Flooding and landslide concern in southern B.C.
Wednesday, November 22, 2017, 10:00 AM - Heavy rain for the south coast of B.C. raises concern for possible flooding, avalanches, and landslides this week, induced by soaring freezing levels and an incoming atmospheric river.
A deep layer of tropical moisture will usher in mild air and heavy rain into the south coast, and typically snowy ski mountains will instead see rainfall, and on Tuesday morning, rainfall warnings covered Metro Vancouver, Howe Sound and the Fraser Valley.
"A plume of tropical moisture will continue to give rain heavy at times to Howe Sound, the northern sections of Metro Vancouver, the northern sections of Fraser Valley and near Hope today and tonight. Rainfall amounts near 45 mm have been reported since yesterday morning, further amounts of 50 to 70 mm can be expected by Thursday," Environment Canada says.
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This excessive rainfall will melt the already existing mountain snow at an accelerated rate, causing rivers to run high and increasing the risk of avalanches and landslides as the snowpack becomes unstable.
"Threat for flooding for the Comox Valley on Wednesday to Thursday, depending on the timing of tides and highest river levels, as well as rainfall amounts in the watershed and addition of snow melt," Weather Network meteorologist Tyler Hamilton.
At this point, freezing levels - or the point at which falling snow will turn to rain - will rise above mountain peaks and cause wet conditions.
Watch below: Soaring freezing levels
The unsettled pattern continues into the late week, but with lighter precipitation amounts and snow levels dropping to 1100-1500 metres. The next system comes in during the weekend with heavier precipitation, potentially raising snow levels back to 1700 metres.
There's low confidence this far out, but we will watch the potential for a stronger low, meaning a higher wind threat, early next week.