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High Streamflow Advisory for the Sea-to-Sky

Posted on November 23, 2021

As of 2:30pm, Tuesday, November 23, the River Forecast Centre is issuing a High Streamflow Advisory for the South Coast including:

  • Sea-to-Sky including areas around Squamish, Whistler and Pemberton

The public is advised stay clear of fast-flowing rivers and potentially unstable riverbanks during the high-streamflow period.

A prolonged period of active weather is expected throughout coastal BC over the coming week as several atmospheric rivers pass over the region. The first of these is expected to make landfall later on Wednesday, starting on the North Coast and Central Coast, and sliding southward into Thursday. This storm is expected to bring heavy rainfall, with rainfall totals in the 40-70mm range over the Fraser Valley and 50-80mm over the North Shore Mountains, and higher amounts possible over higher terrain.

Subsequent atmospheric river events are forecast on the weekend, starting up again later on Saturday. Additional storms are expected early next week. There is still considerable uncertainty over the locations and severity rainfall of the weekend and next week storm cycles, however the pattern of extremely active weather and heavy rainfall is expected throughout the advisory region.

Rivers are expected to see rises on Thursday in response to rainfall, with the potential for highest flows (2-year to 5-year) expected around the Sunshine Coast, Howe Sound and North Shore corridor. Rivers in the Fraser Valley are expected to see rises, though currently these are expected to be more typical in magnitude for fall storms, however these may be more problematic to flood response and recovery efforts and damaged infrastructure in the region.

Persistent periods of high flows are expected over the weekend and into next week. Additional information will be provided later in the week (Thursday and Friday) as weather and river forecasts see decreased uncertainty.

Details of the COFFEE and CLEVER Model forecasts can be found at:
http://bcrfc.env.gov.bc.ca/fallfloods/map_coffee.html, and 

The River Forecast Centre continues to monitor the conditions and will provide updates as conditions warrant.

To receive emergency notifications, sign up for Pemberton Alert.

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