A plunging jet stream and a Colorado Low are creating favourable conditions for an active storm track over southern Ontario this week, bringing heavy rainfall and risk of thunderstorms.
A Special Weather Statement issued by Environment Canada states rainfall accumulations of 30 mm to 50 mm are possible between Wednesday and Thursday morning, with higher amounts possible in localized areas from thunderstorm activity. Some forecast models indicate that rainfall amounts could be as high as 50 mm to 75 mm for this 24-hour period.
Beginning late tomorrow morning, rainfall is forecast to continue throughout the day at rates between 2 and 7 mm/hr before subsiding Thursday morning. Higher intensity rainfall is possible in localized areas, particularly when associated with convective activity (i.e. thunderstorms). A brief reprieve is forecast for Thursday, followed by 5 mm of rain on Friday and a further 5 mm to 10 mm for Saturday. Over the next 5 days, the region could see between 40 mm and 100 mm of accumulated rainfall.
This amount of rainfall is anticipated to elevate water levels into natural floodplain areas, parks and farm fields. Soils are expected to be saturated from the rain and could contribute to ponding, increased runoff into watercourses, and possible increased erosion and seepage issues. High amounts of rainfall in a short period of time can lead to increased runoff and flash flooding, particularly in urban areas.
Individuals are reminded to avoid watercourses and flooded areas due to dangerous conditions, slippery banks, and cold, swift moving water. Children and pets should be kept away from the water.
The Conservation Authority continues to monitor watershed conditions and will issue advisories to municipalities and media should flood issues arise. Municipal emergency response staff and road superintendents should monitor local conditions closely. Please continue to monitor active weather alerts from Environment Canada.
This message will remain in effect until 12 p.m. on April 4th, 2025, unless otherwise updated.
