A strong upper level trough and a dynamic atmospheric fuelled severe thunderstorms Tuesday afternoon in parts of southern Ontario, prompting tornado warnings for the Waterloo-Wellington, Huron-Perth and Grey-Bruce regions. While there hasn't been any twister confirmations at this point, there were reports of damage in multiple communities. The threat for storms will linger overnight as another round is expected to push in, reaching the GTA in the pre-dawn hours Wednesday morning. There could be more thunderstorms Wednesday as a result of a trough in behind the cold front. More on Wednesday's storm risk and beyond, below.
TUESDAY OVERNIGHT/WEDNESDAY: STORM POTENTIAL LINGERS IN BEHIND COLD FRONT
Tuesday was quite stormy in southern Ontario, as thunderstorms developed in Michigan and crossed the shorelines of Lake Huron in Ontario in the afternoon. The storms then prompted tornado warnings for the Huron-Perth, Grey-Bruce and Waterloo-Wellington regions. The storms then reached the GTA in the early evening hours, bringing powerful winds, heavy rain, hail and lightning, leaving many without power across the province.
The severe risk will linger as another round of thunderstorms is expected to move across the Lake Huron shores in the overnight period, reaching the GTA in the pre-dawn hours on Wednesday morning.
Then, a trough in behind the cold front that will pass through Wednesday morning will set up a non-severe storm risk in the afternoon. The threat will be scattered and isolated in nature, stretching from southwestern to northeastern sections. The main hazards will be heavy rainfall and strong wind gusts.
Temperatures won’t drop much in behind the cold front with winds remaining westerly-southwesterly. Daytime highs will remain in the mid-20s, accompanied by a bit of humidity, as well. Feels-like values will push close to the 30s or at 30 in many areas.
STORMHUNTER WINDS UP INSIDE POSSIBLE TORNADO NEAR LUCKNOW, ONT.
LOOK AHEAD: TEMPERATURES COOL, BUT POTENTIAL FOR PERIOD OF MID-SEPTEMBER HEAT
Beyond Wednesday, cool temperatures will move in late week -- a couple degrees cooler than seasonal -- with a risk for passing showers but mostly dry.
Temperatures will be warmer for the weekend, especially for southern Ontario. A period of showers and thunderstorms is expected to track across the region Saturday night into Sunday. Another system is expected to track to the north of the region early next week with the potential for another round of showers and thunderstorms.
The warm sector with this system will extend into southern Ontario. Southwestern sections will reach near the 30-degree mark, while the GTA will see mid-to-upper 20s on Tuesday. Cooler temperatures return mid-week, but potential for warmer weather late week and weekend.
Stay tuned for the latest forecast across Ontario.