High Streamflow Advisory issued for Howe Sound and Sea-to-Sky

The forecasted significant rainfall event has prompted a High Streamflow Advisory* by the River Forecast Centre.  

A significant atmospheric river is expected to impact southern coastal regions of British Columbia starting today. This is forecast to bring heavy rainfall throughout Saturday night and Sunday, and ease on Monday. Environment and Climate Change Canada have rainfall warnings in place with rainfall around Howe Sound to be upwards of 150mm total rainfall amounts expected by Monday.

Temperatures are expected to rise throughout the atmospheric river, with freezing levels pushing 2000 m elevation on Sunday before cooling on Monday. Additional snowmelt of recent snow accumulations at mid-elevations (1000-1500m) is expected to add to river runoff.

Rivers are expected to rise rapidly throughout Sunday in response to rainfall, and ease on Monday as the heaviest rainfall passes.  Current modelling is indicating the potential for flows in the 2-year to 5-year range.

*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. 

November 13, 2021