Updated thunderstorm forecast issued for southern Ontario

An updated thunderstorm forecast has been issued for southern Ontario for this weekend.

Environment Canada has issued thunderstorm outlooks for both Saturday and Sunday.

On Thursday, the weather agency said that thunderstorms were “likely” on Saturday for much of the region. But that has now changed, with forecasters saying storms are “possible” in some areas, while likely in others.

Here’s a look at what’s now expected:

Saturday a.m.

Overnight Friday into Saturday morning, scattered thunderstorms are possible in portions of southern Ontario (labelled location A below).

They could produce wind gusts up to 80 km/h and hail up to 2 cm in diameter, forecasters said.

Up to 35 mm of rain is expected locally with a peak hourly amount of up to 20 mm.

Other areas shaded in grey, which covers the rest of southern Ontario and portions of northeastern Ontario, could see isolated storms with up to 25 mm of rain.

Saturday p.m.

Environment Canada said that for the afternoon, thunderstorms are possible in most of southwestern Ontario (location A on the map below), which appears to include Hamilton, Niagara Region, and London, south to Windsor.

Forecasters said they will have the potential to product wind gusts of 90 km/h and hail up to 3 cm in diameter.

Up to 35 mm of rain is possible there.

In the afternoon and evening, portions of the Greater Golden Horseshoe, including Toronto, may see storms.

“Isolated thunderstorms are possible which have the potential to produce wind gusts up to 80 km/h,” forecasters said for those areas.

Up to 20 mm of rain is possible locally.

Parts of eastern Ontario, including Prince Edward County, Kingston, north to Ottawa, are likely to see thunderstorms in the afternoon and evening, bringing 30 to 50 mm of rain locally, Environment Canada said.

They will have the potential to cause wind gusts of 90 km/h and small hail.

“Multiple rounds of thunderstorms are possible which may give rainfall totals approaching 50 mm for a few areas,” forecasters said.

Areas west of Ottawa (location D on the map) are also likely to see scattered storms.

Local rainfall amounts of 30 to 50 mm are possible.

For the rest of the areas shaded in grey, which includes portions of southern and northeastern Ontario, isolated thunderstorms are possible in the afternoon and evening with up to 30 mm of rain locally.

Sunday

Early Sunday morning, isolated thunderstorms are possible in parts of eastern Ontario.

Isolated storms could also occur in parts of northwestern Ontario, including Kenora, overnight Sunday into early Monday.

Up to 25 mm of rain could fall locally.

Maps via Environment Canada