Localized heavy rainfall and funnel clouds are possible in the Toronto, Hamilton, and Niagara areas on Tuesday, Environment Canada says.
The weather agency has placed a large part of southern Ontario under a special weather statement, including the Golden Horseshoe.
“Slow-moving showers or thunderstorms are expected today across the region and some areas may receive significant rainfall amounts,” the statement said, noting that amounts of 30 to 50 mm are possible.
“Heavy downpours can cause flash floods and water pooling on roads … Localized flooding in low-lying areas is possible. Heavy rainfall in combination with other weather factors, such as hail, wind and lightning will make outdoor activities unsafe.”
A weather advisory is also in place for the Golden Horseshoe, warning that conditions will be favourable for the development of funnel clouds Tuesday.
It said that these type of funnel clouds are caused by weak rotation “under rapidly growing clouds or weak thunderstorms.”
“This weak rotation is normally not a danger near the ground. However, there is a chance that this rotation could intensify and become a weak landspout tornado,” Environment Canada said.
“Landspout tornadoes do not usually cause significant damage, but can still be dangerous.”
They could be strong enough to damage roofs, topple trees, or toss debris short distances, it said.