ABCA - Flood Outlook - March 31, 2023

Ausable Bayfield Conservation Authority (ABCA) - Watershed Conditions Statement - Flood Outlook

24 hour rainfall totals of 40-50 millimetres (mm) possible

Minor flooding within low-lying flood plains is expected

An intensifying low-pressure system will track through southern Ontario today (March 31, 2023) and through tomorrow morning with the potential for up to 40-50 millimetres (mm) of rain.  

The heaviest rain is expected to come in two waves today, with the first wave reaching the Ausable Bayfield Conservation Authority (ABCA) area this morning.  As of 9:00 a.m. today, 5-10 mm of rainfall has been observed across the watershed. Forecasted rainfall through the morning and early afternoon has increased considerably from prior forecasts, and it is expected that heavy rains may result in an additional 25+ mm from this first wave before a period of light showers this afternoon. The exact track and timing of the second wave of rain is less certain, however, and additional 10-15 mm of rain is expected, beginning late this evening and overnight.

Based on current weather and streamflow forecasts, major flooding is not anticipated at this time. However, rivers will exceed bankfull, resulting in flooding of traditional low-lying flood plain areas. Streamflows in the smaller tributary creeks are expected to peak later today.  Should this forecast materialize, flows on the larger rivers are not likely to peak until later this weekend. Flows will remain higher than normal through most of next week. 

Residents are reminded to use extreme caution near all watercourses. Slippery and unstable streambanks, and extremely cold and fast-flowing water will combine to create hazardous conditions.

This message will remain in effect until 12:00 p.m. on Monday, April 3, 2023, unless rainfall totals and local conditions warrant further updates. The Ausable Bayfield Conservation Authority will continue to monitor forecasts and watershed conditions through the week and will provide updates as required.

Details also available at www.abca.ca.