A Flood Watch for Squamish River and its tributaries, including Cheakamus River, has been upgraded to a Flood Warning. A Flood Warning means that river levels have exceeded bank full or will exceed bank full imminently, and flooding areas close to the affected rivers will occur.
Flows in the headwaters (Elaho River) on the Squamish River continue to rise. The current flow on the Squamish River near Brackendale is at 1540 m3/s, between a 2-year and 5-year flow. With additional rainfall, rivers are expected to rise more tomorrow and flows may reach or exceed 10-year flows. More rainfall on Wednesday would mean ongoing flood hazards, the River Forecast Centre warns.
Flows on tributary channels, including the Cheakamus River, are also expected to exceed the bank full from inflow and spill from the reservoir. Initial storms have delivered 80 to 300 mm through most of the region since Friday, with 40 to 100 mm falling in the past 24 hours.
A second atmospheric river is bringing another round of rainfall to the coast, with the heaviest amounts forecasted over West Vancouver Island and the Coast Mountains overnight into Tuesday. Temperatures are expected to warm during this period, and snowmelt at lower and mid-elevations will provide additional runoff to rivers.
Rivers have risen and are expected to experience periods of high flows overnight, with peak river levels expected to occur in most areas from Monday to Tuesday and possibly into Thursday. According to the River Forecast Centre, hydrologic modelling indicates potential flood conditions in areas with the heaviest rainfall.