A high streamflow advisory is in place for a number of waterways in the Lower Mainland including the Chilliwack River and surrounding tributaries.
“A series of intense Pacific storms are expected to impact the South Coast of British Columbia over the next few days,” according to the River Forecast Centre.
Strong winds and rising temperatures are expected to continue into Tuesday, with the heaviest rainfall amounts expected around the Sunshine Coast, Howe Sound, North Shore, and Fraser Valley (North).
While the Chilliwack/Vedder system has a high streamflow advisory, there is a flood watch issued for the Fraser Valley including tributaries from Coquitlam to Harrison.
Weather models indicate the potential for rainfall accumulations in excess of 100 to 150 millimetres over higher terrain, and lesser amounts at lower elevation.
River levels are expected to rise rapidly in response to the rainfall throughout Monday, and snow accumulations at mid-elevations over the past few days are expected to melt with warmer temperatures. This will contribute additional runoff to streams.
“Hydrologic modelling is indicating the potential for flood conditions to develop, particularly in areas with the highest forecasted rainfall amounts. Peak flows are expected late Monday and into Tuesday. As the storm passes on Monday, there will be increased certainty over rainfall amounts and the locations which have the greatest risk of high flows.”
By 3 p.m. on Monday, the Chilliwack River at Vedder Crossing was rising fast, but the water is up from already very low levels.
High streamflow advisories and high river levels are not uncommon in the Chilliwack/Vedder system in November.