Snowpack levels are still above average in the Kootenays — but the rate of increase slowed down a bit in February.
“The conditions haven’t gotten worse since Feb. 1, but they haven’t necessarily gotten better,” says Jonathan Boyd, a hydrologist with the River Forecast Centre.
The latest report by technicians with the centre says snowpack in higher elevations in the West Kootenay is averaging about 121 per cent, while in the East Kootenay, it’s 110 per cent of normal.
That’s a little higher than the overall provincial level of 110 per cent, and below the highest average levels found in the Skagit, Okanagan and Thompson watersheds.
However, some areas of the Kootenays have received record amounts, like the Redfish station, which records levels in a creek that drains into Kootenay Lake. Other areas in the north Slocan and Arrow Lakes areas are recording levels more than 140 per cent of normal.
“For snow-melt dominated rivers in the interior of the province, the likelihood of spring flooding increases with high snowpacks; this is most pronounced when snow basin index values approach or exceed 120 per cent,” notes the March report. “This does not mean that spring flooding will occur, rather the chances of flooding are increased.”
The report is based on data collected from over 200 automated and manual snow monitoring stations scattered at high elevations across the province.
Not shrinking fast
The report says while the snowpack could potentially get deeper, it’s not likely to shrink much until the big spring melt.
“The snowpack won’t lessen, unless we have a significant warm spell in the rest of March,” says Boyd, though he notes the long-range forecast doesn’t predict much warming. “We’ll still see the snow increase for at least the next week, though it might get drier.
“But the big help in flooding would be having a really hot start to April, and melt away some of that lower-elevation snow, and then have it go cool for a week and then have another warm spell.”
Typically, 80 per cent of the annual snow accumulation has occurred by March 1, with another four to eight weeks of snow accumulation still to come, the report says.
It says while changes to the overall provincial seasonal flood risks are possible over the next few months (either increases or decreases), current trends in snowpack are likely to persist.
The report says after a wet January, precipitation was more modest across B.C. in February.
Coastal areas, including Vancouver Island and the South Coast, had below-normal precipitation. In the BC Interior February precipitation was near-normal to above-normal for most areas. In the West Kootenay, the month saw precipitation roughly half of normal.
High snowpack levels are one factor in determining if there will be flooding during the spring freshet, or snow melt.
The report notes discrepancies in long-range forecasting on spring weather. But the centre can’t say if that increases the likelihood of flooding.
“Seasonal weather forecasts produced by Environment and Climate Change Canada in late February are indicating an increased likelihood of cooler than normal temperatures for March through May for most of British Columbia […] Similar seasonal forecasts from the National Oceanic and Atmospheric Administration favour near-normal to above-normal temperatures across BC through the spring,” the report says.
“Discrepancies between these two models may be an indication that the temperature and teleconnections currently present are creating increased uncertainty over the outlook for seasonal weather this spring.”
Forecasters will head into the mountains again at the end of March to get a sense of how the snowpack continues to develop.