Residents across southern Durham Region faced the potential for heavy rainfall and thunderstorms as an unsettled weather system moved through southern Ontario over the weekend.
The Durham Region thunderstorms prompted Environment Canada to issue a special weather statement covering Pickering, Ajax, Whitby, Oshawa, Clarington and surrounding areas. Forecasters warned that some locations could receive more than 50 millimetres of rain, with intense thunderstorms capable of producing rainfall rates of up to 40 millimetres in a single hour.
The rainfall was expected to be highly variable, meaning some communities could receive significantly more precipitation than others.
Multiple rounds of storms possible
Environment Canada said showers and thunderstorms developing over parts of Ontario were moving east toward the Greater Golden Horseshoe.
Because some storms could move slowly and pass over the same areas more than once, localized rainfall totals had the potential to climb quickly.
Residents were advised to watch for water pooling on roads and in low-lying areas. Heavy downpours can also increase the risk of temporary flooding near rivers, creeks and culverts.
Drivers were urged not to travel through flooded roadways because water depth and road conditions can be difficult to judge.
The Durham Region thunderstorms were part of a larger system affecting communities across southern Ontario, including the Greater Toronto Area and regions farther west.
Hail and tornado risk reported elsewhere in Ontario
Other weather organizations were also monitoring the possibility of more severe conditions in parts of southern Ontario.
Large hail was reported with storms near communities west of the Greater Toronto Area, while forecasts indicated that damaging winds and an isolated tornado could be possible in portions of the province.
However, Environment Canada’s Durham Region alert focused primarily on significant rainfall and thunderstorms rather than specifically identifying a tornado or large-hail threat for Durham.
That distinction is important for residents following local conditions, as severe weather hazards can vary considerably from one part of southern Ontario to another.
Cooler temperatures follow storm system
The unsettled conditions were also expected to bring a noticeable drop in temperatures.
After warmer and more humid conditions, Sunday’s temperatures across parts of Durham Region were forecast to remain around the high teens or low 20s, with additional chances of showers and thunderstorms.
Oshawa’s forecast called for a high near 19 C on Sunday, while Whitby was expected to reach approximately 22 C. Cooler conditions were expected to continue into the beginning of the following week before temperatures began recovering.
Residents urged to monitor weather alerts
Environment Canada encouraged residents to continue checking updated forecasts and alerts as the system moved through the region.
Weather conditions can change quickly during thunderstorms, especially when storms produce intense rainfall over a short period.
Anyone travelling during heavy rain should reduce speed, allow additional stopping distance and avoid flooded sections of road. Residents in areas prone to drainage problems should also watch for rapidly rising water.
The Durham Region thunderstorms serve as another reminder that localized summer storms can create significant rainfall even when neighbouring communities receive much smaller amounts.
Residents across Pickering, Ajax, Whitby, Oshawa and Clarington should continue monitoring official weather information whenever severe or rapidly changing conditions develop.
