What is a derecho, and how can you protect yourself from future storms? A meteorologist weighs in

Torrential downpours and high-speed winds hurtled nearly 1,000 kilometres across Ontario and Quebec on Saturday, killing eight people and leaving much of the two provinces without power.

This type of storm is referred to by weather experts as a derecho,' which means straight ahead' in Spanish. A derecho is categorized by the shape of its path - a straight line, unlike the spiral shape which indicates, for instance, a hurricane or tornado.

Meteorologist Gerald Cheng said in an interview that a derecho is a widespread, long-lived windstorm" which accompanies a thunderstorm.

Thunderstorms and derechos can be related - and there could be embedded tornadoes in a thunderstorm," said Cheng. But it's important to note that straight line waves can be just as damaging and deadly."

These types of storms are not uncommon - much of the United States experiences these types of storms annually, particularly in flat areas prone to tornadoes.

But for one which crosses populated centres in Canada?," asked Cheng. That's rare."

The derecho was unsurprising to experts in the province: there were meteorological signs which pointed to a major weather event.

The ingredients for thunderstorms were there," said Cheng. The week prior to the storm was a hot one, and there was some heat and humidity in southern Ontario on Saturday."

Alerts were sent out to smartphones across the province using the Alert Ready infrastructure, which prior to last June did not include thunderstorm warnings in its roster of high-alert notifications.

The wind gusts were what prompted us to ensure that the severe thunderstorm warnings were appropriately broadcast," said Cheng. At the Kitchener-Waterloo airport winds reached 132 km/h." (The threshold for sending out a thunderstorm-related alert is recorded wind gusts at 130 km/h.)

Cheng cautioned that there will almost certainly be more high-impact storms as summer approaches.

We're in a transitional season, and sometimes we get these hotter and more humid air masses, which are the two necessary ingredients for thunderstorm development," said Cheng.

Derechos are made up of severe thunderstorms, and as we head into summer, there will be more severe thunderstorms. Any severe thunderstorms can cause damage, and in this case, they were deadly."

Cheng believes the best thing citizens can do to combat major weather events like Saturday's derecho is stay aware of their surroundings.

Mother Nature always gives us signals. When the dark clouds roll in, it's time to seek shelter. Don't wait."

With files from Isaac Phan Nay

Aisling Murphy is a reporter for the Star's radio room based in Toronto. Reach her via email: aislingmurphy@thestar.ca