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eye on spring forecast

Risk of spring flooding in Valley

Mar 9, 2020 | 3:01 PM

The high snowpack could lead to spring flooding in the Okanagan although seasonal weather is also a critical factor, according to the B.C. River Forecast Centre.

In it’s March 1 report, the centre states the overall provincial snowpack level increased slightly in February to 111 per cent, up one percentage from January.

“Moderately high snowpack, 110 to 120 per cent, is also present in the Upper Columbia, East Kootenay, Okanagan, Similkameen, and Peace (regions).”

However the centre points to volume inflow forecasts for the Okanagan (lakes) system that are 151 to 155 per cent above normal and are significantly higher than the overall Okanagan snow basin index.

“Seasonal flood risk is elevated in many regions, including the Upper Fraser West, Upper Fraser East, North Thompson, South Thompson, West Kootenay, Boundary, Central Coast and Skagit,” the centre release stated.

It says seasonal weather forecasts produced by Environment and Climate Change Canada are indicating an increased likelihood of cooler than normal temperatures for March through May for most of British Columbia, except in areas of the south coast and along the southern border.

However, the U.S. National Oceanic and Atmospheric Administration favours near-normal to above-normal temperatures across B.C. through the spring.

“Discrepancies between these two models may be an indication that the temperature and tele-connections currently present are creating increased uncertainty over the outlook for seasonal weather this spring. 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. This does not mean that spring flooding will occur, rather the chances of flooding are increased,” the release said.

There is one to two months left for snow accumulation so seasonal snowpacks and the seasonal flood risk can still shift.

“From a seasonal flood perspective, a scenario of a cool and wet spring would lead to increasing risk over the next four to eight weeks, whereas a warm and dry scenario may partially alleviate some of the current risk,” the release said.

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