La Niña has continued to wreak havoc on the West Kootenay.
A higher than normal snowpack and a delayed spring freshet could cause flooding in the region, especially along the shores of Kootenay Lake.
Cool temperatures have combined with the above average snowpack (128 per cent of normal) to lay the groundwork for the increased possibility of flooding during late May or early June if temperatures rise substantially.
Since May 19 the lake level at Queen’s Bay was 1743.52 feet, noted a joint press release from FortisBC and the Regional District of Central Kootenay (RDCK), and it was expected to rise two to three feet over the next week.
“Although lake levels are forecasted to remain below the 1752-feet flood level, the lake is subject to large natural inflows of water as a result of melting snowpack and precipitation,” said Nicole Brown, FortisBC corporate communications advisor. “This means conditions could change suddenly over the next few weeks.”
Since the beginning of March, FortisBC has discharged the maximum amount of water from Corra Linn Dam.
“However, at this time, Grohman Narrows, a natural geological formation located upstream of FortisBC facilities, is restricting water flowing out of Kootenay Lake,” Brown said.
The FortisBC release urged residents and businesses along Kootenay Lake to keep a close eye on lake levels for the next few weeks.
As well, people are asked to assess what impact rising lake levels may have on their property and be prepared in the event there is a sudden rise in lake level.
Brown said FortisBC provides daily updates on current and forecasted lake levels — people can visit fortisbc.com/lakelevel for current information.
People can also refer to rdck.ca/befloodprepared for flood preparedness information and sandbag locations. To sign up for emergency notifications on floods and other local emergencies in the RDCK, visit rdck.ca/emergencynotification.
To report a flood emergency contact the provincial coordination centre at 1-800-663-3456.
What is happening in the West Kootenay is also happening across the province.
Flood risk continues to increase through much of the province due to delayed snowmelt caused by persistent cooler spring temperatures, explained a release from the B.C. River Forecast Centre.
This delay has led to the highest provincial snow pack levels for May 15 since 2012.
“The greatest risk for potential major flooding is if a prolonged heat event occurs in late May or June,” the centre predicted.
The snow pack throughout British Columbia and the West Kootenay is well above normal. The average of all snow measurements across B.C. increased to 128 per cent over the past two weeks (May 1 was 113 per cent) primarily due to cooler temperatures across the province continuing to delay snowmelt.
Snow pack is only one factor related to freshet flood risk.
“Weather conditions from May through July will determine the timing, magnitude, and rate of snowmelt, where heavy rainfall events can exacerbate snowmelt-driven flows,” the centre release noted. “An extreme heat wave — like the heat dome in late June 2021 — could lead to significant provincial flooding if it occurred between late-May to mid-June.”
La Niña conditions
According to the Climate Prediction Centre there is a 58 per cent chance of La Niña conditions continuing into summer/fall (August-October 2022), with a 61 per cent chance that La Niña conditions continue into fall and early winter.
Historically, La Niña conditions can lead to cooler spring temperatures, resulting in delayed snowmelt and continued snow accumulation in the mountains.
“The colder than normal April and early-May conditions across British Columbia has increased the risk for flooding throughout the province by delaying the melt of snow,” the centre noted. “The major risks over the following six to eight weeks are an extreme heat event or widespread heavy rainfall events. A combination of several days of intense heat directly followed by heavy rain is a worst-case scenario.”
Source: B.C. River Forecast Centre
Timothy Schafer, Local Journalism Initiative Reporter, The Nelson Daily