As Ottawa prepares to get soaked by 20 to 40 millimetres of rain between Thursday afternoon and Friday, the Ottawa River Regulation Planning Board is now warning the rainfall could push flood levels around the national capital back up to the peaks reached last week.
Initially, the river board projected that water levels near Ottawa “should not exceed the initial peaks” during this week’s wet weather. But it revised that prediction in its latest forecast, published late Wednesday afternoon.
“Along the Ottawa River from Chats Lake down to Lac Deschenes, levels are expected to rise due to increased flow from the Abitibi-Timiskaming region combined with forecast precipitation,” the river board wrote.
“The levels along this river reach may return to the initial peaks observed last week.”
Downstream of Ottawa, from Pointe-Gatineau to the Grenville/Hawkesbury area, the river is expected to rise but not hit last week’s peak levels — however, that all depends on how much rain hits the region, the river board added.
Since the river crested last week, levels had been dropping around Ottawa, but slowly.
Environment Canada issues special weather statement
On Thursday morning, Environment Canada issued a special weather statement warning of “significant rainfall,” which said the rain will be heaviest on Thursday night and could cause “localized flooding in low-lying areas.”
“The ground, already near saturation, has a lessened ability to absorb further rainfall,” the statement said.
In anticipation of the rainfall over the next few days, the City of Ottawa has urged residents in communities impacted by the floods to “keep their sandbags walls up.”
The national capital has been battling the swollen Ottawa River for about three weeks now — the city’s second major flooding event in three years. Many townships and cities both upstream and downstream from Ottawa have been badly affected as well.
The city remains under a state of emergency, and the evacuation area in flooded Constance Bay in the city’s rural west end is still in place, city officials said on Wednesday. According to the municipality, 155 households evacuated voluntarily as waters rose ahead of last week’s peak period.
City staff said Canadian Armed Forces troops remain on standby in Petawawa and Ottawa if the municipality needs their help in the coming days.
Risk of thunderstorms on Friday
According to Environment Canada, the rain will taper to scattered showers on Friday and stop around noon — but there’s a possibility that thunderstorms could cap off the wet weather on Friday morning and afternoon.
While a “steady” temperature of 12 C is projected for Thursday, things might get a bit sticky by Friday afternoon. The agency forecasts a high of 20 C that day that will really feel like 25 C with the humidex.
The weather is expected to clear up over the weekend, with Environment Canada forecasting sun and a high of 17 C during the day on Saturday and a low of 5 C at night.
“Increasing cloudiness” and a high of 17 C are in the agency’s forecast for Sunday, with a low of 8 C and a 40 per cent chance of showers that night.