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Cool weather heats up risk for flooding as snowpack teeters well above normal

It has been 10 years since the province and the West Kootenay has witnessed snowpack levels at the current size — 128 per cent of normal — increasing the risk of flooding across the RDCK — Creative Commons.

Call it the calm before the storm.

A cool and wet spring resulting in an above-average snowpack perched in the alpine has the lowlands primed and poised for flooding when the heat hits.

It has been 10 years since the province and the West Kootenay has witnessed snowpack levels at the current size — 128 per cent of normal — increasing the risk of flooding across the Regional District of Central Kootenay (RDCK).

However, for the time being the flooding threat is only that: a threat. A reduced snowmelt rate means rivers, creeks and streams across the RDCK are flowing at seasonal to below seasonal levels.

“Weather plays a key role in whether flooding occurs, and cooler spring temperatures, periods of extreme heat, and wet weather can all exacerbate flood risk,” noted a press release from the RDCK on Wednesday. “The cooler temperatures through April and May have increased the risk of flooding if an extended period of extreme heat occurs in June.”

The key to emergency preparedness is knowing the risks and having a plan, assembling a family Emergency Kit and Grab and Go Bag. A plan should also include where to meet if evacuation is needed, including moving pets and livestock to a safe area, in the event the situation worsens and an Evacuation Order is enforced. Sandbags and sand are also available for residents at any of the locations listed on the RDCK website: www.rdck.ca/befloodprepared.

 Stay in the know

Sign up for emergency notifications, through Voyent Alert!

The RDCK uses the mass-notification system to send out critical information to residents and visitors in the event of an emergency.

People who might be at risk of flooding should also be aware that the province has expanded use of its broadcast intrusive system to include flooding and wildfire messaging.

“This allows local government and First Nations to use the service to alert residents if there is an imminent threat to life and public safety,” noted a release from the RDCK. “This system will be used to amplify Evacuation Orders in the RDCK.”

Source: RDCK

Be prepared

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.

 Not isolated

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