What is a derecho?

Torrential downpours and highspeed 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 them annually, particularly in flat areas prone to tornadoes.

“But for one which crosses populated centres in Canada?,” asked Cheng. “That’s rare.”

Cheng cautioned that there will almost certainly be more highimpact storms as summer approaches.

GRAHAM PAINE TORSTAR A woman with her grandson checks out an uprooted tree that severely damaged a neighbour’s home and crushed an SUV on Delaware Avenue in Burlington.