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Squamish region braces for potential flooding as storm approaches

As glacial melt combines with incoming heavy rains, experts warn that river levels could surge quickly, posing risks for recreationalists and drivers alike.

—Update: Aug. 14 at 6 p.m.—

The River Forecast Centre has issued a high streamflow advisory for the Sea to Sky Corridor.  

This means that area river levels are rising or expected to rise rapidly, but that no major flooding is expected.

"Fast-flowing bodies of water increase risk to life safety. Minor flooding in low-lying areas is possible," the advisory reads.

Due to the large amount of rain expected on Friday—50 mm to 80 mm in higher elevations— the region's rivers are expected to rise rapidly on Friday, and potentially into early Saturday.

"In glaciated river systems, such as the Squamish River, current streamflow is high due to recent warm weather and runoff from glacial melt, and these rivers may experience enhanced hazard for high flow during this period," the advisory reads.

"In other areas, particularly around Howe Sound and the North Shore Mountains, high streamflow in response to heavy rain is expected. While rainfall amounts are expected to be lower away from the coast, headwater areas around Whistler and Pemberton may still experience high streamflow from the rainfall. Current streamflow modelling is indicating the potential for flows around the two-year range. While these levels may not be high enough for specific flood concerns, high flows and rapid rises in rivers can pose a hazard for road washouts and public safety for recreationalists."

—Update: Aug. 14—

The latest forecast from Environment Canada says that on Friday and Friday night, Squamish could receive 50 millimetres of rain, with more than 80 mm expected over higher terrain.”

This is up from the 30 to 50 millimetres that was forecast a couple of days ago.

"An unseasonably moisture-laden frontal system will cross the B.C. south coast on Friday bringing heavy rain," the Environment Canada rainfall warning reads.

"The warm front arrives Friday morning with rain and strong southerly winds. The cold front arrives Friday afternoon and will bring the heaviest rainfall rates during the afternoon commute."

Residents and visitors should be on alert for the following:
- Poor visibility in heavy rain
- Water pooling on roadways with an increased risk of hydroplaning
- Sudden rises in water levels in creeks and rivers

"Recreationalists are advised to be aware of the potential for sudden rises in river and creek levels in response to the heavy rain over the mountains."

The downpour is expected to have eased into showers by Saturday.

As for the annual music festival—the Sp’akw’us Feather Shakedown at Sp’akw’us Feather Park—scheduled from 4 p.m. to 11 p.m. on Saturday, Squamish Arts says the show will continue as planned. 

"The event will continue rain or shine! We encourage people to bring appropriate clothing to keep warm and stay dry," a spokesperson for Squamish Arts said in an email.

The rainfall warning is also in effect for the North Shore—including West Vancouver and North Vancouver—as well as Metro Vancouver, including Coquitlam and Maple Ridge, along with Bowen Island and Gibsons.

This latest update to the rainfall warning was issued Thursday morning. 

More to come...

—Original story Aug. 12—

We might be in the midst of a heat wave, but rain is in the forecast and so is the potential for flooding. 

According to Squamish meteorologist Jason Ross, approximately 30 to 50 millimetres of rain is on the horizon, starting Friday before easing off at the end of the weekend. 

“Officially, there's nothing issued by Environment Canada or the River Forecast Centre. However, I can tell you, leading up to Friday into Saturday, right now, as of the latest and the greatest information, there is a very wet system that's on its way,” Ross said. 

“The system comes in on Friday, and we're looking at 30 to 50 millimetres of rain, kind of across the board for the Squamish area and certainly some of the mountains could see a lot more.

“It's a little unusual, but nonetheless, we need the rain, and we're in a pretty bad drought condition right now.”

Ross said that he anticipates there to be a break in the weather system on Sunday.

For anyone thinking of hiking or camping in the Squamish Valley this weekend, Ross suggests they should be prepared for the possibility of flooding. 

“I think one of the messages [to share] looking at all the ... data is that anybody hiking or camping, in the upper reaches of the upper Squamish Valley, especially, should be prepared for the possibility of some flooding, and Mud Creek possibly being washed out,” he said. 

“So be prepared to stay longer and have the appropriate supplies. I know there's been incidents out there in the past, and looking at some of the rainfall totals, by Sunday in the mountains, you know, we could easily see 75 millimetres in some of the local upper reaches. 

“That's not good. It's a lot of rain in a very short time.”

On Aug. 7, the Squamish River Forest Service Road was closed at the 21-kilometre mark until further notice, due to a washout at Mud Creek.

The Ministry of Forests told The Squamish Chief that the washout was created by a rain event on the night of Aug. 6. 

According to the ministry, safety assessments are taking place, and plans are being made by the designated road maintainer to complete repairs. 

There is no completion date known at this time.

"Advice for recreationalists is ... that the road is not currently accessible at the 21km mark, and to please stay clear of the washout and stay safe."

Cooler weather

While Squamish and the surrounding regions have been moving through a heat wave in the past few days, Ross said locals can expect a big drop in temperatures this weekend, particularly in the mountains.

“The temperatures are going to drop significantly in the mountains. It'll be a much cooler air mass behind the system and it'll bring the snow levels down to the tops of the mountains by Sunday,” he said.

“There's a possibility of some light snow, so some of the higher peaks could see the first dusting.”

Washouts and flooding

Dry conditions and hot temperatures have a big impact on whether or not flooding can occur. 

“One of the things that happens is, because it's been dry for so long, the water doesn't absorb, it runs off right away,” Ross said. 

“So any rainfall, it just runs right off, it doesn't get absorbed. Later on in the fall, it'll absorb into the soil and so on. But because we've been in drought conditions for so long and we just haven't had a lot of significant rain for months, it'll run off [causing washouts and flooding].”

As a local for the past 40 years, Ross said adventurers should keep an eye out on the creeks and river banks during a wet weather system. 

“I think anything along the banks, [people should] be careful of,” he said. 

His number one tip to those headed out camping or hiking this weekend is to check the weather forecast regularly.

Make sure to stick with the official forecast, which is the Environment Canada Weather Office,” he said.

RCMP warning

The Squamish RCMP also issued a warning ahead of the incoming rain this weekend.

“With heavy rainfall expected this weekend, we’re reminding everyone to use extra caution," a spokesperson for the RCMP told The Squamish Chief. 

"Slow down on the roads, watch for pooling water, and avoid unnecessary travel in hazardous conditions. Your safety is our priority,” 

*Please note this story was updated to include comments from the RCMP