Severe Thunderstorm

A thunderstorm is an atmospheric disturbance that involves lightning and thunder. It may be accompanied by torrential rain, hail or high winds.

A severe thunderstorm can cause flooding, fires, power failures and electrocution, and result in serious damage.

Take shelter as soon as you hear thunder

Taking shelter as soon as you hear thunder remains the safest thing to do.

To determine the distance separating you from the thunderstorm, count the seconds between the flash of lightning and the thunderclap. One second represents approximately 300 metres. For example, if five seconds elapse between the lightning and the thunder, the thunderstorm is about 1,500 metres (1.5 kilometre) from where you are. You must take shelter if the thunderstorm is less than 10 kilometres away.

Follow safety rules

Follow the safety rules wherever you may be. In the case of severe thunderstorms forecast, follow the instructions provided by the authorities.

Indoors

  • Disconnect electrical devices;
  • Close doors and windows securely;
  • Find shelter in a room at the centre of the building, as lightning can go through outside walls, windows and doors;
  • Stay away from pipes and objects that conduct electricity, such as cooking stoves and showers;
  • Do not use the television or the computer;
  • Use battery-powered devices, if possible;
  • Make calls using a wireless phone or a cell phone if you have one; otherwise, use your stationary phone strictly for emergencies; and
  • Wait for the calm to return before leaving your shelter.

In a vehicle

A vehicle with a hard-topped roof (not a convertible) can serve as shelter and protect you from lightning. It is preferable not to drive during the thunderstorm and to stay far away from power lines. If a power line falls on your vehicle, remain inside the vehicle and wait for help.

Outdoors

If you are outdoors during a thunderstorm, the following advice will enable you to reduce the risks related to lightning:

  • Seek shelter in the lowest area that you can find, for example a ditch;
  • Squat down;
  • Put your head against your knees and cover it with your arms;
  • If possible, put insulating material such as a plastic bag between the ground and yourself; and
  • Be ready to move in the event of flash flooding.

Stay away from:

  • Trees;
  • Telephone poles;
  • Power lines;
  • Objects that conduct electricity, such as motorcycles, lawnmowers, golf clubs or umbrellas;
  • Water; and
  • Hills or any elevated places in a open area.

If you are in the woods, seek shelter under a thick growth of small trees or bushes.

If you are in a boat, head for shore immediately.

Source and reference for further information: Urgence Québec – Severe thunderstorms

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