Severe thunderstorm watch covers Toronto as heavy rain, damaging winds move in

Toronto residents are being warned to brace for heavy rainfall, damaging winds and large hail as a storm system moves across southern Ontario on Tuesday.

Environment Canada has issued a severe thunderstorm watch covering Toronto and most of the surrounding region, with the weather expected to persist into the evening.

Wind gusts up to 110 km/h possible

The federal weather agency is forecasting wind gusts of 90 to 110 km/h, Environment Canada said. The greatest likelihood of damaging winds is expected over southwestern Ontario.

The agency warned that hail ranging in size from a quarter to a ping pong ball is also possible, along with rainfall totals that could exceed 50 millimetres in areas hit by multiple thunderstorms.

Local utility outages are possible. Damage to roofs, fences, branches or soft shelters is possible.

Environment Canada is advising residents to monitor alerts and forecasts for updates as the system develops.

Conservation authority warns of rising river levels

The Toronto and Region Conservation Authority (TRCA) issued a notice Tuesday saying current conditions point to a higher potential for flooding from its river systems, because severe thunderstorms could drop heavy rain in a short period and cause water to overflow the rivers.

The agency urged residents to treat all shorelines, rivers and streams within its jurisdiction as dangerous, since the rainfall may cause rapidly changing water levels and stronger, faster flows.

Ground conditions are already working against the city. TRCA said its watersheds received five to 10 millimetres of rain Tuesday morning before the main storm arrived, leaving the ground partially saturated and limiting its ability to absorb additional rainfall.

That raises the risk that runoff will flow directly into rivers and streams rather than soaking into the ground, increasing the chance of localized flooding along waterways.

What residents should watch for

The storm threat stretches across much of southern Ontario, not just Toronto, according to Global News. The system is expected to continue into Tuesday evening before clearing.

Residents are being told to keep an eye on updated forecasts, secure loose outdoor items that strong winds could turn into projectiles, and stay away from rivers, streams and shoreline areas while the warning is in effect.