Water Supply Outlook for Alberta

June 2003

Mountain Snowpack

Mountain snowmelt is well underway in Alberta. Remaining mountain snow accumulations as of June 1, 2003 are generally average for this time of year, except in parts of the Red Deer River basin where much-above-average snowpacks remain. Seventeen of twenty snow course measurements taken at the end of May range from 53 to 117% of average. The mountain snowpack is an important source of water supply to reservoirs in the province. Typically the peak snowmelt runoff from the mountain areas occurs in late May or June.

Three snow course measurements were taken at the end of May in the Oldman River basin. The snowpack is average for this time of year, ranging from 59 to 109% of average (Table 1).

Thirteen snow course meaurements were done at the end of May in the Bow River basin. Snowpacks are generally normal for this time of year, and range from 53 to 129% of average (Table 2).

Four snow courses were performed in the Red Deer River basin at the end of May, with two showing average snowpack and two showing much-above-average snowpack remaining. Values range from 59% to 316% of average (Table 3).

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