VANCOUVER — British Columbia’s latest snow survey shows the snowpack is 13 per cent above normal levels, creating an increased risk for spring flooding.
The May 1 Snow Survey Bulletin says a colder-than-normal April and start of May in the province has delayed the snowmelt.
The highest snowpack measurement is in the Upper Fraser West basin, which is 140 per cent above normal levels, while Vancouver Island’s snowpack is 108 per cent.
However, the bulletin says snow level is only one factor related to spring flooding, and the risk of flood is possible even with normal or below-normal snowpacks.
The River Forecast Centre says the risk will also depend on the temperature and rate of snowmelt and how much rain comes with that at the same time.
“Weather conditions from May through June determine the timing, magnitude, and rate of snow melt, where heavy rainfall events can exacerbate snowmelt-driven flows. An extreme heat wave – like the Heat Dome in late June 2021 – could lead to significant provincial flooding if it occurred between mid-May to mid-June,” the centre says.
It says the risk for major flooding would be a period of persistent cool temperatures and wet weather in late spring, followed by a sudden heat wave lasting at least five days.
The forecast centre says it will continue to monitor snowpack conditions and will provide an updated seasonal flood risk forecast in the May 15 bulletin, which is slated for release on May 20.
The bulletin adds that temperatures were lower than normal across the board for B.C. last month, ranging from -4.5 to -1.5 degrees colder than normal. It also notes that Nanaimo measured it’s highest total precipitation of all-time in April, with records dating back to 1892.
This report by The Canadian Press was first published May 10, 2022.
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