Environment Canada has issued a special weather statement for Metro Vancouver ahead of the arrival of an atmospheric river.
Prolonged heavy rain is expected to drench Metro Vancouver, the Fraser Valley, the Sunshine Coast, Whistler, and the Howe Sound starting Friday, Oct. 18 afternoon and continuing through Sunday morning.
Metro Vancouverites woke up to bluebird skies Thursday morning. Still, an atmospheric river is expected to bring rainfall amounts of 40 to 70 mm in general up to 100 mm in the coastal mountains starting around noon on Friday.
V.I.A.'s Downtown Centre Weatherhood station shows up to 20 mm of rainfall Friday followed by a jaw-dropping 98 mm Saturday. Sunday's forecast includes just over 20 mm of rainfall.
While atmospheric rivers can wreak devastation, such as the floods of November 2021, most of them aren't destructive. They also aren't rare, with the Lower Mainland seeing anywhere from 20 to 30 annually.
The 2021 weather event also included significant snowmelt of at least 100 mm on top of the 250 to 300 mm of rainfall. Current snowpacks aren't high enough to produce the same 2021 impacts, as this event is a month ahead of the former event.
Metro Vancouver weather forecast includes atmospheric river
Environment Canada meteorologist Armel Castellan told V.I.A. in a previous interview that conditions have been fairly dry for 30 to 45 days, and the hydrological system can absorb more precipitation than it could if Metro Vancouver had already received significant rain this fall.
While the signal isn't showing a powerful storm, the first atmospheric river of the year always carries a potential for damaging impacts.
"Any strong atmospheric river can cause problems because the environment hasn't been tested in this way," Castellan says.
Locals should brace for water pooling on roads, swollen rivers and creeks, and an increased risk of washouts, rockfall, and landslides. Ahead of the storm, they should clear drains of leaves and debris and secure loose objects.
Strong winds gusting up to 80 km/h may also cause power outages from tree damage on Saturday.
The rain and wind will ease by Sunday afternoon.
Stay up-to-date with hyperlocal forecasts across 50 neighbourhoods in the Lower Mainland with V.I.A.'s Weatherhood.
