Active weekend threatens Ontario with storms, rain, waterspouts
It’ll be an active, fall-like weekend across Ontario, but more summery conditions are on the horizon
Expect a raw and rainy weekend across southern Ontario as a potent upper-level low swings over the region. Heavy rain and thunderstorms could threaten outdoor plans throughout the region.
This is also the perfect setup for waterspout formation, so it'll be important to remain alert to the changing conditions.
Some regions could even see some wet snow with this active setup moving over Ontario.
Don't write off the summer season just yet, however, as pleasant late summer weather is expected to return and continue through the end of next week.
MUST SEE: Chasing ‘the most elusive weather’: Whimsical waterspouts
Friday:
A strong cold front will sweep into Ontario on Friday and trigger a risk for widespread rain showers and thunderstorms.
Above-seasonal temperatures sitting in the mid 20s will span the region ahead of the front’s arrival on Friday. But temperatures will soon plummet into the teens throughout the weekend.
September Outlook: Summer isn’t done with Canada just yet
We’ll see the cold front cut through the Nickel Belt and Lake Huron overnight Thursday and into the pre-dawn hours on Friday. This will push showers through northeastern Ontario with a risk for an embedded thunderstorm onto the shores of Lake Huron and into extreme southwestern Ontario.
The chance for showers will build across the Greater Toronto Area (GTA) through Friday morning. Through the afternoon, expect the chance for showers and thunderstorms to grow throughout the GTA, including Toronto, Hamilton, and the Niagara Peninsula.
Strong wind gusts and small hail will accompany the rain in areas that see storms.
Heavier pockets of rain will develop through the late afternoon and into Friday night across the eastern end of the GTA and into cottage country and eastern Ontario. The heaviest rain continues to shift east out of the GTA.
Saturday:
We’ll start Saturday with the heaviest rainfall pushing into western sections of Quebec, with clouds and scattered showers over southern Ontario and the GTA. There will be dry breaks in southern Ontario and the GTA, so Saturday won't be a complete wash out, but will still require some planning ahead.
Behind the front, daytime high temperatures on Saturday will come in 5-10 degrees colder than they were at the same time on Friday.
Cold northwesterly winds combined with instability of the upper-level low will send wrap-around and lake-effect rain showers across Georgian Bay, Lake Huron, and parts of the GTA. Wind gusts of 30-50 km/h are possible throughout the region.
DON'T MISS: Ontario on waterspout watch this weekend
These cold northwesterly winds blowing over the relatively warm waters of the lakes will generate some instability below, with a good chance for waterspout development.
During the late summer and early fall are prime times to see waterspouts, as cooler air begins to settle in, but the lake temperatures are still quite warm. This creates a temperature gradient and instability between the air and lake surface, causing the air to rise rapidly, even outside of the presence of thunderstorms.
Waterspouts tend to be slow-moving or near stationary, but sometimes move onshore, where they can cause minor damage or injury. It is best to keep an eye on the weather warnings in your area, and adjust any outdoor plans accordingly.
Sunday:
Clouds will build across the GTA once again on Sunday afternoon, with scattered showers expected through cottage country and a slight chance of some light rain in the GTA. High temperatures will remain in the teens.
FORECAST: Pleasant late summer weather is expected to continue through the end of next week
The periods of heavy rain and thunderstorms throughout the weekend will bring a risk of localized flooding in low-lying and flood-prone areas.
Header image of a waterspout over Lake Erie in 2020 submitted by Bryce Aitken.
