Water Supply Outlook for Alberta

December 2008

Mountain Snowpack

Snow accumulations in the mountains as of December 1, 2008 are generally much below average for this time of year in the Oldman, Bow River and Red Deer River basins. Values rank among the five lowest in generally 20 to 30 years of record, at all but one location. The mountain snowpack is an important source of water supply to reservoirs in the spring. On average, the accumulation of snow at this time of the year accounts for nearly one-fifth of the seasonal total.

Three snow courses and two automated snow pillow readings were taken at the end of November in the Oldman River basin, with values ranging from 14 to 53% of average for this time of year, which is much below average (Table 1). Snow accumulations rank among the three lowest on record, which varies from 11 to 31 years depending on the site.

Eight snow courses were measured at the end of November in the Bow River basin, with values ranging from 27 to 77% of average for this time of year, which is generally much below average(Table 2). All but one of these snow accumulations ranked 3rd or 4th lowest on record. The average record length is 21 years. One station, Sunshine Village, has snowpack which is below average at 77% of average and 9th lowest in 26 years of record.

One snow pillow reading in the Red Deer River basin showed the snowpack at 47% of average on December 1, 2008, which is below to much below average and ranked 5th lowest in 26 years of record (Table 3).

No snow course measurements were made in the upper North Saskatchewan or Athabasca River basins this month. More comprehensive snow course measurements of basin snowpack begin at the end of January.

Four snow pillows in the upper Peace River basin in British Columbia indicate snowpack ranging from 109 to 154% of average, as seen in the snow pillow plots available at: http://www.env.gov.bc.ca/rfc/river_forecast/snowp_map.htm.

At thirteen snow course sites, real-time mountain snow accumulation can be monitored using snow pillows. Snow pillows can be viewed by choosing any mountainous southern basin or the Athabasca River 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

Plains Snowpack

Satellite estimation of plains snowpack as of December 1, 2008 shows a patchy snowpack in northern Alberta (Figure 1).

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