Thunderstorm leaves 70,000 without power stretching from Sarnia, Mississauga, Brampton to Toronto

A severe thunderstorm with high winds has created power outages across Southern Ontario and led to at least one death.

Peel Regional Police say a woman in Brampton, Ont. died after a large tree struck her while she was out walking during the fast-moving storm.

Meanwhile Hydro One says more than 70,000 customers stretching from Sarnia, Ont. eastward past Toronto are without power after the storm toppled trees and powerlines.

Here are the latest outages in Mississauga according to Alectra:
Green 10-50 Customers
Pink 51-500 Customers
Orange 501-1000 Customers
Red >1001 Customers

The storm was severe enough for Environment Canada to issue a broadcast-intrusive emergency alert that goes out to television and radio stations and mobile phones.

Environment Canada meteorologist Daniel Liota says the winds of 132 kilometres per hour measured at the Kitchener, Ont. airport were enough of a risk to property and life to trigger the alert warning.

Liota says that while wind gusts of such speeds aren’t so rare in isolated microbursts, the storm was unusual in that it covered such a large geographic area.

“It was a big deal. It’s your upper echelon of thunderstorms.”

He says severe thunderstorms were only recently added to the alert system.

According to Alert Ready, which runs the warning system for Canadian governments, a severe thunderstorm warning has not gone out on the system in the four years of data listed.

To trigger a broadcast-intrusive alert for thunderstorms, there needs to be measured winds of at least 130 kilometres an hour, or hail of at least seven centimetres in diameter, which is about the size of a tennis ball, said Liota.

The Environment Canada weather station at Toronto Pearson International Airport measured gusts of 121 kilometres an hour when the storm blew through the city at noon.