A multi-cell system moving through Southern Ontario has brought intense rain in the past 24 hours, with gauges recording between 10 and 30 mm of rain across the region. Forecasts are calling for an additional 10 to 30 mm of rain and risk of thunderstorms Friday afternoon through into Saturday. Given the unpredictable nature of convective storms, localized precipitation amounts may vary and areas may experience higher than predicted rainfall amounts. High amounts of rainfall in a short period of time can lead to increased runoff and flash flooding, particularly in urban areas, and may temporarily overwhelm storm drain systems.

This amount of rainfall has the potential to elevate water levels into natural floodplain areas, parks and farm fields; roads may also become impacted. Soils may become saturated from the rain and could contribute to ponding, increased runoff into watercourses, and possible increased erosion and seepage issues.

Winds over Lake St. Clair are forecasted to be southerly, turning westerly with gusts between 40 and 60 km/h beginning early Saturday morning and continuing through the day. Residents along this shoreline may experience wind-driven high water levels and wave action, with a potential for erosion. Winds from southerly and westerly directions have the potential to cause a backwater effect in the Wallaceburg area, slowing the flow of water out of the Sydenham River and contributing to elevated water levels.

Winds over Lake Huron are forecasted to be southwesterly early Saturday morning, gusting near 50 km/h and continuing into mid-morning where winds are anticipated to become westerly, turning northwesterly Saturday evening. Wind gusts are anticipated to continue at this intensity into Sunday morning before subsiding Sunday afternoon. Residents along the Lake Huron shoreline, particularly those near Ipperwash Beach and in the Old Lakeshore Road area of Brights Grove, may experience increased wave action and possible erosion.

River banks and shorelines are expected to be slippery, with possible minor erosion. Residents are reminded to avoid watercourses and flooded areas due to slippery banks and 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.

This message will remain in effect until Sunday, August 30, 2020, unless otherwise updated.