Tornadoes

Front Street, Sarnia (looking south) following the 1953 tornado.

 

A tornado is a column of rotating wind, travelling across the land at up to 100 km/h.  Wind speeds within a tornado can range from 64 km/h to over 500 km/h! 

Most tornadoes in Ontario occur from May to September in late afternoon and are most frequent during moderate summer temperatures, accompanied by high humidity. 

Here are some warning signs that may precede a tornado:

• Thunderstorms that grow in intensity, with heavy rain and severe thunder and lightning;
• Large hail (hail larger than a nickel is evidence of a very strong storm);
• An extremely dark sky, sometimes highlighted by rotating green or yellow clouds;
• Unusual darkness and an eerie calm at the end of a severe storm;
• A rumbling sound like a freight train, or a whistling sound like a jet.

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

  

Residents wander Christina Street following the tornado which struck downtown Sarnia in 1953.

Tornado Facts:

• Most tornados are less than a few hundred metres across, but during the Hallam Nebraska Tornado Outbreak of 2004, one of the tornadoes reached a width of 4000 metres - 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.
• It is not windy near most tornadoes and the air may be unusually calm just a few kilometres away.  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 hear a roar, but many tornadoes produce no sound.  If the sound is irregular, it is likely the result of damage occurring nearby; but if it is a steady, softer sound that originates in the sky or toward the main storm cloud, it is more likely caused by large hailstones hitting the ground or colliding in mid-air.
• Do not assume that you will see or hear a tornado coming. Tornados do not always have visible funnels (the condensation cloud that comes from a cloud base).  Evidence of a tornado may not be apparent until the "invisible" vortex reaches the ground and produces a debris cloud.  Dust and other material may be carried up into the air to combine with the condensation cloud, creating the characteristic funnel shape.  Heavy rain can also hide tornados.

Be Prepared:  Be Aware of Watches and Warnings...

Environment Canada will issue tornado Watches or Warnings when appropriate and local radio stations will usually broadcast such advisories as soon as possible. There are significant differences between Watches and Warnings:

A tornado WATCH is issued if conditions are favourable for tornadoes to develop later in the day - a tornado has not been sighted.  A Watch is usually issued early in the day, so monitor weather conditions and listen for updated weather reports.

A tornado WARNING is issued if one has been sighted, or if radar detects a tornado-like disturbance.  Residents in the area covered by a Warning will usually be advised to take shelter immediately!

When weather conditions look threatening, turn on your battery-powered radio and listen for weather reports.  If residents in your area are advised to take cover, do so immediately!


What to do when a tornado threatens…

• Take shelter immediately, preferably in the lowest level of a sturdy building.
• Stay away from windows, outer doors and exterior walls. Flying glass and debris blown into a building are extremely dangerous.
• Do not spend valuable time opening windows to prevent a building from "exploding."  Such action is unlikely to help because buildings are damaged by wind and by debris blown by the wind - not by a sudden drop in air pressure. 
• Take cover immediately when advised or when conditions dictate.

Finding shelter…

• In a house, go to the basement and take shelter under a stairway or a sturdy work table.
• In a house with no basement, go to a hallway, a closet or a bathroom near the centre of the house. 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 rooms 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.
• In a vehicle or mobile home, find other shelter immediately.  If better shelter is not available, lie in a ditch or culvert, but be aware of flash flooding.   Protect your head and watch out for flying debris - small objects can become lethal weapons when driven by tornadic winds.
• If you are driving and see a tornado in the distance, try to find shelter. If the tornado is close, get out of your vehicle and take cover in a low-lying area. If a tornado seems to be standing still, it is either travelling away from you, or heading right toward you!

The Fujita Scale...

The Fujita Scale is used to rate the severity of tornadoes as a measure of the damage they cause. The Scale was devised in 1971 by the Japanese-American meteorologist Tetsuya (Ted) Fujita, a pioneer in tornado research at the University of Chicago.  The Scale classifies tornadoes as follows:

F0 - light winds of 64 to 116 km/hr; some damage to chimneys, TV antennas, roof shingles, trees, signs, and windows.  F0 tornadoes account for about 28 percent of all tornadoes.

