Water Supply Outlook for Alberta

January 2007

Mountain Snowpack

Snow accumulations in the mountains as of January 1, 2007 are generally average for this time of the year in the Oldman, Red Deer, and Elbow River basins, and above to much above average in the remainder of the Bow River basin. 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 two-fifths of the seasonal total.

One snow course and four automated snow pillow readings were taken at the end of December in the Oldman River basin, with values ranging from 84 to 115% of average for this time of year. The three locations in the Canadian portion of the basin have snowpack ranging from average to above average, and the two in the United States are below average to average (Table 1). Snow accumulations are much higher than at this time last year.

Seven snow courses and one automated snow pillow were measured at the end of December in the Bow River basin, with values ranging from 100 to 136% of average (Table 2). The one snow course in the Elbow River basin has average snowpack, slightly lower than last year at this time. In the rest of the Bow River basin, measured snow accumulations are generally above to much above average and much higher than values recorded for January 1, 2006.

Two snow pillows in the Red Deer River basin show snowpack ranging from 78 to 151% of average as of January 1, 2007 (Table 3). One location's snowpack is below average and lower than at this time last year, and the other's is much above average and much higher than last year at this time.

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 snowpacks are average to above average, as seen in the snow pillow plots available at: http://www.env.gov.bc.ca/rfc/river_forecast/snowp_map.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

Plains Snowpack

As of January 1, 2007, estimation of plains snowpack from Environment Canada's satellite data (Figure 1) and Alberta Agriculture's moisture budget model (Figure 2) show below normal snowpack conditions in the southern plains, while central plains range from normal to much above normal and northern plains range from below normal to normal. Precipitation in northern Alberta for the past 4 months has been below to much below average, so northern snowpack estimates may be a bit high. More detailed information on plains area snowpack will appear in the March Water Supply Outlook as snow course measurements will be conducted at the end of February.

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