Torrential rain over a short amount of time over the weekend and into Monday (Nov. 13-15) left many parts of the Cowichan Valley, including roads, highways, businesses and homes, flooded and emergency crews going non-stop.
An atmospheric river caused the weather event, which in parts of the region, dumped close to 180mm of rain on Cowichan according to Chris Carss, a Chemainus weather observer who records data on a volunteer basis for Environment Canada.
As for the atmospheric river that caused this weather event, “this seems to be a new term for the good old jet stream, that upper level wind circulation that determines the storm track at any given time,” Carss explained. “In this case, the jet stream was coming from the southwest, i.e. Hawaii, so we had a particularly wet version of the familiar Pineapple Express, no doubt intensified by – you guessed it – global warming.”
Rainfall totals overall for November could be record-setting with several days still left in the month.
Lake Cowichan Mayor Bob Day said the Lake area fared “quite well” considering the amount of rainfall.
“The usual low lying areas flooded, but most residents in those spots are prepared for the yearly high waters in the lake and river,” he said. “I have heard of some flooded basements around town, most likely caused by plugged perimeter drains that couldn’t handle the excess ground water.”
Robyn Roxanne recently moved to Lake Cowichan from Winnipeg and said she’s never seen anything like it.
“It was crazy to see,” she said. “My [house] was OK; my parents live up the road and their basement flooded.”
The town’s Chief Administrative Officer Joe Fernandez reported workers had to set up bypasses on some roads where water blocked some areas, making driving difficult.
Sahtlam firefighters and the RCMP were on Highway 18 the morning of Nov. 15 to deal with two incidents: a motor vehicle crash just west of Hillcrest and also a mudslide near Skutz Falls that jutted out a short distance into the westbound lane. The entire length of the highway, where there is a hill on the north side, water was visible weeping through the soil and onto the road.
Day said he, too, noticed the increased water flow across Highway 18 during the peak rainfall.
“This will probably be something that will need to be addressed in the near future because these extreme rainfall events are becoming the new normal,” the mayor said.
Warning preparedness meteorologist Armel Castellan, of Environment and Climate Change Canada, said he doesn’t care for the term “new normal” because he thinks “it’s a little bit dangerous” to think that this is what it’s going to be like henceforth.
“It’s a moving target,” Castellan explained. “We didn’t see a very strong wildfire season in 2019 after two record-breaking ones in ’17 and ’18 but just south of the border in 2020, it was fairly ridiculous. And then this past summer was also third place for hectares burned in the province. We are starting to see a huge uptick but we might also be talking about these last five years as a walk in the park compared to what we’re facing a couple decades from now when this is routine. It’s hard to say ‘new normal’ because it’s not a step function. It’s really a moving target and one that’s increasing in amplitude.”
Castallan said what the climate science says is that “we should expect events like this — atmospheric rivers and the heat wave of late June and other types of extremes — to be more frequent throughout the season and throughout the year, and to be longer lasting.”