Mountain Snowpack

Snow accumulations in the mountains as of April 1, 2005 generally improve moving from south to north (Table 1). Measured snowpacks are much below average in the Oldman River basin, below to much below average in the Highwood - Kananaskis River headwaters, below average to average in the Bow River basin, above average in the Red Deer and Athabasca River basins, and average in the North Saskatchewan River basin for this time of the year. Snowpack in the upper Peace River basin, in British Columbia, is generally average to above average. 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 is nearing the seasonal total in the Oldman River basin and is normally 80 to 95 % of the seasonal total in mountain areas north of this basin.

Eight snow courses and two automated snow pillow readings were taken at the end of March in the Oldman River basin. Values range from 18 to 73% of average for this time of year (Table 2). Snowpacks at all elevations showed little improvement during the past month and remain much below average. Eight of the ten locations had snowpack ranking among the lowest three on record in up to fourty-two years of data. Record lows were measured at two of three locations below 5000 feet of elevation, one fewer than last month. Eight locations above 5000 feet of elevation had snowpacks ranging from 46 to 73% of average.

Fifteen snow courses and two automated snow pillow readings were measured at the end of March in the Bow River basin, with values ranging from 71 to 104% of average (Table 3). Snow accumulations are below average to average for this time of year upstream of Banff, similar to end of February, and generally below to much below average in the Elbow, Highwood, Kananaskis, Cascade and Spray River basins, a decrease from last month.

Seven snow course measurements in the Red Deer and North Saskatchewan River basins show accumulations ranging from 79 to 126% of average on April 1, 2005, and three snow course measurements in the Athabasca River basin range from 104 to 191% of average (Table 4). Snowpack is average for this time of year in the North Saskatchewan River basin, and above average in the Red Deer and Athabasca River basins. The Hinton snow course ranked highest in thirty-one years of record.

Snowpack in the upper Peace River basin in British Columbia is generally average to 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:

As of April 11, it is evident from the pillow data that melting of the mountain snowpack has started again in the upper Oldman River basin, which is normal for this time of year. Further snow course measurements will be conducted at the end of April.

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