Why you may not have received an alert until after 2 tornadoes struck Ottawa

Some residents of an Ottawa suburb are questioning the reliability of Environment Canada's weather alert system after they received alerts well after two tornadoes had already touched down in Barrhaven on Thursday afternoon.

"We got the alert 15 minutes after it struck," said Charlene Burnside.

She said she had been watching the skies after a tornado watch was issued that morning, but the storm hit her house and blew out windows before she received an alert on her phone.

Katie Gies said she didn't get the alert until she was sheltering in place eight minutes after she saw a tornado.

"I'm just thinking about our preparedness for extreme weather events and what our government and communication systems can do to make sure citizens are alerted timely and efficiently, because it really hasn't been done yet," she said.

"I think there's a lot of room for improvement. I feel like in 2023 we should have some sort of proper emergency alert so that everyone within a high risk area knows. Full stop."

Western University's Northern Tornadoes Project released an investigation report Saturday concluding that both tornadoes had a maximum estimated wind speed of 155 km/h.

One person suffered minor injuries and at least 125 houses were damaged.

Tornado warnings are complicated, meteorologist says

Tornado watches are the first line of defence, according to Environment Canada meteorologist Gerald Cheng. 

The agency issues a tornado watch when forecasters see that a system with the potential to cause a tornado is approaching.

"That's a good communication tool to warn the public that there is something coming, and there is a big risk," Cheng said.

For the agency to issue a warning, however, forecasters must either receive a report of a tornado on the ground or observe something on the radar, he said.

But the radar isn't a perfect tool.

A radar scan takes six minutes, Cheng said, so it may not always reflect the most recent weather conditions.

"By the time the data comes to our office, it could be six minutes old, so something could be on the ground already for six minutes at least," he said.

"Then you also have to factor in the time it takes somebody to draft and send that warning and the analysis before that."

Cheng said the alerts are important but that people need to be aware of their surroundings and get to safety when they see weather deteriorating.

"When we talk about tornado warnings, it's just one tool, but this tool is not 100 per cent," he said.

"It's like a fire alarm — when something happens or when a fire starts before you, we shouldn't wait for the fire alarm to take action."

'Not exactly an easy call'

Meteorologist David Sills, who runs Western's tornado project, said he was monitoring the radar in Ottawa Thursday morning after Environment and Climate Change Canada put out the tornado watch.

"It was not exactly an easy call on that one," he told CBC Radio's Ottawa Morning on Monday, describing how the Barrhaven tornadoes appeared on radar that day.

Environment Canada's tornado warning goals are to be successful 50 per cent of the time and to give people a lead time of 10 minutes 60 per cent of the time, Sills said.

The agency hired his team to analyze data and determine its effectiveness.

The first report card, based on data from 2019 to 2021, gave Environment Canada a score of 37.5/100, meaning it didn't pass, Sills said. Recommendations included that forecasters react faster when they see something on radar.

"A false alarm is not nearly as bad as a miss when it comes to these kinds of events," Sills said.

The agency improved in 2022, achieving a passing grade.

"We're hoping that that kind of progress continues and scores improve over time," Sills said.