After a cold, truly Canadian-style start to winter on Vancouver Island, another atmospheric river with rain and warmer temperatures is on the way.
The slow melt has already begun but with heavy rains expected to begin Tuesday, the BC River Forecast Centre is now watching the potential for flooding very closely.
“We’ve seen a lot of atmospheric rivers this season so it’s not atypical from that sense by any stretch however what’s more concerning or really has that kind of additive effect is the snow that’s on the ground,” said the forecast centre’s David Campbell.
The River Forecast Centre has issued a High Streamflow Advisory for Vancouver Island and B.C.’s South Coast that could be upgraded to watches or warnings Tuesday or Wednesday.
“Areas at low and mid-elevation would be of most concern. The Cowichan River, Koksilah River or basically anything on the east island could be affected. It might not get the most rain but will be affected by snowmelt,” he said.
“Current forecasts are to get freezing levels up to about 2,000 metres, so with the exception of the high mountains in Strathcona Park it’s looking pretty much like mountaintop freezing levels across the board.”
The exact track of the storm is still in question but some parts of the island could see 100 to 200 millimetres of rain combined with 100 mm or more of snow melt.
That will cause many rivers and creeks to rise rapidly into Wednesday.
In a statement released Monday afternoon, Emergency Management BC is urging people to get prepared in case of flooding.
To protect your home it suggests:
- Clearing out gutters, maintaining perimeter drains, making sure downspouts are far enough away from your residence and checking that nearby stormwater drains on your street are free of leaves and blockage.
With the risk of flooding and fast-flowing rivers in the days ahead search and rescue groups are urging people to stay away from river banks.
“Stay well back, as the flows increase it’s undercutting the banks and don’t want anyone going into that water because it’s going to be a challenge,” said Comox Valley Ground Search and Rescue manager Paul Berry.
Berry adds the incoming atmospheric river will cause alpine snow to become unstable which will increase the risk of an avalanche adding people heading into the backcountry should stay out of avalanche terrain.
An atmospheric river is a term used by meteorologists to describe a large, narrow stream of water vapours that can measure up to 1,600 kilometres long and more than 640 kilometres wide. As the band of precipitation crosses over land, it condenses into precipitation and can lead to well above-average rain or snowfall amounts.
Dean Stoltz
