A large low pressure system pushed into southern Ontario Monday afternoon and is expected to stall over the region until Friday.
Waves of moisture could bring upwards of 60 mm of rain to some places by the time all is said and done. A few communities have seen over 30 mm of rain so far with an additional 10 to 20 mm expected through Thursday.
Dense fog that reduced visibilities to near zero posed a safety risk on the 401 early Wednesday morning. The fog lifted by the afternoon hours, but scattered thunderstorms in some areas still gave drivers a lot to contend with.
Large hail hit the Exeter area, north of London and covered the ground along Highway 402 Wednesday morning. Another line of storm cells swept across the region throughout the afternoon and callers to The Weather Network Stormline reported damaging winds and downed trees in the city London. In Ayr, Ontario, it was raining so hard at one point that cars had to pull to the side of the road and wait for better visibility.
Environment Canada said the line of thunderstorms moved northeast at a rapid pace, producing winds with gusts over 100 km/h. There were reports of three brief possible tornadoes from two communities southwest of Kitchener as well as Fergus.
Moderate damage was reported at the Zellers and Canadian Tire in Fergus. “There have been some tree tops that ripped off and in the back of the Zellers building some of the siding has been torn off,” said Dave Patrick of ontarioweather.com.
Patrick adds that people at the Canadian Tire also noticed the winds getting stronger and stronger and then things just started to break and tear.
A tornado warning was issued for the city of Ottawa Wednesday evening, but was dropped only 15 minutes later.
The risk for isolated storms remains for eastern Ontario and southern Quebec. These areas have already been dealing with heavy rain. In Coaticook, Quebec about 100 people were forced from their homes Wednesday after the Coaticook River overflowed and flooded several homes.
Danya Vettese, a meteorologist at The Weather Network, says this system has brought all the right ingredients for strong thunderstorms.
“A warm front that slid through helped to drive temperatures up significantly and the warmer air is what helps to fuel the more severe storms.”
So far this spring, Ontario has been dealing with below normal temperatures and above average precipitation.
The city of Toronto, for example, has seen over 80 mm of rain this April, compared to the normal 62.4 mm for the entire month.
“And that's without the final totals from the recent system this week,” notes Vettese.
The La Niña weather pattern is contributing to the increase in precipitation and cooler temperatures. La Niña meaning the little girl, names the appearance of cooler than normal waters in the eastern and central Pacific Ocean. Simply put, it's called “a cold event.”
Most of the country has experienced a cool and wet spring thanks to La Niña. The trend is expected to dissipate in June.
With files from Matt Casey