Where the derecho falls among Canadian Cat events

Canada’s rare and deadly derecho last week seems likely to rank among the country’s Top 10 costliest insured catastrophes, Aon plc predicts.

“In Canada, a rare derecho impacted densely populated metropolitan areas in Ontario and Quebec on May 21 that left at least 10 people dead and widespread significant damage to parts of Toronto, Ottawa, Montreal, and Quebec City,” Aon’s Impact Forecasting states in its Weekly Cat Report for May 27, 2022.

“Preliminary estimates indicated…the derecho could be one of the Top 5 or 10 costliest severe convective storm events on record for the Canadian insurance industry.”

Glenn McGillivray, managing director of the Institute for Catastrophic Loss Reduction (ICLR), compared the derecho’s damage to that caused by a severe weather event that hit Ontario and Quebec in 2018.

“I’m comparing it to the May 4, 2018, storm in southern Ontario and Quebec,” he told Canadian Underwriter the day after the storm. “That storm was a big flatline windstorm, no tornadoes or anything like that. It caused over 54,000 personal lines claims and the damage exceeded $600 million insured.”

Last week’s derecho — a type of widespread, long-lived windstorm associated with a band of rapidly moving showers or thunderstorms — registered wind gusts of between 100 km/h to 140 km/h per hour across Ontario and Quebec, resulting in exceptional straight-line wind damage, Aon reports. The storm spawned at least two reported tornadoes.

At least 1 million hydro customers across southern Canada lost power as the storms passed.

“In Ontario, Hydro One reported large electrical transmission towers near Ottawa were toppled during the derecho, while no fewer than 1,000 power poles were knocked down province wide,” Aon reports. “This led to at least 500,000 customers in Ontario losing electricity. Tens of thousands of customers remained without power for multiple days.” Media reports suggest many are still without power.

Nine people died as a result of falling trees and limbs during or after the storm. Another person died when their boat capsized during the storm.

“Regionwide, destructive winds, heavy rainfall, and hail resulted in numerous damaged or destroyed homes and structures, blown off roofs, flipped vehicles, impacted agricultural operations, and impassable roadways,” Aon writes.

In Quebec, 550,000 people lost power, and widespread downed trees resulted in extensive damage to homes and vehicles – particularly along a swath between Upper Gatineau and Montmagny. A maximum wind gust if 89 mph (144 kph) was reported near Lake Memphremagog.

“A local state of emergency was declared in the communities of Clarence-Rockland [located in eastern Ontario], and Uxbridge [in south-central Ontario] due to locally enhanced losses,” Aon reported. “In Uxbridge, storm surveys determined damage was heightened by an EF2 tornado with maximum wind speeds reaching 120 mph (195 kph). As of this writing, a second tornado was confirmed in Casselman, a village in Eastern Ontario.”

With files from Alyssa DiSabatino

Feature photo courtesy of iStock.com/Christina Farrell