Southern Ontario: Thunderstorm Outlook for Friday, June 18, 2021

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Forecast Discussion

A cluster of thunderstorms is expected to track across Southern Ontario during the morning hours on Friday with the highest chance for a thunderstorm around the Georgian Bay shoreline. These morning storms should remain non-severe although they could pose a localized flooding risk especially since many areas haven’t seen a lot of rainfall over the past few weeks.

The main story will be later in the day where there is an isolated severe risk during the afternoon and evening through parts of Southwestern Ontario around the Lake Erie shoreline. Storms are very likely to develop, but it’s unclear exactly where these storms develop. It’s possible we see them develop over Lake Erie and track stateside which would pose very little risk to the region. If they develop over Southwestern Ontario then we could see some damaging wind gusts, large hail and heavy rainfall from these storms around the Lake Erie shoreline and into the Windsor area.

Further north around Lake Simcoe and the GTA, there is a questionable severe risk if storms are able to develop early enough in the evening to take advantage of the environment which is looking unlikely at this point. As for the tornado risk, it appears the strongest tornado risk will remain south of the border although it can’t be fully ruled out if we get an isolated discreet storm that pops up in the prime environment.

Some storm development is possible overnight into Saturday however any storms that develop should be non-severe after sunset.

Northern Ontario: Thunderstorm Outlook for Wednesday, June 16, 2021

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Forecast Discussion

A few non-severe thunderstorms may track into Northwestern Ontario late in the evening from Manitoba on Wednesday. These storms will quickly weaken by midnight as they move eastward across the region. The main risks with these storms are heavy rain, small hail, strong wind gusts and frequent lightning strikes.

Southern Ontario: Thunderstorm Outlook for Monday, June 14, 2021

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Forecast Discussion

An area of rain with embedded non-severe thunderstorms is expected to affect areas around Georgian Bay, Lake Huron and into the GTA during the morning hours on Monday. The main concern with these storms is heavy rainfall with a few pockets picking up rainfall totals between 20-40mm by the afternoon. A more robust risk of thunderstorms will develop later in the day through the late afternoon and into the evening with all of Southern Ontario at the risk of seeing a thunderstorm. There are some indications that a few stronger storms could develop in Eastern Ontario that may reach severe levels with large hail, damaging wind gusts and heavy rainfall. The tornado risk with these storms isn’t particularly strong, but as usual, can’t be fully ruled out. The severe risk will come to an end by midnight although scattered showers and isolated non-severe thunderstorm continue through the overnight in Eastern Ontario

Northern Ontario: Thunderstorm Outlook for Sunday, June 13, 2021

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Forecast Discussion

Scattered non-severe thunderstorms are possible across much of Northern Ontario during the afternoon and evening on Sunday. These storms could produce small hail, strong wind gusts and heavy rainfall. One or two of these storms could potentially be severe particularly around the Quebec border, but it’s very questionable so we aren’t including a severe risk on our map at this point. Storms are also possible in the morning around the Manitoba border as some weakening storms track into the province.

Southern Ontario: Thunderstorm Outlook for Sunday, June 13, 2021

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Forecast Discussion

A weakening cluster of storms that brought severe weather to parts of Michigan on Saturday evening is expected to track into Southwestern Ontario during the early morning hours on Sunday. The main risk is between 12-4 am with a focus on the Windsor area and around the southern shoreline of Lake Huron. These storms will be quite weak by the time to reach our region with maybe some small hail, strong wind gusts and of course heavy rainfall with some lightning.

In addition to this, there is the risk of some pop-up storms over parts of Northeastern, Central and Eastern Ontario during the afternoon and evening. They should also be mainly non-severe although one or two cells could be quite strong and come close to severe levels. Still, the environment isn't really favourable for widespread severe activity. We’ll continue to monitor this and may need to introduce an isolated severe risk zone if it looks more probable.

