Tornadoes
A tornado is a violently rotating column of air extending from a thunderstorm to the ground. The most violent tornadoes are capable of tremendous destruction with wind speeds of 500 km/h. What makes a tornado dangerous is that its energy is concentrated in a small area, perhaps only a hundred meters across. Tornadoes can uproot trees, destroy buildings, and turn harmless objects into deadly missiles.
Manitoba is one of three Canadian provinces that lie at the northern end of “Tornado Alley.” This alley, which starts at the Gulf of Mexico coast, covers most the Great Plains that stretch between the Rocky Mountains in the west to the Appalachians Mountains in the east.
Tornadoes are most probable from May through August, with June and July being the most likely months. On average, 7 to 10 tornadoes occur in Manitoba each year.
WHEN A TORNADO THREATENS
- Take shelter immediately, if available, and preferably in the lower level of a sturdy building.
- Stay away from windows, doors, and exterior walls. Flying glass is extremely dangerous.
- Don't waste time opening windows to keep pressure from building up in the house. It's unlikely to help.
- If you are outdoors with no shelter available, lie flat in a ditch, ravine, or other low-lying area, and shield your head with your arms.
- Don't get caught in a vehicle or mobile home, which the tornado can lift. Take shelter elsewhere. If none is available, even a ditch offers better protection. Choose a location where your vehicle won't be hurled or rolled on top of you. More than half of tornado deaths occur in mobile homes. If you live in a mobile home, it is wise to identify a nearby sturdy shelter in advance, and go to that shelter when a severe storm is approaching.
- Beware of flying debris. Even small objects such as sticks and straw can become lethal missiles.
- In heavy rain, be on the lookout for flash floods.
- When swimming or boating, always head to shore at the first sight of a storm.
- Remember that damaged and weakened structures, fallen debris, downed electrical wires, and gas leaks are potential dangers after a storm has passed.
BEST SHELTER
- In a house, go to the basement and take shelter under a stairway or a sturdy work table in the center of the house.
- In a house with no basement, the safest spot is the ground floor in the center of the house. Small rooms tend to be more structurally sound, so seek shelter in a hallway, small room, closet or bathroom (the plumbing may provide some structural stability). Lying in the bathtub with a mattress on top of you may provide good protection.
- In a vehicle or mobile home, get outside and find other shelter. North American officials still debate whether seeking shelter in a car during a tornado is safe. Some officials advise that if the tornado is weak, a car can offer protection against flying debris and rollovers if the occupants fasten seat belts and keep their heads down. However, there is no way of knowing how strong or violent a tornado is without the proper tools, so the safest strategy is to get out of the vehicle. As a last resort, lie in a ditch or culvert, but be aware of flooding.
- Avoid wide-span buildings, such as barns, auditoriums, shopping centres, and supermarkets with large roofs. Go to a nearby sturdy shelter: proceed to the lower floor, an inside room, restroom or hallway, or get underneath a sturdy piece of furniture.
- At school, seek shelter in small windowless rooms such as a washroom instead of a gymnasium. Avoid areas near high walls or large chimneys which may collapse. In shopping centres, stay out of aisles and away from exterior walls and windows. Do not go to your parked car.
- In high rise buildings, move to lower levels, small interior rooms, or stairwells. Stay away from elevators and windows.