The River Forecast Centre is issuing a Flood Watch for:
North Shore and Metro Vancouver (including Coquitlam River, Alouette River, Kanaka Creek, MacKay Creek)
An atmospheric river is causing heavy precipitation along the BC coast today (Jan 31, 2020). The heaviest rainfall is currently being measured on the west coast of Vancouver Island and along the North Shore Mountains. Storm total rainfall amounts in the wettest areas may exceed 150-200 mm, with lower elevation and more protected areas expecting amounts in the 50-100 mm range. As the source of the atmospheric river is from the sub-tropics, temperatures are expected to warm in addition to the expected precipitation, with freezing levels pushing above 2000 m by late-Friday for the entire region.
Rivers are expected rise through Friday and into Saturday in response to this rainfall. The most impacted regions will be the North Shore and Metro Vancouver, which is being upgraded to a Flood Watch. It is expected that rivers will reach or exceed 5-year flows, including the Coquitlam River and Alouette River.
While some snowmelt is expected during this event, snowpack at higher elevations is deep enough that it will provide some absorption of the added rainfall and buffer the impact of the rainfall on runoff.
The public is advised to stay clear of the fast-flowing rivers and potentially unstable riverbanks during the high-river-level period.