The April 1 snow survey is now complete. Data from 143 snow courses and 68 automated snow weather stations around the province, collected by the Ministry of Environment Snow Survey Program and partners, and climate data from Environment and Climate Change Canada have been used to form the basis of the following report.
Cool and wet weather through March has led to a significant increase in snowpack conditions across the province, with the biggest increases being observed in south and south-east BC. Provincially, snow basin indices trended closer to normal, with the provincial average for all April 1st snow measurements at 98 per cent of normal. This has increased from the average of 85 per cent for March 1.
Snow basin indices for April 1, 2017 range from a low of 62 per cent of normal in the Liard to a high of 123 per cent of normal in the Lower Fraser. The North Thompson is at 103 per cent, the South Thompson 106 per cent, and Okanagan 105 per cent.
With extremely wet weather through March, many rivers of the province are flowing well above normal for early April. Snowmelt at lower elevations has led to increased runoff in smaller stream systems and the start of freshet flows in some large river systems.
Seasonal volume runoff forecasts are near normal for most basins across the province. Higher than normal seasonal runoff is expected in the Nicola and Okanagan basins.
By early April, 96 per cent of the annual B.C. snowpack has typically accumulated, with maximum accumulation generally occurring in the middle of the month.
Significant snow accumulation over the past month has led to an increase in seasonal flood risk across most of the province.
Most areas of the province are entering into the spring freshet with normal levels of seasonal flood risk. This includes the Nechako, Middle Fraser, South Thompson, North Thompson, Upper Columbia, Okanagan and Similkameen. The West Kootenay and East Kootenay have moderately high snow packs, and subsequent moderately increased seasonal flood risk.
With two to four weeks remaining in the snow accumulation season, the River Forecast Centre says changes to the seasonal runoff outlook are possible, but at this stage would require extremely wet or cool conditions to make a significant impact on seasonal flood risk by either accumulating more snow, or delaying the melt season.