By Don Urquhart, Times Chronicle
The Province’s latest snow and water supply data indicates that average mountain snowpack is near normal levels, and higher than last year, but warns the number masks significant regional differences such as the Okanagan at 58 per cent of normal is the lowest in recorded history.
While the provincial mountain snowpack is at 92 per cent of normal as of April 1 compared to last year’s average of 79 per cent, the Okanagan has only reached 58 per cent of normal with with others fairing worse like the Skagit valley at 26 per cent and Vancouver Island at 44 per cent.
The Snow Survey and Water Supply Bulletin by the River Forecast Centre notes that April 1 represents the benchmark survey for assessing seasonal hazards, as approximately 97 per cent of the annual snowpack has typically accumulated.
“In some basins, such as the Okanagan and Boundary, snowpack remains significantly below both normal and last year’s levels, increasing the likelihood of reduced streamflow and water supply challenges,” the bulletin read.
The Okanagan Snow Basin Indices (SBI) at 58 per cent of normal, represents the lowest April 1 value since at least 1980, when basin-scale indices were first calculated, highlighting “the severity of snowpack deficits in the region”.
It also noted that areas with below normal snowpack, particularly in the southern Interior and coastal regions, show early concerns for drought conditions potentially amplifying into spring and summer.
River Forecast Centre graphic
The provincial SBI ranged from a low of 26 per cent of normal for Skagit to a high of 136 per cent for the Nechako and Peace regions.
Ten snow stations measured all-time high snow water equipment (SWE) for April 1, while seven recorded all time low SWE. Of the seven, one was in Boundary (Big White at 61 per cent of normal) and four were in the Okanagan.
The Okanagan snow stations include:
- Greyback Reservoir – lowest in 9 years;
- Isintok Lake at 31 per cent of normal;
- Brenda Mine at 21 per cent of normal;
- Oyama Lake at 28 per cent of normal.
River Forecast Centre graphic
The bulletin noted that seasonal outlooks from Environment and Climate Change Canada (ECCC) indicate an increased likelihood of above normal temperatures across much of British Columbia for the April to June period.
Below normal runoff is forecast for several southern Interior systems, including Okanagan Lake (38-51 per cent of normal), Kalamalka-Wood Lake (20-45 per cent), Nicola Lake (41-62 per cent), and Nicola River (54-58 per cent), reflecting well below normal snowpack and antecedent conditions.
“These basins are expected to have reduced seasonal water supply and increased susceptibility to drought conditions through the spring and summer,” according to the bulletin. Using a new “ensemble streamflow prediction” model the Okanagan Lake is forecast to have inflows of between 43 and 64 per cent of normal.
