Don’t be fooled by heat, lake is frigid

A weekend heatwave could make Okanagan Lake look inviting, but an ill-advised plunge into chilly water could prove fatal.

Air temperatures are forecast to crest 30 C for the first time this year but there won’t be a repeat of last year’s record-breaking heat at the end of June.

“This is not the heat dome 2.0,” Environment Canada meteorologist Armel Castellan said during a Friday media briefing. “But public safety around water bodies is critical. We do not want to see statistics like we sometimes do at this time of year with people accessing the very cold water and becoming hypothermic or getting swept away by high stream and river levels.

“Even though it’s hot, bodies of water are not,” Castellan added.

As of Friday, Okanagan Lake had a temperature of 17.5 C, about six degrees cooler than this time last year. Sudden head-first immersion in cold water can trigger an involuntary gasping reflex which can cause near-instant drowning.

With delayed snowmelt because of a chilly spring, many creeks and rivers are only now surging toward peak levels.

“We urge people to be cautious this weekend because flows in creeks and rivers across the vast majority of the province are extremely high, unusually high, for this time of year,” said Dave Campbell of the B.C. River Forecast Centre.

The flow in Mission Creek, the largest source of water into Okanagan Lake, peaked at more than 120 cubic metres per second on June 14, and hit 100 last Sunday, but has since fallen back to about 35 cubic metres per second.

RAIN RISK EASES, HEAT PUMPED UP

Sunshine may have replaced rainy conditions across much of British Columbia, but the warm spell may not offer respite from risks of flooding. Campbell said water levels are being watched closely as temperatures rise into the low-to-mid 30s.

“We do anticipate that this is certainly going to drive up snow melt rates across the province,” he told the news conference Friday.

British Columbia is in the advanced stages of the snowmelt freshet season, he said.

“We’re seeing now that the high elevation snowpack has advanced in terms of its melt,” Campbell said. “We’re about half to three quarters of the way through the upper elevation snowpack, and we are seeing that a lot or most of the mid-elevation sites are now snow free.”

Localized flooding has already been reported along some areas of Shuswap Lake, but officials predict levels will peak this weekend, avoiding severe overflow, while the City of Abbotsford says the Lower Fraser River will crest within six to nine days.

The city’s website says levels will stay high for several days once the peak is reached and “residents living in areas along the Matsqui Dyke and Glen Valley Areas may experience pooling of water or seepage.”

An evacuation alert issued two weeks ago by the District of Kent, just east of Abbotsford, is still in effect for properties at the mouth of the Harrison River where it joins the Fraser.

But drier conditions have allowed the District of Sicamous to lift the latest evacuation alert for 27 properties in a mobile home park at the base of a slope considered extremely likely to slide sometime in the next two years.

Castellan said high temperatures will cocoon most of the south coast, the southwest and central Interior regions all the way up to Dease Lake through the weekend into Monday.

“We're talking about five to 10 degrees above seasonal daytime high temperatures,” he said. “This is not record-breaking like we saw during the heat dome of 2021.”

Tuesday may see an end to the heat, with rain forecast for south of the Yellowhead Highway between Prince Rupert and Prince George, Castellan said.

“This is not a textbook event with dry cold fronts and lightning reaching dry ground the same way that we can sometimes see in the middle of summer, but it will bring precipitation again on Tuesday and it could be quite heavy.”

Campbell said the centre is also keeping an eye on the forecast for unsettled weather and thunderstorms, which could bring additional flood risks. Several areas are vulnerable to flooding from a combination of rain and runoff, but most of the province will “turn the corner” and go past the critical period of snowmelt over the next few days, he said.