Highlights:

• Warm temperatures, melting snow, and significant rainfall forecast for overnight tomorrow through Wednesday, will lead to high water levels and potential flooding.
• Ponding, standing water, and localized flooding expected around the watershed due to the runoff.
• Smaller watercourses will rise and some could spill their banks into adjacent low-lying areas.
• Thames River is likely to rise enough to flood the low-lying area adjacent to the river, from Delaware down to Thamesville. In Chatham, the sidewalk along the river downtown is expected to flood over.
• Due to current ice conditions, the possibility exists for an ice jam.

Message:

A warm weather system has moved into the region, which is expected to bring daytime highs above freezing for the next week. The highest temperatures are expected tomorrow (Tuesday) and Wednesday. With these warm temperatures, forecasts are calling for 15 to 35 mm of rain overnight tomorrow thorough Wednesday. The warm temperatures and rain will also melt much of the snow leading to additional water running off the land.

Based on these forecasts, areas of ponding, standing water, and localized flooding are expected around the watershed. Smaller watercourses in the region are expected to rise, and some may spill their banks into adjacent low-lying areas. Many of these smaller watercourses and drainage ditches have been filled in with snow and ice which can block flows causing localized flooding. The LTVCA expects to have to operate the McGregor Creek Diversion Channel in Chatham.

The Thames River is also expected to rise. Based on current forecasts, it is highly likely that the river will rise enough to flood the low-lying river flats adjacent to the river, from Delaware down to Thamesville. In Chatham, at a minimum, water should be expected over the sidewalk along the river in the downtown. Water levels on the river should be expected to be elevated into early next week. An additional update will likely be required once the total amount of rainfall and snowmelt from the upper watershed is known.

The Thames River currently has a significant ice cover. Recent measurements at the mouth at Lighthouse Cove indicated around 30 cm of ice cover on the river. Measurements further upstream towards Chatham indicated around 20 cm of ice. Lake St. Clair is also still frozen over. Combined with the predicted flows on the Thames River, the conditions exist for a possible ice jam. Once the river ice breaks up and begins moving, conditions are highly unpredictable. Currently, as the rain has not even arrived, the timing of the river ice breaking up is uncertain. Residents should be aware that ice jams can cause water levels to rise rapidly and may quickly create flooding situations. In the past, high flows combined with an ice jam have backup up water all the way into the city of Chatham to an elevation that the 6th St. Dam would need to be operated. Conditions will need to be closely monitored in the coming days. Residents are advised to monitor local conditions and take appropriate precautions.

People should take extra caution and avoid the river, ditches, and streams. As water levels rise, the ice on these watercourses should be considered unsafe. The combination of slippery banks, unstable ice conditions, and fast-moving cold water can be dangerous. Standing water can also present its own unseen hazards. People should stay out of any flooded areas and not drive through flooded roadways. Children, pets, and livestock should be kept away from the water. It is not safe to take shelter along riverbanks or in low lying areas that are prone to flooding.

Officials will continue to monitor the situation and update this advisory as necessary.

This message will be in effect until February 19th.

Contact: Jason Wintermute ([email protected])