The snowpack in the province’s mountain areas is getting deeper fast and raising the chances of spring flooding, say forecasters.
Provincial water forecasters taking measurements of the snowpack in the high country say the entire province has above-average levels.
“Persistent wet weather through January has led to rapid growth of the province’s snowpack,” says the latest report from the snow survey and water supply bulletin.
The province has automated stations scattered around the province, and does manual measurements monthly. The latest report highlights measurements taken earlier this month.
“The provincial average of snow measurements is 110 per cent of normal, up from 84 per cent of normal on Jan. 1,” the report says.
Increased seasonal flood risk conditions are developing in many regions, including the Upper Fraser — West, South Thompson, West Kootenay, Okanagan and Boundary.
“For snow-melt dominated rivers in the interior of the province, the likelihood of spring flooding increases with high snowpacks,” the report says. “This is most pronounced when snow basin index values approach or exceed 120 per cent.
“This does not mean that spring flooding will occur, rather the chances of flooding are increased.”
Right now, the Skagit area (southeast of Hope) has the highest snowpack at 134 per cent of normal, followed by the South Thompson at 130 per cent; the Boundary and West Kootenay are at 128 per cent and 126 per cent, respectively.
Moderately high snowpack (between 110-120 per cent) is also present in the Upper Fraser – East, Upper Fraser-West, North Thompson, Quesnel River (the western-draining areas of Cariboo Mountains), Upper Columbia, East Kootenay, Central Coast and Peace.
While typically two-thirds of the snow has fallen by this point in the season, an El Nino is throwing a bit of a wild card into the mix. The Pacific weather phenomenon could mean a cool, wetter spring.
“Given the current [El Nino] neutral conditions, it is reasonable to expect increased uncertainty over seasonal weather for the remainder of this winter and into spring. Near-term weather forecasts suggest on-going snow accumulation (at a seasonal to greater-than-seasonal rate) over the next seven-to-10 days,” the report says.
Long-range forecasts for an increased likelihood of cooler seasonal weather over the next one-to-three months also favour normal to above-normal snow accumulation over the remainder of the snow accumulation season.
The high snowpack doesn’t mean flooding is certain, the forecast centre emphasizes: a lot depends on the way spring weather plays out, how much rain falls, how fast the temperatures rise allowing the mountain snows to melt.
“Heavy rainfall during the snowmelt period has been a key driver in spring flooding in B.C., and can cause flooding irrespective of snowpack levels,” the bulletin notes.
Forecasters will head back into the mountains on the first of March to do further sampling of snow levels.