British Columbia

Latest snowpack data shows heightened risk of flooding across B.C.

The latest snowpack numbers are in for British Columbia, indicating that several areas around the province are at a heightened risk of flooding heading into spring.

Weather going into spring will play a critical role in likelihood of flooding

Downtown Grand Forks under water during the floods of 2018. (Rafferty Baker/CBC)

The latest snowpack numbers are in for British Columbia, indicating that several areas around the province are at a heightened risk for flooding heading into spring. 

The biggest change since the previous bulletin, published last month on Feb. 1, is an increase in the snowpack around the Upper Fraser area, particularly around the headwaters east of Prince George. The snow basin is about 135 per cent of normal in the Upper Fraser. 

The snowpack is also higher than normal in the North Thompson and South Thompson, at more than 120 per cent of normal in both areas. 

"It's very rare that we've had high snowpack in the Upper Fraser and both the North and South Thompson at the same time," said Jonathan Boyd, with the B.C. River Forecast Centre.

"There's only actually been a few years in the last 50 or so that that's happened."

The last times snowpack conditions were similar across those combinations of areas goes back to 1999, 1974 and 1972. 

Boyd described the flood risk in many areas of the province as "quite substantial" particularly these areas:

  • Upper Fraser – West. 
  • Upper Fraser - East.
  • Cariboo Mountains (Quesnel River).
  • North Thompson.
  • South Thompson. 
  • West Kootenay.
  • Boundary.
  • Central Coast (Bella Coola).
  • Skagit basins.
A map showing the snowpack levels around the province as a percentage of normal. The darker the blue, the higher than normal the numbers. (River Forecast Centre/B.C. government )

Usually, by this time of year, about 80 per cent of the annual snow accumulation is over, with the rest coming over the next four to eight weeks. 

Above average snowpacks don't guarantee that flooding will occur — it's just one risk factor, said Boyd. The weather in the coming months will also play a critical role in the likelihood of floods. 

"The best case scenario to avoid flooding is actually to have a hot spell in March or early April," said Boyd. 

That would melt off some of the snowpack at lower elevations before the warmer weather in later spring melts off the rest of the snow. 

"The absolute worst case scenario would be to continue having snow accumulate anywhere into even the second week of May," he said. 

The next snowpack bulletin is expected to be published on April 8. 

With files from Brady Strachan

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