Heavy rainfall forecast for Calgary through the weekend

Calgary is forecast to get a major drenching of rain in a short amount of time this weekend, but the city says no flooding over riverbanks is expected. 

Environment and Climate Change Canada said in a special weather statement that it expects the rain to start falling late Friday and continue until early Sunday, with the heaviest rain forecast to fall along the Alberta foothills. 

The agency said it expects 50 to 100 millimetres by Sunday afternoon with some areas, especially along the southern foothills, to see between 100-200 millimetres with the rain turning to snow in mountainous areas.

"It's going to be bringing quite a bit of moisture into southern Alberta starting Friday through the afternoon and then continuing at times very heavily through the weekend before wrapping up on Sunday. So we're expecting a very soggy weekend for the Calgary area toward the rest of the foothills and further south in the province as well," said Christy Climenhaga, a scientist with Environment and Climate Change Canada.

The province issued a high streamflow advisory for the Elbow River downstream of the Glenmore Reservoir on Thursday.

The city says it is preparing for a significant accumulation — but is not expecting any communities to flood.

Sandy Davis, who leads the City of Calgary's river engineering team, says there could be localized flooding in some of the low-lying park areas and pathway underpasses. 

"So we're seeing some of that low level response of a high river, but we're not anticipating flooding conditions," she said.

"But it does look like … it's going to be a significant rainfall."

Normal spring flow on rivers

In anticipation of the weekend rainfall, the Glenmore Reservoir is being lowered to make room to store river water, so that as the river rises the flow can be released downstream of the dam, Frank Frigo, the city's manager of environmental management, said in a release.

"Although significant river flooding is not expected in Calgary, we are preparing for higher than forecasted conditions," he said.

The city is reminding Calgarians to exercise caution around riverbanks, warn children about the danger of fast-moving water, stay away from any closed pathways and from any low-lying flooded areas near the river.

This weekend marks the anniversary of the record flood of 2013 that caused billions of dollars in damage. But compared to 12 years ago, this weekend's weather will spread moisture over a much larger area, the spring season has been drier, and the mountain snowpack is already mostly melted, Davis said.

"The city is far more prepared now than we were in 2013 to deal with floods of that size. So we've had significant investment and strides forward in the resilience that we have been able to put in place in the city," she said.

"From things like putting on the gates on the crest of the Glenmore Dam to building flood barriers throughout the city to the province's completion this year of the Springbank offstream reservoir."