Southern Ontario: Thunderstorm Outlook for Sunday, August 29, 2021

/
FORECAST UPDATED - Sun, Aug. 29 @ 4:50 PM

FORECAST UPDATED - Sun, Aug. 29 @ 4:50 PM

UPDATED DISCUSSION

We've reviewed the latest data and have made some small adjustments to our map. The main one is expanding the severe risk zone to include more of Southwestern Ontario including London and Woodstock. Some models are showing some strong storm development in this area over the next few hours. Any isolated storms that we see develop late this afternoon could bring large hail, damaging wind gusts and even some tornadoes.

Already seeing a line of storms starting to form over Northern Michigan and about to track across Lake Huron. This line will likely bring some damaging wind gusts to areas along the Lake Huron and Georgian Bay shoreline later today and into the evening. A few tornadoes can't be ruled out either with the strongest risk through Northeastern Ontario, but still strong enough in Southwestern, Central and Eastern Ontario to see a brief spin up.

Forecast Discussion (OLD)

A very active weather day is expected across Southern Ontario with widespread severe risk during the afternoon and evening on Sunday. The environment is favourable for any storms that develop to become quite intense will all severe hazards (large hail, damaging wind gusts and heavy rainfall). Current data suggests we’ll see some isolated pop-up storms during the afternoon along the Lake Huron shoreline and into Central Ontario around Lake Simcoe. These storms are where we have the risk for a few tornadoes along with very large hail.

We’re also expecting an organized line of severe storms to move across Lake Huron during the early evening stretching from Northeastern Ontario and down into Sarnia. This will track to the east bringing widespread wind gusts although there is some uncertainty about the coverage and severity of this second round of storms. The storm risk should come to an end around the midnight hour as the line of storms begins to weaken late in the evening.

We'd like to thank our sponsor for this forecast; Little Dreamers Collection!

Keep your little ones engaged with sensory fun from Little Dreamers Collection. Canadian-made scented playdough and sensory rice kits are what we do! Play is essential to child development and contributes to the physical, social and emotional well-being of children. Give your child the gift of play this summer!

Mention that you’ve seen this ad on Instant Weather for 15% off your purchase.

Visit their website littledreamersdough.ca for more details.

Northern Ontario: Thunderstorm Outlook for Sunday, August 29, 2021

/

Forecast Discussion

There is a very strong risk for severe storms throughout the afternoon and evening in Northeastern Ontario on Sunday. These storms could bring the threat of very large hail, destructive wind gusts and even the potential for a few tornadoes. The strongest risk stretches from Sault Ste. Marie through Elliot Lake/Sudbury and into Timmins/Englehart. We should see the storm risk come to an towards the late evening as the storms move out over Quebec.

Southern Ontario: Thunderstorm Outlook for Saturday, August 28, 2021

/

Forecast Discussion

Non-severe thunderstorms are possible across Southern Ontario during the day on Saturday. This will begin with some storm activity in Northeastern and Central Ontario during the morning with some isolated pop-up storms later in the day. It’s unlikely these storms will reach severe levels, but flooding could be an issue in areas that see multiple storms throughout the day.

Southern Ontario: Thunderstorm Outlook for Friday, August 27, 2021

/
SON_Low_Severity.jpg

Forecast Discussion

A few isolated storms may cross into Extreme Southwestern Ontario during the afternoon and evening on Friday. However, at this time it appears very questionable and if the storms develop they should be quite weak so a forecast isn’t being issued at this time. More organized thunderstorm activity is possible overnight into Saturday which will be covered in Saturday’s outlook.

Southern Ontario: Thunderstorm Outlook for Thursday, August 26, 2021

/
SON-TStorm-Day1.jpg

Forecast Discussion

Isolated pop-up storms are possible in parts of Southern Ontario during the afternoon and evening on Thursday. The areas most likely to see the storm activity includes London, Hamilton, Niagara and Kingston/Brockville. These storms should remain non-severe for the most part, however, severe thunderstorm warnings may be necessary from Environment Canada due to the potential for some heavy rainfall. Regardless, the storms will be quite weak so flooding will be the biggest threat along with strong wind gusts and small hail. The risk will come to an end late in the evening.

Northern Ontario: Thunderstorm Outlook for Wednesday, August 25, 2021

/
NON-TStorm-Day1.jpg

Forecast Discussion

Isolated storms may develop through parts of Northeastern Ontario along the Quebec border on Wednesday. This could bring the threat of damaging wind gusts, large hail, heavy downpours and maybe even an isolated tornado. The strongest threat is during the afternoon and into the evening. We should see the storm threat come to an end by late evening.

Southern Ontario: Thunderstorm Outlook for Wednesday, August 25, 2021

/

Forecast Discussion

The environment is favourable for some severe thunderstorm development throughout the day on Wednesday for parts of Southern Ontario. However, there is some uncertainty if storms will actually be able to develop. Some models aren’t showing much in terms of storm activity during the afternoon when the environment is the best for severe weather. While others are showing storms but earlier in the day during the morning when the environment will be weaker.

If we do see a few pop-up storms (latest data suggests areas around Lake Simcoe have the best chance), they could quickly become severe with strong wind gusts, large hail and heavy downpours. It should be noted that these storms will be extremely isolated so not every location in the risk zone will see a storm. The tornado risk is present and an isolated tornado can’t be ruled out, but we aren’t seeing any specific areas of concern so we haven’t included it in the map and it’s not super strong.

Storms will come to an end by the evening hours as the daylight heat that helped fuel these storms disappear after sunset.

Northern Ontario: Thunderstorm Outlook for Tuesday, August 24, 2021

/

Forecast Discussion

Some isolated thunderstorms are expected to develop over Southeastern Manitoba and Northern Minnesota, tracking into Northwestern Ontario by the late afternoon on Tuesday. These storms could have an isolated severe risk associated with them including large hail, damaging wind gusts and heavy rainfall. The tornado risk isn’t absolute zero, but it’s not strong enough to pinpoint on the map. An isolated tornado can’t be ruled out. The storm risk will continue overnight, but the severe risk will quickly dissipate after sunset.

Southern Ontario: Thunderstorm Outlook for Monday, August 23, 2021

/

Forecast Discussion

Another day of isolated pop-up storms are possible in parts of Southern Ontario during the day on Monday. This time the focus will be on Central and Eastern Ontario for these slow-moving storms that have the potential to produce small hail, strong wind gusts and very heavy downpours. Flooding could be an issue in some areas should a storm become nearly stationary over a particular location. The storm threat will come to an end later in the evening after the sun goes down.

Southern Ontario: Thunderstorm Outlook for Sunday, August 22, 2021

/

Forecast Discussion

Another humid and hot day will lead to some pop-up storms across Southern Ontario during the day on Sunday. These storms should be non-severe for the most part, however, like Saturday we could see a flooding threat and moderate size hail with some of stronger storms. Given that, we’ve decided to add an isolated severe risk through Central and Eastern Ontario, but important to note that most of the locations in this zone won’t even see a drop of rain. Any storms that have developed will start to weaken after sunset.