The April snow survey and water supply bulletin from the BC River Forecast Centre shows a much diminished snow pack across the province.
Snow basin indices for April 1st, 2019 range from a low of 47% of normal in the Northwest to a high of 94% in the Upper Fraser West (Table 1 and Figure 1) with the average of all snow measurements across the province calculated to be 79% of normal, the report says. A well-below normal snowpack (<60% of normal) is present in the Stikine, Northwest and Skagit. A below normal snowpack (60-80% of normal) exists in the Liard, Skeena-Nass, Nechako, Central Coast, South Coast, Lower Fraser, Vancouver Island, Similkameen, Nicola, Okanagan, South Thompson, Boundary and East Kootenay. The Esat Kootenay snow pack is at 77 per cent of normal.
The rest of the province has slightly below normal to normal snowpack (80-95% of normal). There are no regions in the province with normal or above normal snowpacks.
March was a very dry month across the province, with most areas receiving less than 25 mm of precipitation.
Snow accumulation has been dominated by persistent weather patterns so far this season. Most of this year’s snowpack built up rapidly over a five to six-week period during early December to early-January. Weather through February was dominated by Arctic air across the province, with extremely cold temperatures and limited snow accumulation. This pattern has continued into the beginning of March. Extremely dry weather through March led to very little snow accumulation through the month. In low and mid-elevations (<1500m), hot weather led to snowpack ripening and early season snowmelt. Most basins dropped by 5 to 15% relative to normal compared to March 1 due to dry conditions (and limited accumulation), and in some sites early snowmelt.
The report says that annual snow accumulation in British Columbia usually reaches maximum levels in mid-April, therefore the April survey usually provides a good snapshot of the overall annual snowpack that will provide river runoff for the freshet season.
Given the below normal numbers, there is no indication of any elevated flood risk, however snow is not the only aspect to seasonal flooding. Spring weather conditions will also have an affect.
The report says that it is important to note that precipitation poses a real flood risk through the spring even with limited snowpack.