wait at least 30 minutes after the last flash of lightning or sound of thunder before returning to the field of activity.