Water Supply Outlook for Alberta

April 2003

Mountain Snowpack

Mountain snow accumulations as of April 1, 2003 are generally below-average to much-below-average for this time of year. Twenty-eight of thirty-three snow course measurements taken at the end of March range from 68 to 90% of average (Table 1). Measurements in the foothills vary widely from much-above-normal to completely melted. Snowpacks range from third lowest to twenty-first lowest on record, for this time of year. The current snowpack is generally much lower than last year at this time but much higher than in 2001, which was the lowest on record in many areas. The mountain snowpack is an important source of water supply to reservoirs in the province. On average, the accumulation of snow for this time of the year is nearing the seasonal total in the Oldman River basin and is normally 80 to 95 % of the seasonal total in areas north of this basin.

Eight snow course measurements were taken at the end of March in the Oldman River basin. The snowpack is below-average to much-below-average for this time of year, ranging from 70 to 86% of average in the mountains (Table 2). The snow has all melted at the one foothills snow course location near Lee Creek. Mountain snowpacks have significantly improved, by generally 20%, due to much-above-normal snowfall during March. Snowpacks rank fourth to tenth lowest in up to 40 years of record and are approximately 50% better than the record-lows of 2001.

Fifteen snow course meaurements were done at the end of March in the Bow River basin. Snowpacks ranged from 68 to 89% of average, which is below-average to much-below-average for this time of year (Table 3). March snowfall improved the snowpack by about 20% of average. The April 1, 2003 snowpacks rank from fourth lowest to twenty-first lowest in up to 67 years of record. This year's snowpacks are much better than the record-lows of April 1, 2001, generally ranging from one-and-a-half times as large in the upper Bow River sub-basin to almost double the snow in the upper Highwood, Elbow, and Kananaskis River basins. Last year's snowpack was roughly 50% higher than this year's.

Ten snow courses were performed in the Red Deer, North Saskatchewan, and Athabasca River basins at the end of March. Snowpacks improved on average by 50% due to heavy March snowfall, but generally snowpacks are below-average in the upper North Sakatchewan and Red Deer River basins and below-average to much-below-average in the upper Athabasca River basin, ranging from 72% to 105% of average (Table 4). Snow conditions rank from third lowest to twenty-first lowest in up to 35 years of record and in the upper elevations are roughly 50% better than in 2001. Snowpack in the foothills of the Athabasca and North Saskatchewan River basins is quite variable, ranging from much-below-average to much-above-average. The Limestone snow course, in the foothills of the Red Deer River basin, remains much-above-average (149% of average) due to a localized snowfall in early October.

At twelve snow course sites, real-time snow accumulation can be monitored using snow pillows. Snow pillows can be viewed by choosing any 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