CALGARY, AB – Southern Alberta, including Calgary, is preparing for a substantial rainstorm this weekend, arriving on the 12th anniversary of the devastating 2013 floods. While meteorologists caution the event is significant, current projections suggest it will not necessarily replicate the extreme conditions seen over a decade ago, largely due to extensive flood mitigation projects and prevailing drought conditions.
Environment Canada has issued a special weather statement spanning a vast portion of the province, from Jasper to Medicine Hat, encompassing major cities like Calgary and Lethbridge. The brunt of the precipitation is anticipated in the Rocky Mountain foothills, where areas such as Pincher Creek and Waterton National Park could receive up to 200 mm of rain. Most other affected regions, including Calgary, are forecast to experience between 50 and 100 mm.
“We will see rainfall starting Friday afternoon and evening and then continuing through your Saturday, Saturday night, then starting to wrap up on Sunday,” said Christy Climenhaga, a scientist with Environment and Climate Change Canada. “So we’re expecting a lot of rain in a relatively short period of time.”
Despite the substantial rainfall, Climenhaga emphasized a crucial distinction from the 2013 event. “It’s a significant event. I don’t want to downplay how much rain that we’re going to get (but) at this point, it is not really looking to be the same as what we saw in 2013, where we saw some areas in southwestern Alberta pulling in 300-plus mm,” she stated. Cities like Edmonton and Red Deer are not included in the current special weather statement.
Adding to the complexity, mountain areas – including Highwood Pass east of Calgary, and Highway 93 in Banff and Jasper National Parks – could see rain transition to wet, heavy snow overnight, with up to 20 cm possible. Calgary’s overnight temperatures are expected to hover around 4 degrees Celsius on Saturday and Sunday. Strong northerly winds, gusting 60-80 km/h, are also forecast for Saturday, strong enough to potentially damage or topple trees.
Tricia Stadnyk, a professor in the Schulich School of Engineering at the University of Calgary, noted that while the storm initially appeared more menacing, it has significantly weakened in recent days. Furthermore, southern Alberta’s current drought conditions present a unique situation compared to 2013. “Unlike 2013, much of southern Alberta is suffering from drought, so river levels are unprecedentedly low and a lot of storage capacity in the rivers and lakes to absorb this type of rainfall,” Stadnyk explained.
While this increased storage is beneficial, the intensity of the downpour remains a factor. “We could still see rivers and lake level spike quite intensely as this rain falls, especially if it falls really suddenly within a one, two hour period – so that really depends on how the storm evolves,” Stadnyk cautioned. “When that happens, there’s still a risk of temporary flooding. For sure with a rainfall like this in urban areas, we expect to see some street level flooding, particularly on highways and things like that, at least in and around the heaviest peak of the storm. But all in all, there’s quite a bit of storage space out there.”
In anticipation of the storm, the City of Calgary has proactively begun lowering the water level in the Glenmore Reservoir, creating additional capacity for inflow from the Elbow River. Frank Frigo, manager of environmental management with the city, detailed their vigilance. “The City of Calgary has a hydrometric forecasting team that operates really 24-7 from the May 15 to July 15 period – and so about around Sunday we were starting to notice the evolution of a larger system that was likely to bring heavier precipitation to our area,” Frigo said. “So every six hours we run a series of models to be able to understand how river flows and levels might change and that’s allowed us to make some management decisions about water levels, particularly in the Glenmore Reservoir.”
The lessons from the 2013 flood, which led to the evacuation of over 100,000 people and an estimated $6 billion in damages, have spurred significant investment in mitigation. “In the 12 years since 2013, 71 per cent of the damage potential the city of Calgary had has been eliminated by measures that have been put in place,” Frigo asserted. He highlighted key projects on the Elbow River: “On the Elbow River, two of those important investments are the gates that were placed on the crest of Glenmore reservoir, which roughly doubled the storage handling volume for floods that we have at the Glenmore reservoir, and of course there’s the Springbank (offstream) reservoir that the government of Alberta recently completed construction of further upstream that adds about four times more storage.”
“We’re all holding our breath right now to see if this is the first trial or use of SR1.”
The Springbank reservoir (SR1) is particularly critical for this event, according to Stadnyk. “When this storm was forecasted, there was more rain falling in Calgary area than there was upstream, in which case something like the Springbank reservoir wouldn’t help much because we’re downstream of it,” she initially observed. However, the storm’s evolution changed its trajectory. “But over the last couple of days, it’s evolved so that that precipitation is falling in the foothills of the mountains and on the eastern slopes – in which case, SR1 (Springbank reservoir) is strategically positioned upstream of the city of Calgary and can be used in order to store some water temporarily and slow down the rise of the water levels and the peak that would hit Calgary as a result of a very heavy, fast and intense rainfall.” Stadnyk added, “We’re all holding our breath right now to see if this is the first trial or use of SR1.”
While catastrophic flooding is not anticipated, city officials expect some localized impacts. “Our normal stormwater drainage systems may be overwhelmed by the rainfall that we do get,” Frigo noted. He advised the public: “It’s important that people out driving or doing anything in the outdoors that they’re very careful about those conditions.” He further urged Calgarians “to make sure that they are prepared in terms of having their downspouts cleared and making sure that lot drainage around their homes don’t lead to any potential issues in terms localized flooding.”
For the agricultural sector and home gardeners, the incoming rain offers a welcome reprieve. Much-needed moisture is expected, especially in the Oldman and Milk River basins, which have been suffering from severe drought. Kath Smyth, a horticulturalist with the Calgary Horticultural Society, highlighted the long-term impact of dry conditions. “I don’t know if you remember January. It was long, it was cold and it was dry and as a result we’re seeing a lot of plant material that suffered during that,” Smyth recalled. “We need this moisture, we need to build ground moisture – it’s crucial to how we’re going to develop any kind of green.” However, with temperatures dropping near freezing in Calgary, Smyth advised gardeners to cover their plants as a precaution.
As the storm system moves in, residents are urged to stay informed through official channels and take necessary precautions, balancing awareness with the reassurance provided by extensive flood mitigation efforts.
