Water Supply Outlook for Alberta

June 2006

Mountain Snowpack

Remaining snow accumulations in the mountains as of June 1, 2006 are generally better in the south than in the north (Table 1). Measured snowpacks are below average to average in the Oldman River basin, below average in the Elbow and Highwood River basins, and below average to much below average in the Upper Bow and Red Deer River basins. Warm weather during May accelerated mountain snowmelt this year and the bulk of the snowpacks have melted. Typically the peak snowmelt runoff from the mountain areas occurs in late May or June, however the peak snowmelt occurred in mid-May this year for most mountain fed streams. The mountain snowpack is an important source of water supply to reservoirs in the spring. Mountain streams are still receiving snowmelt contributions from higher elevations.

Three snow courses were taken at the end of May in the Oldman River basin. This remaining snowpack is below average to average, with values ranging from 21 to 91% of average for this time of year (Table 2). Two snow pillows located in the Waterton and St. Mary River basins are reporting average snowpack conditions.

Thirteen snow courses were taken at the end of May in the Bow River basin, with twelve values ranging from 7 to 83% of average and one lower elevation location recording zero snow left, which is common for this time of year (Table 3). Snow accumulations are generally below to much below average in upper Bow River basin and below average in the Kananaskis, Elbow and Highwood River basins.

Three snow course measurements were taken at the end of May in the Red Deer River Basin, with values ranging from 0 to 24% of average, which is generally below to much below average (Table 4).

Only one snow course measurement was taken in the North Saskatchewan River basin at the end of May, Limestone Ridge which is on the divide with the Red Deer River basin. As was the case nearly half the time over the 20 year record, zero snowpack was measured at this location at this time of year(Table 4). Since this location is at a low elevation relative to the headwaters of the North Saskatchewan River basin, it is likely not indicative of the mountain snowpack.

No snow courses were measured in the Athabasca River basin at the end of May. Two snow pillow readings in British Columbia but near the upper Athabasca River basin headwaters show the snowpack at 19 and 86% of average for this time of year.

Snowpack in the upper Peace River basin in British Columbia is generally average, as seen in the B.C. Snowpack and Water Supply Outlook (http://www.env.gov.bc.ca/rfc/river_forecast/asp_com.htm).

At twelve snow course sites, real-time snow accumulation can be monitored using snow pillows. Snow pillows can be viewed by choosing any mountainous southern basin, and snow data, in the two drop down menus at:


Snow water equivalent values on the snow pillow may or may not match the snow course value at a particular location. While snow pillow data is very valuable information, the quantity of snow on the pillow is only representative of the accumulation at that specific spot. A snow course survey is measured at numerous spots and provides a more representative value of snow in the area. In some locations, there can be considerable difference between the snow pillow and snow course values. Factors such as wind and exposure of the site can cause the snow pillow values to be significantly different from the snow course survey. The snow pillow graphs on our website show the daily average snow water equivalent. The monthly snow survey is the average of all measurements conducted within five days of the end of the month. Also, where snow pillow and snow course measurements are available for the same site, snow pillow records tend to be much shorter (10-15 years) in length compared to the snow course sites. As a result, the difference in the average value between the snow pillow and the snow course can be attributed to snow water equivalent being derived two different ways (physically measured compared to an instrument reading), site location and length of data record. In some cases, the values can deviate by 10-20%. Therefore, while snow pillows are excellent for analyzing trends and for monitoring accumulation between snow surveys, snow course values should always be used when considering the quantity of snow at a particular location as they best represent that area.

Click here to see a map of snow course locations

For technical enquires about this web page please contact Alberta Environment - Environmental Management Water Management Operations Branch at AENV-WebWS@gov.ab.ca