Significant damage in east London from Tuesday’s severe thunderstorms was caused by a downburst, not a tornado, according to researchers at Western University.
The Northern Tornadoes Project reported on Thursday that an EF1-rated downburst occurred during the storm, producing winds up to 145 km/h and creating a damage path across east London that stretched at least nine kilometres long and one kilometre wide.
This downburst knocked down numerous trees and damaged several buildings throughout east London, leaving thousands without power for hours.
Downbursts are strong winds that come down from a thunderstorm.
“(Trafalgar Street and Clarke Road) was near the heart of that damage. There was everything from part of an apartment building roof being torn off to many trees falling.. six power poles were snapped in half,” said NTP’s director, David Sills, in an interview on Thursday.
“It’s that kind of damage which puts you into the EF1 category on the Enhanced Fujita scale.”
EF1 is considered the second-lowest severity rating on the Enhanced Fujita scale, which includes wind speeds ranging from 135 to 175 km/h. A complete report from NTP is anticipated in the coming days.
WATCH | Tree knocked over outside London home during severe May 19 storm:
Intense winds amid tornado warnings knock down tree on front lawn of London home
A surveillance camera captured strong winds toppling a large tree onto the front lawn of London resident Becky Brown and knocking out power at Trafalgar Street and Bancroft Road on May 19, 2026.
Sills mentioned that it was somewhat challenging for the NTP survey team to evaluate the damage in east London and determine if it stemmed from a downburst or tornado.
“Part of it depends on how wide the.. damage path (is). If we’re seeing a really broad path, a kilometre or more, it’s typically due to a downburst. Tornadoes usually have narrower paths,” Sills explained, adding that tornadoes usually form in areas free of precipitation within storms.
“With the downbursts in east London, damage happened while heavy rain was still falling. The duration also lasted longer; it might be one or two minutes of extremely high winds compared to tornadoes where it’s generally over within about 10 or 20 seconds.”
The line of late afternoon storms prompted Environment Canada to issue red tornado warnings for places like London, Strathroy, St. Thomas, Woodstock, and areas further east toward Brantford.
Tornado researchers confirmed Wednesday that this same system created a tornado southeast of London in Derwent, Ont., just north of Belmont. The intensity and path of that tornado are still being verified, Sills noted.
“There was video showing dust swirling around in a large vortex along with many photos indicating rotation in clouds above,” he added.“In an initial investigation conducted on storm night itself , some shingles were damaged on houses , several large trees fell , and there was sign damage at Husky out there.”A fallen tree on Burnside Drive in east London, Ont., blocked access to a fourplex driveway. (Jack Sutton/CBC)
Houses along Burnside Drive had uprooted trees and fallen power lines due to Tuesday’s storm. (Jack Sutton/CBC)
Environment Canada meteorologists reported blown-out car windows, with one semi-truck overturned sideways around London’s area.
An official with Middlesex-London Paramedic Service statedno patients were taken to hospitals for injuries related to this severe weather event.
Accordingto London Hydro’s report , more than 6 ,000 customers lost power when peak conditions hit. Power has been fully restored as of Thursday morning.
Around2 ,700 customers outside Londons remained without electricity early Wednesday but they also regained service by Thursday.
The first recorded instancesof both Canada’s first tornadoes and downbursts occurred earlier this month just north of London according to the Northern Tornadoes Project. Both incidents received an EF0 rating under the Enhanced Fujita scale , which is classified as having the lowest severity level.
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