Eastern Michigan University

Environmental Health & Safety

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Severe Thunderstorm

While all thunderstorms are dangerous, the National Weather Service (NWS) considers a thunderstorm severe if it:

  • Produces hail at least three-quarters of an inch in diameter
  • Has winds of 58 miles per hour or stronger
  • Produces a tornado

Thunderstorms generally occur during the warm months. However, they can occur at any time during the year. More people are seriously or fatally injured by lightning from thunderstorms than by any other weather condition.

During a storm, stay informed of weather conditions. Have a portable radio available and listen to the local station (WEMU 89.1 FM) for watches/warning issued for the area. The following watches/warnings may be issued:

  • Thunderstorm Watch: Severe thunderstorms are possible in the area. Watch the sky and stay tuned to WEMU 89.1 FM for additional information. Watches are intended to heighten public awareness and should not be confused with warnings.
  • Thunderstorm Warning: Severe thunderstorms are occurring. Warnings indicate imminent danger to life and property to those in the path of the storm.

During a Thunderstorm Watch

  1. Listen to a National Oceanic and Atmospheric Administration Weather Radio, local radio or television stations for updated information.
  2. Be alert to changing weather conditions.

During a Thunderstorm Warning

If Indoors

  1. During a storm, remain inside and stay away from windows, water faucets, sinks and bathtubs.
  2. Do not use telephones. Unplug computers, televisions and other appliances or equipment that could be damaged by lightning. Electrical energy from a lightning strike can be carried inside on wires and pipes.
  3. Avoid the top floors of buildings and areas with windows or glass. Move into inner hallways, stairwells, restrooms, or other areas that are directly supported and relatively free of windows and glass.
  4. Avoid areas which may be glass enclosed or have a large unsupported roof.
  5. Remain indoors until the warning expires.

If Outdoors

  1. Take shelter in substantial, permanent, enclosed structures, such as reinforced buildings. Sturdy buildings are the safest place to be. Avoid unprotected gazebos, rain or picnic shelters, golf carts, baseball dugouts and bleachers.
  2. If there are no reinforced buildings in sight, take shelter in a car. Keep car windows closed and avoid convertibles.
  3. As a last resort and if no structure is available, go to a low lying, open place away from trees, poles, or metal objects.
  4. Avoid tall structures such as towers, tall trees, fences, telephone lines, and power lines. Lightning strikes the tallest objects in an area.
  5. Stay away from natural lightning rods, such as golf clubs, tractors and bicycles. Lightning is attracted to metal poles and rods.
  6. Have as little contact with the ground as possible. Squat low to the ground. Place your hands on your knees with your head between them. Make yourself the smallest target possible. Do not lie flat on the ground.

If in a Vehicle

  1. Pull safely onto the shoulder of the road and stop, making sure you are away from any trees or other tall objects that could fall on the vehicle. Stay in the car and turn on the emergency flashers until the heavy rains subside.
  2. Avoid contact with metal or conducting surfaces outside or
  3. inside the vehicle. Lightning that strikes nearby can travel through wet ground to your car.Avoid flooded roadways. Look out for flooding at highway dips, bridges, and low areas.

Skywarn Spotters

The National Weather Service Detroit Office offers Skywarn Spotter training to those interested in weather, public safety and community service. Washtenaw County offers classes twice a year to be certified. Please visit the Detroit Weather Service Office page for more information.