Flood Warnings and Advisories
High Streamflow Advisory – South Coast
ISSUED: November 25, 2017 04:00 PM
The River Forecast Centre is issuing High Streamflow Advisories for:
- Howe Sound including the Stawamus River, Cheakamus River and Squamish River and tributaries in the Squamish area
- North Shore Mountains including the Seymour River, Coquitlam River and surrounding tributaries
- Chilliwack including the Chilliwack River and upstream tributaries
A storm cycle over the South Coast last week has saturated the soil in this area. Heavy rainfall in the range of 50-100 mm is forecast over the South Coast Saturday night through Sunday. Freezing levels are expected to reach near 2500 m on Saturday night, providing additional snowmelt to the river systems.
River levels are receding or stable at this time. However, the flows are expected to rise again Saturday night through Sunday. Current modelling indicates that the streamflows are expected to reach to the same or higher levels as last Wednesday and up to approximately 2 to 5-year return period flows.
The River Forecast Centre will continue to monitor conditions and update this advisory as conditions warrant.
A High Streamflow Advisory means that river levels are rising or expected to rise rapidly, but that no major flooding is expected. Minor flooding in low-lying areas is possible.
A Flood Watch means that river levels are rising and will approach or may exceed bankfull. Flooding of areas adjacent to affected rivers may occur.
A Flood Warning means that river levels have exceeded bankfull or will exceed bankfull imminently, and that flooding of areas adjacent to the rivers affected will result.