In addition to the rainfall warning in effect Saturday, Environment Canada has also issued a weather advisory saying conditions will be favourable for the development of funnel clouds.
"These types of funnel clouds are generated by weak rotation under rapidly growing clouds or weak thunderstorms," the advisory said. "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."
"Landspout tornadoes do not usually cause significant damage but can still be dangerous. They can be strong enough to topple trees, damage roofs or toss debris short distances."
Environment Canada says funnel clouds often develop without much warning.
"Treat any funnel cloud sighting seriously. Should a funnel cloud develop nearby, prepare to take shelter," it said.
The rainfall warning is as follows:
Rain, at times heavy, continues.
Hazard: Localized heavy rainfall with 50 to 75 mm possible.
Timing: Ending this evening.
Discussion: Heavy showers and isolated thunderstorms are expected to continue on and off throughout the day. These showers and thunderstorms are very slow moving and some areas may receive significant rainfall amounts.
For information concerning flooding, please consult your local Conservation Authority or Ontario Ministry of Natural Resources and Forestry office. Visit Ontario.ca/floods for the latest details.
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.
If visibility is reduced while driving, slow down, watch for tail lights ahead and be prepared to stop. Please continue to monitor alerts and forecasts issued by Environment Canada. To report severe weather, send an email to [email protected] or tweet reports using #ONStorm.