Record May windstorm in Ontario was a rare event says forecaster

Published: June 14, 2018

Updated: July 24, 2018

Author: Luke Jones



The May 4 windstorm that hit southern Ontario and particularly the Windsor region was a rare event, according to one weather forecasting company. Indeed, that storm has been described as a damaging event that does not happen often, making it tough to prepare for in catastrophe modelling predictions.

“While the combination of factors on May 4 was rare, it is important for insurers, and those modelling future catastrophes, to recognize that it’s often rare events like these that cause the most damage – and they are also the events that are difficult to generalize in model predictions,” Scott Kehler, president and chief scientist of Winnipeg-based Weatherlogics Inc. told Canadian Underwriter Wednesday.

Kehler points out that most modelling works on the assumption that severe summer windstorms are caused directly from storms, according to previous data. “However, in this case, the winds were actually from weak storms, which models would assume are rather benign,” he said. “In addition, a large amount of the wind damage didn’t come from storms at all, but rather a passing trough of low pressure, which again isn’t usually considered to be a mechanism which would cause damage like we saw on May 4, 2018.”

Across Ontario the windstorm resulted in $380 million in insurance losses, while in Quebec the effect was lessened but still cost insurance companies $30 million. As we previously reported, the storm was the costliest cat even in Ontario since Toronto’s 2013 floods, which resulted in $1 billion in losses.

The windstorm occurred on May 4 and caused considerable damage through Ontario and parts of Quebec. Roof damage was most commonly reported, while felled trees caused structural damage and blocked roads. Power outages were also frequent, CatIQ points out.

Winds reached hurricane force of up to 150 km/h in Ontario.

“It has been quite a damaging year so far,” said Kim Donaldson, vice president, Ontario, with Insurance Bureau of Canada (IBC). “This year alone insurers have already paid out three-quarters of a billion dollars, just five months into 2018.”

Weatherlogics believe the storm was among the worst in Ontario history, detailing the effect of the winds in a report published on Wednesday. In previous cases, low pressure or thunderstorms create the strong windstorms in Ontario.  “However, I’m not sure if these two factors have ever occurred in the same event and caused as much damage as we saw on May 4.”

“The fact that many wind speed records were set on May 4, including some that approached all-time records, suggest it’s unlikely any past events reached this magnitude.”