Lightning Policy


To provide safe sports fields for the use and enjoyment of Greater Lewisville Area Soccer Association (GLASA) residents and their guests as well as establish guidelines and procedures for inclement weather.  This policy serves to inform sports field users of the Thor Guard Lightning Prediction and Warning System and describes guidelines to utilize when thunderstorms approach.

Lightning Prediction System

Lightning is a hazard that must be taken seriously by coaches, officials, parents, spectators and participants.  Lightning is a form of electrical discharge between clouds or between a cloud and the ground.  The discharge may take place between two parts of the same cloud, between two clouds or between a cloud and the ground.  Thunder is the sound waves produced by the explosive heating of air in the lightning channel during the return.  The average lightning strike is six miles long (but could strike from 20 miles away resulting in "a bolt from the blue"), reaches 50,000 degrees Fahrenheit (fours times as hot as the sun's surface), and voltage in a cloud-to-ground strike is 100 million to 1 billion volts.  Thunder can only be heard about 12 miles away under quiet outdoor conditions.  Ground-based items such as fences, trees, blades of grass, light poles, bleachers, dugouts and people emit varying degrees of induced electric activity which can act as a lightning rod.

Previously, many people have relied on the "Flash/Bang" technique (the sound of thunder will take five seconds to travel one mile) to measure their distance from lightning.  You must be aware that on average, thunder can only be heard over a distance of only three to four miles.  By the time you hear thunder, you are already well within the reach of a lightning strike.  For this reason the GLASA and our city partners have purchased and installed the Thor Guard Lightning Prediction and Warning System at Chinn Chapel Soccer Complex, Bakersfield Park, Gerault Park, Lake park and Unity Park. This system is designed to predict a lightning strike within a defined geographical region.  Using sensors connected to a computer, the Thor Guard system is able to measure and analyze the electrostatic field in the atmosphere.  It is in this field that lightning originates.  Once the pre-established detection limits are reached, the system activates a series of horns and strobe lights to warn those playing on sports fields to seek shelter immediately.

When the conditions for a lightning strike exist, the Thor Guard system will give a 15-second blast on the horn cluster that can be heard approximately 700 yards away.  At the same time, a yellow strobe visible from most areas of the park will activate and stay on until the danger has passed or at least 10 minutes after the last detection of lightning.  Once the potential for a lightning strike has passed, the system will activate the horns giving the all-clear signal -- three, five second blasts -- and the strobe light will go off.  However, if weather conditions appear unsafe and the system has not sounded the alarm, common sense should be your guide and activities should cease despite the absence of a Thor Guard warning.  Due to the unpredictability of weather patterns, it may be possible for the alarm to sound multiple times within an hour or even sound when there appears to be no danger (i.e. clear skies).  While stopping and restarting athletic activities due to Thor Guard warnings may result in some frustration, it is important to remember that the Thor Guard system warnings must be heeded at all times.  If the Thor Guard system sets off the alarm on a sunny day, it is not malfunctioning.  There is a chance of being struck by lightning if the alarm is not heeded ("a bolt from the blue").  It is worth noting that many of the lightning deaths and injuries that occur each year are from the first lightning strike from an incoming storm or come from the rear of a storm that appears to have passed through an area.

The following lightning policy has been implemented and is enforced by GLASA and our city partners:

  • Stay tuned to local weather forecasts and radar if thunderstorms are predicted.
  • Once the Thor Guard Lightning Prediction and Warning System senses conditions that favor lightning, there is often a flash of lightning in the area within 10 minutes.
  • When the Thor Guard warning is sounded, suspend all practices and games and seek shelter immediately until the all-clear signal is heard.
  • Everyone should immediately seek shelter anytime they believe lightning threatens them, even if the Thor Guard warning has not been sounded.
  • Stay away from metal including fencing, bleachers, flagpoles, dugouts, sheds, and goals.
  • Avoid high places, open areas, overhead wires and power lines, telephones and cellular phones, radios, isolated trees, picnic shelters, golf carts, or any type of standing water.
  • If you are outside, the interior of a car, truck, or bus with a metal roof and the windows closed is relatively safe from lightning. To be safe, do not touch the metal on the inside of the vehicle.
  • If you are outdoors with no shelter available, find a low spot away from trees, bleachers, fences, and other metal structures. Make sure the area is not prone to flooding.
  • If you feel your hair suddenly stand on end, it means you may be a lightning target. Crouch low on the balls of your feet and try not to touch the ground with your knees or hands.
  • Anyone not following these guidelines when the Thor Guard warning is activated and remains outdoors or in an inappropriate area or shelter will do so at their own risk.
  • If park patrons return to the sports fields prior to the all-clear signal from Thor Guard, they do so at their own risk.
  • Once the all-clear signal sounds, activities can proceed.
  • The Thor Guard Lightning Prediction and Warning System will be operable during league practices, games, tournaments, scheduled reservations, and other sanctioned/sponsored Town activities.

The Thor Guard Lightning Prediction and Warning System helps assess the threat for lightning.  Neither the warning 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 sports field immediately.  Do not wait for the warning signal to activate, as the system can malfunction.  While the system is not infallible, common sense should still be followed. The Thor Guard system is an important tool for enhancing the safety of Town sanctioned activities.

Games Policy

As soon as the horn sounds and the yellow light goes on, all games will be immediately stopped.  Players, officials and spectators must leave the fields and seek a shelter for the duration of the threat (cars are strongly suggested as the space around the concession stand is very limited).  Should the referees feel, using their best judgment, that a potential threat is present, they HAVE to authority to stop the games even before the alarm is triggered.

Since there is no way to determine how long the threat will last, the following rules will apply for all games, regardless on who stops them (alarm or referee):

  1. Any game not started (initial kick-off) will be delayed 30 minutes.  Should the system determines that the threat is no longer in place and goes off within 30 minutes, the game can start.  Beyond the 30 minutes timeframe, the game will be considered cancelled and every effort will be made to reschedule it (subject to time constraints and field availability).
  2. Any game being played and stopped BEFORE the second half kick-off will be considered cancelled and every effort will be made to reschedule it (subject to time constraints and field availability).  For the competitive divisions, the score will NOT count and considered INVALID for the standings.
  3. Any game being played and stopped AFTER the second half kick-off will be considered valid and will NOT be rescheduled.  For the competitive divisions, the score will count and considered VALID for the standings.

Just because the skies look relatively clear, a lightning strike can still occur.

Thanks for your cooperation and helping put the safety of our youth first.