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Analysts of the storm that formed an EF2 tornado and ripped a path through a Barrie neighbourhood on July 15 say they’re investigating the possibility that there may have been more than the five original tornadoes in Ontario confirmed that day which was later updated to six.
“The investigation is still going on, we’re busy with it just about every day just trying to get the entire scope of the tornado activity that day and make sure we get all of the details right,” said Northern Tornadoes Project (NTP) executive director David Sills. “To have six, maybe more, strong tornadoes from one event is pretty unusual, in Ontario anyway."
“We didn’t get, thankfully, the F4 or EF4 that happened in ’85 (the Barrie tornado in which 12 people were killed) but certainly it was a big event as far as the number of significant tornadoes and the number of places that were affected and the fact that one went right through an urban area.”
Barrie’s tornado was the most severe on July 15, hitting a southeast neighbourhood at about 2:30 p.m. with speeds of up to 210 km/h where it damaged dozens of structures. City officials initially issued 78 unsafe orders, 64 remain in place while necessary reports and repairs are done and two of the houses have demolition permits to remove everything above the first floor.
Examination of drone imagery has determined that when the tornado made landfall in Barrie, it travelled a total length of 12.46 kms and was up to 510 metres wide.
Damage caused by the other tornadoes was largely restricted to trees and some agricultural buildings, although a group of five campers had a harrowing experience when trees were upended on their site in Algonquin Park, knocking one camper unconscious and requiring two to have stitches.
Sills, whose team examined the Barrie damage hours after it happened, said the Barrie tornado tore a path closely following Mapleview Drive.
It started just west of Highway 400 where the first damage was found and then closely followed the road right into the southwest neighbourhood roughly where Mapleview intersects with Prince William Way. It continued on, close to Lake Simcoe, taking a bit of a turn and clipping Sandycove Acres where it did more damage before it finally dissipated even though the parent storm remained active across Lake Simcoe where the other tornadoes then formed.
“What happens is a lot of the rain-cooled air that’s associated with the thunderstorm can kind of sink under and cut off the tornado circulation and that’s probably what happened here and probably why it took a little of a right turn near the end,” said Sills.
Initially five tornadoes were identified, but the Sunbeam Lake campers at Algonquin Park alerted the NTP team that they had met up with a sixth, which was later confirmed through imagery.
Each one one of the tornadoes, said Sills, had different impacts.
The Lake Traverse tornado in the northern section of Algonquin Park as well as the Sunbeam Lake tornado tore paths largely through trees.
A tornado in nearby Dwight largely impacted a forested area with some populated areas but did not cause a great deal of damage.
The Lorneville and Zephyr tornadoes had more agricultural impacts with destroyed barns, a roof blown off a house and several trees toppled.
“When you get into what an EF2 does in a newer residential area, like the south end of Barrie, then you can see how much greater the impacts are, with nearly the same strength of tornado,” said Sills. “It makes such a difference on where they occur.”
EF2 and EF3 tornadoes are considered strong, while EF4 and EF5 are violent and EF1 and EF0 are weak.
Now the team at the Northern Tornadoes Project is looking at the possibility that the 30-km long Zephyr tornado may have actually been three tornadoes that occurred in succession.
“It looked like it was all connected. But when we started getting more higher resolution data, the drone data and the satellite data a new picture started to form where it looks like it may be three different tornadoes in there,” said Sills.
“There’s also new damage that was found up on the Ottawa River up near Pembroke, that looks like it might be a tornado as well…. There’s a lot of satellite review that still has to go on in between all these tornadoes to make sure that we’re not missing anything.”
“It just keeps on going up. Obviously it was a case where any thunderstorm that went up that day was probably going to produce a tornado somewhere.”
An aircraft will fly over Dwight, Sunbeam Lake and Lake Traverse and likely the Pembroke area to capture more high-resolution images to help in finalizing the ratings.
The goal of the NTP at Western University in London, from its onset four years ago, was to record every tornado in Canada. Sills said in the past, the Barrie tornado would have been recognized as would have a couple of others. Through remote sensing, other technical capabilities, along with the project’s ability to follow up with other damage, they’re able to get a better understanding of the bigger picture
“Sometimes they don’t seem like much, initially, and then you start looking at it and you realize that what you’ve been told about it is only a small part of something bigger,” said Sills. “This is what our project is about, it’s getting a fuller picture of tornado occurrence, whether it be across the country on a yearly basis or during an outbreak of tornadoes like we had on July 15.”
The body of knowledge up to this point allows the experts to estimate wind speeds based on the damage that’s caused, given the absence of on-the-ground, real-time wind measurements. When damage is restricted to only trees, a tornado hitting a forested area will rarely be rated larger than an EF2 because of the unknowns such as soil depth and interaction of trees, explained Sills.
Members of the NTP team are on a committee examining a new standard for the EF scale. It will include new rules and protocols for rating tree damage to allow analysts to get wind speeds from tornadic damage by analyzing the pattern of the downed trees. That new scale, he said, will then be applied to these affected areas that may show more severe wind speeds.
So far, the July 15 tornadoes are the country’s most significant weather event this year. The summer months, considered tornado season in Canada, has otherwise been on the quiet side with no tornadoes occurring west of Windsor. Records show that the Prairies have otherwise experienced tornadoes annually since 1959.
Nova Scotia, on the other hand, has had two this year after more than two decades or no tornadic activity.
