Tornadoes

Most tornadoes in Ontario occur in the late afternoons of May through September, often during periods of high temperatures and high humidity.

Wind speeds within a tornado can range from 64 km/h to over 500 km/h. Tornadoes can last minutes or hours.

A number of significant tornadoes in touched down in Lambton County over the years. The most destructive tornado was an F3 tornado that crossed the St. Clair River and struck downtown Sarnia in 1953. Other tornadoes over have impacted Lambton communities over the years including Reece's Corners in 1983 (F3), central Lambton in 2011 (F2), Grand Bend in 2014 (EF1), and Enniskillen in 2019 (EF1).

On average, Ontario experiences approximately 12 tornadoes each year.

Warning Signs of a Tornado

Many times tornadoes form unexpectedly, leaving forecasters no time to issue official warnings and residents no time to take shelter.

However there are conditions that precede a tornado we can all watch for:

• Thunderstorms that grow steadily worse, with heavy rain and extreme thunder and lightning.
• Large hail (hail larger than a nickel is evidence of a strong storm).
• An extremely dark sky, sometimes highlighted by rotating green or yellow clouds. Sometimes wisps of cloud will be seen swirling upward toward a low point in the clouds.
• An eerie calm at the end of a severe storm – the sun might even be visible.
• A rumbling sound like a freight train, or a whistling sound like a jet.
• A “wall of white” coming toward you – many tornadoes are hidden by heavy rain and a funnel might not be visible.

If you observe any of the above warning signs, take cover immediately.

Be aware and prepared: Watches & Warnings

Environment Canada will issue tornado Watches or Warnings when necessary, but tornadoes can form unexpectedly, so a Watch or a Warning may not precede a tornado touchdown.

Know the differences - they are significant - between Watches and Warnings.

When weather conditions look threatening, turn on your battery-powered radio and listen for weather reports or check the Environment Canada Warnings webpage. If your area is advised to take cover, do so immediately.

What to do if a tornado threatens

• Take shelter immediately, preferably in the lowest level of a sturdy building.
• Stay away from windows and exterior doors and walls. Flying glass and debris blown into a building are extremely dangerous.
• Do not spend valuable time opening windows to prevent your home from “exploding.” Buildings are typically damaged by wind and blowing debris – not by a sudden drop in air pressure. In fact, when a Tornado Watch is issued, you should close any open windows, doors and garage doors. Winds can enter building openings (especially though open garages) and cause walls to blow out and roofs to collapse.
• Take cover immediately when advised or when conditions are threatening.

Finding shelter

• In a house, go to the basement and take shelter under a stairway or a sturdy piece of furniture such as a table.
• In a house with no basement, go to a closet or a bathroom near the centre of the building, without windows. Lying in a bathtub with a mattress on top may provide additional protection.
• In a large building such as a grocery store or shopping mall, go to an interior hallway or a washroom on the lowest level, or get under a sturdy piece of furniture. Avoid large, open areas and stay away from windows.
• In high-rise buildings, go to the lowest level, a small interior room or a stairwell. Stay out of elevators and away from windows.
• If you are camping, hiking, biking or outdoors when a tornado is approaching, and there are no good shelters nearby, your situation is dire. Try to find a low-lying area such as a ditch and get into it. If there are no low areas, try to get deep into a thick cluster of trees and get down as low as possible. Protect your head from flying debris – small objects can become lethal projectiles when driven by tornadic winds.
• If you are driving and see a tornado in the distance, try to determine what direction it is heading and get out of its path if possible. If it is not possible to escape the tornado, find shelter. Do not take shelter under an overpass. If the tornado is approaching, get out of your vehicle and take cover in a low-lying area. If no good shelter is available, and debris is flying, your only option may be to park at the side of the road, leave your seatbelt on and get below the level of the windows. A strong tornado can easily toss or carry even large vehicles, but when absolutely no other shelter exists, your vehicle might provide some protection. Note that if a tornado seems to be standing still, it is likely either travelling away from you, or heading right toward you.

The Enhanced Fujita Scale

On April 1, 2013, Environment Canada's Weather Service introduced a new scale to measure the intensity of wind damage. This scale, called the Enhanced Fujita Scale or EF-Scale, is a more modern and improved version of the original Fujita Scale (F-Scale).

As with the original scale, the EF-Scale is a 6-point scale that goes from zero (weakest) to five (strongest). Its adoption unifies the approach to wind damage assessment in Canada and the United States, which adopted the enhanced scale in 2007 (all Canadian tornado examples provided below and prior to 2013 were assessed on the original F-Scale).

Many people think EF5 tornadoes only occur in the central U.S. “Tornado Alley”, but in 1953 a devastating F5 tornado struck within 110 km of Lambton County near the City of Flint, Michigan. Another F5 tornado hit Michigan in 1956 – this time in the Grand Rapids area. There has been only one documented F5 in Canada, which occurred in Elie Manitoba on June 22, 2007.

Facts

• Most tornadoes are less than a few hundred metres across, but the 2013 El Reno Oklahoma Tornado reached a width of 4.2 kms (about 2.6 miles) – the widest tornado ever recorded.
• Most tornadoes form near the south-west end of a storm, just when conditions seem to be improving. In fact, the sky may already be brightening in the distance.
• The air may be unusually calm just a few kilometres away from an active tornado. However, it is dangerous to be outside near a tornado because pieces of debris drawn into the storm can fall from the sky without warning.
• Some people have compared the sound of a tornado to a jet engine or a freight train, but some tornadoes produce no sound. Irregular crashing sounds could be from damage being caused by the tornado.
• Do not assume that you will see or hear a tornado coming. Tornadoes do not always have visible funnels and heavy rain often hides tornadoes.