Another round of thunderstorms expected in Ontario & Quebec

I am back to reality after spending the last week on vacation in coastal North Carolina, a trip that was planned long before hurricane Florence. The Outer Banks fared well, there was standing water and sand on roadways, along with some beach erosion, but nothing compared to the historic flooding that continues in the rest of the state and into South Carolina.

Catastrophic damage in Dunrobin, Ontario after the EF-3 tornado last Friday, September 21. (CBC)

EF-3 Ottawa Valley Tornado
While I was away, summer ended and fall started with powerful thunderstorms in the Ottawa Valley. A strong cold front generated tornado producing thunderstorms late Friday afternoon. Environment Canada has confirmed three tornadoes with this extremely rare September outbreak. The strongest was a high end EF-3 tornado that produced wind speeds up to 265km/h. The tornado developed at 4:40pm near Dunrobin, Ontario, and moved east into Gatineau, Quebec. Damage was extensive, with nearly 50 homes destroyed in Dunrobin and over 200 buildings damaged or destroyed in neighboring Gatineau. Cars were flipped over and power poles were snapped like toothpicks, with thousands of trees toppled. An EF-2 tornado affected portions of Ottawa near Arlington Woods, with winds of 220km/h. A third EF-1 tornado, with winds of 175km/h hit the region near Calabogie and White Lake. The cleanup continues in earnest Tuesday, with officials worried about the new threat for rain and thunderstorms.

The outbreak produced at least 30 injuries, 5 of those critical. Power was out to over 250,000 residents in Ontario and Quebec after the storms late Friday. As of Tuesday morning, as many as 10,000 still remain without electricity. The City of Ottawa closed schools on Monday, and asked government employees to work from home, in an effort to relieve pressure on the cities infrastructure. On average, Canada records 60 to 80 tornadoes each year, but EF-3 and EF-4 storms are extremely rare in this country. Only one EF-5 tornado has occurred in Canada, at Elie, Manitoba on June 22, 2007, with winds of 420km/h.

Additional damage occurred from a second tornado near the Arlington Woods suburb of Ottawa (Edith Lalonde).

More strong thunderstorms
Low pressure over the Great Lakes, is forecast to move down the St. Lawrence Valley over the next 24 hours. Rainy, windy and cool weather is expected on Tuesday, as a warm front crosses the region. As much as 25-50 mm of rain may fall in Ottawa and Montreal. On Wednesday, a strong cold front associated with the low will sweep across the region in the afternoon, accompanied by showers and thunderstorms. Some of the storms may be strong, with heavy rain and gusty winds. At this time, it does not look like a repeat of the severe weather from last Friday, but we will need to see how unstable the air mass becomes Wednesday. Conditions will be warmer and more humid on Wednesday, with a high near 21C (70F) forecast for Montreal. Cooler weather returns Thursday into the upcoming weekend.

The calm after the storm on Hatteras Island, North Carolina. (ValleyWeather Photo)