A tornado, severe thunderstorms and heavy rainfall hit southern Quebec

Environment and Climate Change Canada (ECCC) has confirmed a tornado hit the Mirabel area north of Montreal, as heavy storms hammered parts of southern Quebec.

As of 8 p.m., ECCC had lifted the tornado watches and thunderstorm warnings across the province.

The weather had people's phones buzzing throughout the afternoon.

Two severe weather alerts were issued in the Montreal area: one shortly before 3 p.m., warning of a potential tornado heading there and another sent at 5:08 p.m., about a possible marine tornado in the region.

"Tornadoes are often wrapped in rain and may not be visible," the second warning said, as rain battered the city. 

Simon Legault, an ECCC meteorologist, said high levels of humidity and warmth Thursday morning, combined with a sudden lift in air particles came together to trigger the tornado.

"We knew this morning that there were ingredients to create these thunderstorms and tornadoes as well," Legault said.

In a weather assessment published Thursday evening, ECCC said the province had been hit by "severe thunderstorms, heavy downpours and at least one tornado," referring to the the one it confirmed in Mirabel. 

The federal agency said the regions most affected were the Outaouais as well as the greater Montreal and Montérégie regions. It said a funnel cloud was reported in Vaudreuil but that it was working to confirm the event. A funnel cloud has similar properties to a tornado, but does not touch land.

ECCC estimates between 50 to 100 millimetres of rain fell in the Montreal area and said hail of one to two centimetres and gusts of wind of up to 98 km/h were registered in Dorval, downing trees there. 

The heavy rainfall lasted throughout rush hour and flooding closed several roadways in Montreal, including a portion of Highway 15 — a busy downtown expressway also known as the Décarie — at the height of Jean-Talon Street. 

In the hours leading up to the storm, half a million Hydro-Québec customers across the province lost power as forest fires in the James Bay region triggered grid protection mechanisms. Just as power was beginning to be restored, the numbers shot up again as the storm swept through. 

Trudeau airport said it halted some of its operations due to lightning in the area and encouraged travellers to check their flight status for potential delays. Flights have since resumed.

The initial tornado warning covered several areas, including Lachute, Vaudreuil-Dorion, Salaberry-de-Valleyfield and the region of Rawdon-Joliette. 

"The Doppler radar indicates a potential tornado over Laval tracking northeastward. This is a dangerous and potentially life-threatening situation," ECCC said on its website around 4:15 p.m. 

Tornado watches were issued for several areas of southern Quebec earlier in the day, including the Laurentians, Lanaudière, Lacolle and Mauricie regions and cities such as Drummondville, Saint-Hyacinthe, Victoriaville, Bécancour and Gatineau. 

The alerts came after a tornado touched down earlier today in the Ottawa neighbourhood of Barrhaven.

When ECCC confirmed a tornado had taken place in Mirabel at around 4:30 p.m., it did not share details about its size or damage. Photos and videos taken by residents emerged of cloud formations amid a backdrop of greenish blue skies.

In an emailed statement to Radio-Canada, city of Montreal spokesperson Gonzalo Nunez said the city was closely monitoring the development of the situation.

"Montreal is ready to intervene with its teams if damage occurs to municipal infrastructure and facilities, such as sewer backups, floods, water main breaks, fallen trees on public roads," he wrote.

Citizens can also call 311 to report flooding and other related issues. For an emergency situation involving the health and safety of people or the safety of a building, people can call 911 for help.

How to prepare and stay safe

According to ECCC, if you hear a roaring sound or see a funnel cloud, swirling debris near the ground, flying debris, or any threatening weather approaching, take shelter immediately.

Monica Vaswani, a warning preparedness meteorologist for ECCC, says a green sky could also be an indication of an imminent tornado.

"You want to head indoors immediately," she said. 

People should get to the lowest possible level of their home, preferably a basement, and keep away from windows and sharp objects. A fully enclosed space, such as a bathtub, can also provide some protection.

While a vehicle is not an ideal place to be during a tornado, if you do find yourself in that situation, keep low and hunker down in your vehicle, Vaswani says.