Ausable Bayfield Conservation Authority

Statement Bulletin

Watershed Conditions Statement - Flood Outlook / Water Safety issued

issued  Thursday, January 11, 2018

Warm temperatures and rainfall combine for potentially high stream flows and possibility of ice jams

A Watershed Conditions Statement - Flood Outlook / Water Safety (Number 2018. S.1.1) was issued at Thursday, January 11, 2018 at 9:00 a.m. by Davin Heinbuck, Lands and Water Technologist:

Unseasonably warm temperatures are expected to continue through the day today (Thursday, January 11, 2018) and will remain steady around 8 degrees Celsius until early Friday morning. Forecasts are calling for an additional 10-20 millimetres (mm) of rainfall before temperatures drop back below freezing tomorrow morning.

Snowpack Water Equivalents range from 85-100 mm of water content. With the current warm-up and light rain that has already fallen, the snowpack has started to settle, reducing the capacity to absorb additional rainfall before running off. 

The warm temperatures combined with rainfall could result in high stream flows in area rivers and streams. The rate of snowmelt and runoff will depend on actual observed temperatures and rainfall totals that we receive over the next 24 hours. 

At this time, we expect that watercourses will begin to rise overnight Thursday and through the day Friday, with flows in the largest rivers not peaking until late Friday and into Saturday. Based on the current weather forecast and streamflow models, no major riverine flooding is expected. Flooding will be limited to traditional low-lying flood plain areas, including some local roads that may be affected by rising waters.

There is a risk of ice jams with this event, as river flows are expected to rise quickly and move river ice. The risk of ice jamming is limited primarily to the river mouth areas of Port Franks, Bayfield, and to a lesser extent Grand Bend. In addition to the movement of river ice, strong onshore winds forecast for Friday morning may push lake ice towards these river mouths, enhancing ice-jam potential and higher lake levels in the above mentioned areas. 

Municipal staff should monitor local drainage problem areas where snow conditions may have covered catch basins. Smaller rural watercourses have been drifted in by snow, which during a runoff, can block flows and back up water onto adjacent lands, resulting in localized flooding problems.

Residents are reminded that due to warmer temperatures and accompanying rainfall, all ice should be considered unsafe. In addition, please use caution near all watercourses. Slippery and unstable streambanks, streambanks hidden by drifted snow, and extremely cold water temperatures will create additional hazards.

This message will remain in effect until 10:00 a.m. Monday, January 15, 2018, unless local conditions warrant further updates. The Ausable Bayfield Conservation Authority (ABCA) will continue to monitor watershed conditions and will provide an update if required.

Types of Flood Messages

Watershed Conditions Statement (Flood Outlook/Water Safety): General watershed conditions suggest high runoff potential that could lead to flooding and remind the public of general river safety issues.

Flood Watch: Flooding is possible in specific watercourses or municipalities. Municipalities, emergency services, landowners in floodprone areas should prepare.

Flood Warning: Flooding is imminent or already occurring in specific watercourses or municipalities. Municipalities and individuals should take action to deal with flood conditions. This may include road closures and evacuations.

 

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