Tornado sirens, alerts ping Waterloo Region

Environment Canada issued severe thunderstorm and tornado-related alerts across parts of southwestern Ontario on Tuesday, May 19, as a line of storms moved through London and into areas including Waterloo Region. Phones in Waterloo Region received an emergency alert shortly after 6 p.m., and tornado sirens sounded on Western University’s campus in London. By Wednesday, the Northern Tornadoes Project at Western University said preliminary evidence confirmed a tornado touched down just southeast of London near Derwent. Cleanup and damage assessment were underway across the region on May 20. ### Why did Waterloo Region phones get a tornado alert if the confirmed tornado was near London? Waterloo Region residents were included in the mobile alert area as forecasters warned that conditions on May 19 were favorable for severe thunderstorms capable of producing a tornado. Environment Canada’s Waterloo forecast page said at 1:19 p.m. Tuesday that winds of 90 to 110 km/h, large hail and “a tornado is also possible” were part of the threat. The Region of Waterloo also posted a public safety notice earlier that day warning that severe thunderstorms can bring tornado risk. (kitchener.citynews.ca) Shortly after 6 p.m., the emergency message sent to phones said: “Tornado in this mobile coverage area.” CityNews reported that the alert reached as far as Waterloo Region while the storm was hitting London-area communities. Mobile alerts in Canada are issued by geographic coverage area, not by municipal boundary, which is why people outside the eventual damage path can receive them when forecasters see an immediate threat. (weather.gc.ca) ### What has actually been confirmed so far? The Northern Tornadoes Project said on May 20 that a tornado did occur just southeast of London in the rural community of Derwent. The group said video, radar data and a preliminary investigation carried out Tuesday evening provided the evidence needed to verify the tornado. A survey team was still expected to visit the area to determine the tornado’s intensity and track. (kitchener.citynews.ca) CBC reported Thursday that the project had confirmed the touchdown near Derwent after that preliminary review. CityNews, citing the same project, reported that storm-damage teams were being sent into London and across southwestern Ontario the next day. ### What damage was reported after the storm? London Hydro published photos of storm damage from May 19 showing fallen trees and damaged infrastructure in London, according to the CityNews report. (toronto.citynews.ca) CHCH said officials confirmed a tornado near London and reported trees and power lines down in the area after the storm. The Weather Network said Environment Canada’s event summary placed the tornado southeast of London at about 6 p.m. on May 19. (cbc.ca) Western University’s weather guidance says tornado warnings can be issued with little notice, sometimes an hour or less before impact. That matched the pace of Tuesday’s storm, when sirens on campus and phone alerts in surrounding areas were triggered as the line of thunderstorms was already moving through. ### What should residents in Waterloo Region and southwestern Ontario watch for next? Environment Canada’s current forecast pages for Kitchener-Waterloo and London showed calmer conditions by Thursday morning, May 21, after Tuesday’s storm system had moved out. (kitchener.citynews.ca) The immediate next step is not another warning bulletin tied to May 19, but the release of more precise damage findings from the Northern Tornadoes Project’s field survey. The Northern Tornadoes Project says its dashboard and open-data site are the public access points for event assessments and tornado information dating to 2017. (uwo.ca) Residents looking for official weather alerts can use Environment Canada’s alert pages, while local cleanup updates are being carried by municipal utilities and regional news outlets. (uwo.ca) (weather.gc.ca)