Northern Ontario: Thunderstorm Outlook for Friday, June 11, 2021

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Forecast Discussion

Scattered showers with embedded thunderstorms are possible north of Georgian Bay including Manitoulin Island, Sault Ste. Marie and Elliot Lake during the morning on Friday. These storms will be quite weak with heavy rainfall and occasional lightning strikes being the main risks. Two rounds of storms could affect far Northwestern Ontario both in the morning and during the evening on Friday as storms track into the province from Manitoba. Small hail, strong wind gusts, heavy rainfall and frequent lightning strikes are all possible with these storms usually in the evening when they are expected to be stronger.

Southern Ontario: Thunderstorm Outlook for Friday, June 11, 2021

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Forecast Discussion

Scattered showers are expected to affect regions around Georgian Bay and Lake Huron during the early morning hours on Friday with the potential for a few embedded thunderstorms. Any storms that do develop should remain non-severe with heavy rainfall and lightening the main risks. Later in the day, there could be a few pop-up non-severe thunderstorms to the east of Lake Huron just to the northeast of London during the afternoon. Flash flooding could be an issue yet again as has been the case this week with slow-moving storms although it won’t be that widespread.

Northern Ontario: Thunderstorm Outlook for Thursday, June 10, 2021

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Forecast Discussion

A decaying cluster of thunderstorms that brought severe weather to parts of Manitoba and Northwestern Ontario late Wednesday is expected to continue to track eastward through the region overnight into Thursday morning. The environment is no longer favourable for these storms to remain severe so these nocturnal storms should be non-severe with small hail, strong wind gusts and heavy rainfall. They’ll reach Northeastern Ontario to the east of Lake Superior during the early morning as they slowly fizzle out by the afternoon hours. Widespread rainfall amounts between 25-50mm are possible within this line of storms so isolated flooding could be an issue. As mentioned, the storm threat will come to an end by late morning on Thursday.

Northern Ontario: Thunderstorm Outlook for Wednesday, June 9, 2021

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Forecast Discussion

Severe thunderstorms are expected to develop over central and western parts of Manitoba during the afternoon and evening hours of Wednesday. These storms will cross into Northwestern Ontario sometime late in the evening with the main threat being damaging wind gusts and large hail. There is also a marginal tornado risk with the storms, but it appears that the tornado risk will be highest over Manitoba in the early lifespan of the storms. The storms will continue to track eastward throughout the evening and into the overnight hours although they’ll begin to weaken and should be fully non-severe by midnight once they reach Thunder Bay and regions around Lake Superior. Non-severe thunderstorms are possible for Northeastern Ontario early in the morning on Thursday although this will be covered in Thursday’s thunderstorm outlook.

Southern Ontario: Thunderstorm Outlook for Wednesday, June 9, 2021

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Forecast Discussion

A cluster of slow-moving thunderstorms could develop through parts of Southwestern Ontario during the afternoon and early evening on Wednesday. These storms will be similar to what we’ve seen over the past few days so they should be the typical garden variety non-severe storms. However, due to the slow-moving nature of these storms, it could produce some localized flooding if a region gets stuck under one of these cells for a few hours. The main area of concern for this flooding potential is through the London, K/W and Brantford area along with Huron and Perth counties. This is where the latest data indicates most of the storms will develop although this zone may shift around depending on how the environment materializes. Storms will quickly fizzle out after sunset once the daylight heating that was fuelling them disappears.

Northern Ontario: Thunderstorm Outlook for Tuesday, June 8, 2021

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Forecast Discussion

Thunderstorms related to severe weather on late Monday across Minnesota are expected to reach the international border around Fort Frances overnight and into Tuesday morning. By the time the storms reach Ontario they’ll be quite weak so severe weather is unlikely. The main risks with these storms are some strong wind gusts, heavy rainfall and lots of lightning. They will quickly die out over Lake Superior during the late morning. Another round of storms should develop later in the day through the afternoon and evening hours east of Lake Superior in southern parts of Northeastern Ontario. One or two of these storms could bring some severe weather including damaging wind gusts, sizable hail and heavy rainfall. Flash flooding will be a major concern since these storms will be moving slowly and could easily dump 50-100mm over a location within a few hours. The storm threat will come to an end after sunset.