Flood watch issued as thick, strong ice covers the Grand River

Temperatures well above the freezing mark, combined with between 35 and 50 millimetres of rain, freezing rain, ice pellets or snow, had the Grand River Conservation Authority (GRCA) issuing a flood watch for the entire watershed on Wednesday afternoon.

"There's a lot of uncertainty in this forecast still and depending on how that precipitation falls it will obviously dictate the level of risk," Cam Linwood, a spokesperson for the GRCA, told CBC News on Wednesday afternoon.

Snow melted as temperatures hit a high of 7 C at the Region of Waterloo airport on Wednesday. 

While significant flooding isn't expected and there isn't an immediate threat of ice jams, the cold January weather has made for a thick layer of ice on the Grand River, Linwood said, and when that happens, ice jams are possible. 

Thick, strong ice

"That ice had a chance to really firm up and get quite thick and strong. Having said that, it is generally a solid sheet," said Linwood. "As that ice melts, it can go one of two ways: that ice could slowly go away, but if it does break up into chunks and pieces of ice it does run the risk of getting jammed up."

Ice jams can form quickly and lead to flash floods. Flood co-ordinators will be keeping a close eye on areas prone to ice jams between now and Friday, said the conservation authority. 

GRCA reminded people living near the Grand River to familiarize themselves with municipal flood response measures, to stay off the ice and away from river banks — for their own safety.

According to the Environment Canada forecast, temperatures are expected to stay above the freezing mark until at about noon Thursday. Temperatures are expected to fall to a low of –14 C by Thursday night.