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.