Highlights:

• Thames River will rise and flood the low lying river flats from Delaware down the Chatham.
• Ice cover on the Thames River will break up and may cause minor ice jams.
• Water levels on smaller local watercourses are now dropping but ice and snow blockages and related flooding are still possible.
• Rain in the forecast will keep water levels high throughout the week and may aggravate any ice jamming.

Message:

Over the last few days the Thames River watershed has experienced a warm spell. The warm temperatures have melted most of the snow in the Lower Thames watershed. In addition to the melted snow, late yesterday afternoon and evening the watershed received 5 to 15 mm of rainfall. Temperatures are now expected to remain below freezing until tomorrow afternoon, and then hover around the freezing point until another brief warm spell late Thursday, before dropping back below freezing Friday and through the weekend. Weather forecasts are calling for 5 mm of freezing rain overnight, a 10-15 mm of freezing rain tomorrow and another 10-15 mm of rain on Thursday. Before this warm up, many of the region’s smaller watercourses were filled with snow and ice. Ice cover on the Thames River was around 15 to 20 cm thick, possibly up to 30 cm around the mouth at Lighthouse Cove.

On the region’s smaller watercourses, water levels had risen and many had approached bank full conditions. In some areas, blockages of ice and snow had caused water to spill out of their banks. Water levels on these smaller watercourses now appear to be dropping. Blockages on McGregor Creek upstream of Chatham had caused water to spill out into the low lying flood flats, but water levels now appear to be dropping there too. Water levels are still high and should be expected to remain high over the next few days given the rainfall forecasts. The potential still exists for further ice blockages and localized flooding later this week.

Water levels on the Thames River in the City of London are expected to peak overnight. The amount of water leaving the Upper Thames watershed will cause flooding of the low lying river flats adjacent to the river from Delaware down to Chatham, beginning in the upper reaches tomorrow and making their way down to Chatham by Friday. Currently the ice on the Thames River appears largely intact. However, the warm weather and rain has weakened the ice particularly along the shorelines. In addition, flows on the Thames River are high enough that the ice will break up and begin to move downstream. There is the potential for minor ice jamming as the ice pushes its way downstream, which could lead to higher than expected water levels and additional water in the flood flats. The additional rainfall in the forecast would raise water levels even further and could lead to more ice jamming.

People should take extra caution and avoid the river, ditches, and streams. The combination of slippery banks, broken or unstable ice and fast moving cold water can be dangerous. Standing water can also present its own unseen hazards. Children and pets and livestock should be kept away from the water.

Officials will continue to monitor the situation and update this advisory if necessary.
This message will be in effect until February 9th, 2019.

Contact: Jason Wintermute (519-354-7310 x227, jason.wintermute@ltvca.ca) regarding this message.