F1 - moderate winds of 117 to 180 km/hr; automobiles overturned, carports destroyed, and trees uprooted. F1 tornadoes account for about 39 percent of all tornadoes.

F2 - considerable winds of 181 to 252 km/hr; roofs blown off homes. Sheds and outbuildings demolished, and mobile homes overturned. F2 tornadoes account for about 24 percent of all tornadoes.

F3 - severe winds of 253 to 330 km/hr; exterior walls and roofs blown off homes, metal buildings collapsed or severely damaged, and forests and farmland flattened. F3 tornadoes account for about six percent of all tornadoes.

F4 - devastating winds of 331 to 417 km/hr; few walls, if any, left standing in well-built homes. Large steel and concrete objects carried or thrown great distances. F4 tornadoes account for about two percent of all tornadoes.

F5 - incredible winds of 418 to 509 km/hr; homes levelled or carried great distances. F5 tornadoes can cause tremendous damage to large structures such as schools and motels and can tear off exterior walls and roofs. Tornadoes of this magnitude account for less than one percent of all tornadoes. There has been one documented F5 in Canada, in Elie Manitoba on June 22, 2007.  F5 tornadoes are possible in Canada every summer.

Tornadoes in Lambton County

In Lambton, tornadoes have caused tremendous damage in the past.  In May 1953, a tornado struck downtown Sarnia killing seven people and injuring 40.  Damage to buildings and structures was extensive, being estimated at 59.7 million dollars (in year 2000 dollars).  Approximately 500 residents had to be evacuated.

The Sarnia Tornado… "On May 21, 1953, heavy rain and golfball-sized hail preceded the tornado that devastated the downtown.  The storm continued across Lambton and Middlesex counties, and passed just north of London.  In all, the storm was responsible for seven deaths, five of them in Ontario.  The tornado caused $5 million worth of damage in Sarnia. Sarnia's most damaged downtown landmarks included the Vendome Hotel, the Imperial Bank, Taylor's furniture store and the Imperial Theatre.  The theatre sustained so much damage that it was later demolished.  Debris cluttered Christina Street and trees were toppled along the half mile-wide swath of destruction the tornado left.  Pat McLean, whose family lived at the corner of Brock and Cromwell streets, said trees were falling all over the place.  "It was like somebody was playing pickup sticks and everything dropped," she said.  Geoff Lane of Sarnia was a new Observer reporter at the time and remembers watching a grey spiral cloud rotate above Port Huron.  He thought it was a dust devil phenomenon like he had seen in East Africa as he watched it cross the river behind a freighter and disappear from his view at about 5:40 p.m.  But when he left the office that was closer to George Street than the current building, he saw the devastation he had narrowly escaped.  Observer staff worked by flashlight at manual typewriters in the powerless city to get the news out.  As they worked, there were sporadic cases of looting after the storm.  Troops from Camp Ipperwash and members of the Royal Canadian Mounted Police were quickly called in to help local provincial police patrol the streets.  Police Chief Sydney Pratt declared the city under martial law, giving police the power to deal with looters, and acting mayor Clayton Saylor read the riot act from the steps of city hall in an effort to get people to disperse from the streets.  Residents and local industries aided in the cleanup, which began a mere hour after the storm ended." Copyright The Observer (Sarnia) 2003, All Rights Reserved.

The Reece's Corners Tornado... On May 2 1983, tornadoes brought destruction where they touched down in several locations across the County – from Walpole Island to the former Town of Forest.  Reece’s Corners in the former Township of Plympton was hardest hit, with fourteen homes and businesses seriously damaged, and thirteen people injured.  Eighteen families were temporarily left homeless.

Fortunately, tornadoes are a relatively rare occurence.  Every summer however, thunderstorms pass through our area which have the capacity to spawn tornadoes and damaging winds. 

Please also refer to the Severe Weather section of this website for additional information and visit The Weather Network or Environment Canada for current weather forecasts.