Water Supply Outlook for Alberta

May 2004

Mountain Snowpack

Snow accumulations in the mountains as of May 1, 2004 are generally much-below-average in the Oldman, Highwood/Kananaskis, Red Deer, North Saskatchewan, Athabasca and Smoky River basins, and below-average in the Bow River basin for this time of the year (Table 1). The mountain snowpack is an important source of water supply to reservoirs in the province. Mountain snowmelt is occurring about a month ahead of normal, and as a result several locations have record or near-record low amounts of snow left for this time of year. Typically the peak snowmelt runoff from the mountain areas occurs in late May or June.

Twelve snow courses were measured at the end of April in the Oldman River basin (Table 2). This remaining snowpack is much-below-average for this time of year, with values ranging from 15 to 85% of average.

Fourteen snow courses were taken at the end of April in the Bow River basin, with values ranging from 43 to 93% of average (Table 3). Snowpack measurements are generally much-below-average in the southern half of the basin and below-average in the northern half. Snow accumulations are generally lower than last April, much lower than those recorded in April 2002, and much higher than the near record lows observed on April 1 of 2001.

Four snow courses were measured in the Red Deer River basin on May 1, with values ranging from 57 to 89% of average at three mountain sites, which is much-below-average for this time of year. One snow course in the foothills measured 8% of average. Six snow course measurements were made in the upper North Saskatchewan River basin, ranging from 0 to 86% of average, which is much-below-average for this time of year. Two snow course measurements were made in the upper Athabasca River basin, at 34 and 68% of average, which is much-below-average for this time of year. Red Deer, North Saskatchewan and Athabasca snow course data is available in Table 4. Snow accumulation during March was generally below-average to much-below-average in the Athabasca and North Saskatchewan River basins, and near-average in the Red Deer.

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