The BC River Forecast Centre has issued a Flood Warning for the North Shore Mountains and Chilliwack River and tributaries as a series of atmospheric rivers continues to impact the province.
The North Shore Mountains received between 100 and 140 mm of rainfall during the first storm, which began Sunday. The Seymour River below Orchid Creek reached 207 cubic metres per second at 5:20 a.m. Monday, a flow rate that occurs between once every 50 to 100 years.
The River Forecast Centre has also upgraded Flood Watches for tributaries of the Lower Fraser, Vancouver Island including the Englishman River, and the South Coast including the Sunshine Coast, Howe Sound and Sea-to-Sky corridor.
The atmospheric river series, which began Sunday, is forecast to continue through the upcoming week. Rainfall totals from the first event ranged from 200 to 275 mm on western Vancouver Island, 30 to 90 mm on eastern Vancouver Island, and 50 to 80 mm in the Sea-to-Sky and Pemberton regions.
Freezing levels reached between 2,000 and 2,500 metres during the Sunday-Monday storm, with additional runoff from snowmelt expected from higher elevation watersheds. A Chilliwack River snow station at 1,620 metres elevation measured 40 mm of precipitation in 24 hours and lost 11 mm of snow water equivalent to melting.
Other rivers experiencing significant flows as of 8 a.m. Monday include Clowhom River near Clowhom Lake at 306 cubic metres per second and rising, Tofino Creek near the mouth at 303 cubic metres per second, and Elk River above Campbell Lake at 185 cubic metres per second.
The River Forecast Centre warned that active weather over the next seven to 10 days will create a prolonged period of heightened flood hazard across the B.C. coast, with increased risk in areas impacted by last week’s storms.
Authorities are warning the public about increased risks of unstable banks, river erosion, submerged roads, swift water hazards and landslides. Residents are advised to stay clear of swift running rivers, never drive across flooded roads or bridges, and keep storm drains clear of leaves that can impact urban drainage.
