Water Supply Outlook for Alberta

January 2005

Mountain Snowpack

Snow accumulations in the mountains as of January 1, 2005 are generally below average to average for this time of the year. 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 40 to 50% of the seasonal total.

There were a limited number of snow course measurements taken at the end of December. More comprehensive measurements of mountain snowpack begin at the end of January.

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 37 to 85% of average for this time of year (Table 1). Snow accumulations are lower than those observed in December 2004 and generally similar to those measured in December 2002. The Many Glacier snow pillow in the St. Mary River basin ranks second lowest in 29 years of record, however measurements at higher elevations in the rest of the Oldman River basin show below average snowpacks. Winter precipitation at Many Glacier has been much below normal, but at the other two stations in the St. Mary River basin, winter precipitation has been below normal to normal.

Seven snow courses and an automated snow pillow reading were measured at the end of December in the Bow River basin, with values ranging from 80 to 112% of average (Table 2). Snow accumulations are near average for this time of year, ranking from ninth to twelfth lowest in up to 23 years of record, and are very similar to those measured last year at this time.

Two snow pillows in the Red Deer River basin show accumulations of 93 and 120% of average on January 1, 2005, which is average to above average for this time of year (Table 3). Snow accumulations rank ninth and twelfth lowest in 19 years of record, and are somewhat similar to those observed last year at this time.

No snow course measurements were made in the upper North Saskatchewan or Athabasca River basins this month, however the Limestone pillow is near the divide between the Red Deer and North Saskatchewan (Clearwater) River basins. Snow accumulation at this one location is above average for this time of year.

Snowpack in the upper Peace River basin in British Columbia is generally above average, as seen in the B.C. Snowpack and Water Supply Outlook (http://wlapwww.gov.bc.ca/rfc/river_forecast/bulletin.htm#Northeast).

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

Satellite estimation of plains snowpack as of January 1, 2005 suggests below average to average snowpack in most areas of Alberta (Figure 1). Despite below to much below normal winter precipitation to date, cold temperatures have resulted in snowfall staying on the ground rather than melting or evaporating. Weekly updates to this satellite map are available on the Meteorological Survey of Canada website . 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