Water Supply Outlook for Alberta

March 2002

Mountain Snowpack

Snow accumulation in the mountains as of March 1, 2002 are near average for this time of the year with the exception of the headwaters of the Oldman River basin, which have below-average to average accumulations and the Highwood and Kananaskis headwaters, which are above-average for this time of the year (Table 1). The mountain snowpack is an important source of water supply to reservoirs in the province. Typically the accumulation of snow at this time of the year accounts for nearly three-quarters of the seasonal total.

Six snow course measurements were made in the Oldman River basin during the last week of February, with values ranging from 84 to 102% of average (Table 2). Above-average accumulation in February brought many of the higher elevation stations to near average values for this time of the year. Snow accumulations are significantly above values observed last year at this time. While the higher elevations of the basin have near average accumulations, areas below 6000 feet remain below-average despite a snowstorm that brought significant snowfall to most areas at the end of February. More snowfall is needed in these areas due to the very low soil moisture conditions.

Snow pillows in the Oldman River basin are indicating accumulations near or slightly above-average for this time of the year. While snow pillow data is very valuable information, the quantity of snow on the pillow is only representative of the accumulation at that point. 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. A snow course survey is measured at numerous points and provides a more representative value of snow at that location. Snow pillows are excellent for analyzing trends and for monitoring accumulation between snow surveys however when considering the quantity of snow, the snow course values should always be used.

Sixteen snow course measurements were made at the end of February in the Bow River basin with values ranging from 86 to 127% of average (Table 3). Snow accumulations were above-average during February, particularly in the Highwood and Kananaskis headwaters. Current snow accumulations in the Bow River basin are one and a half times the seasonal maximum recorded last year. All snow surveys measured above 6000 feet indicate snow accumulations are average or above-average. The three sites located below 6000 feet (Bow River, Chateau Lawn and Pipestone Upper) indicate below-average accumulations and were the lowest in the basin in terms of percentage.

Ten snow course measurements were completed in the headwaters of the Red Deer, North Saskatchewan and Athabasca River basins during the last week of February (Table 4). Snow accumulations ranged from 79 to 148% of average at the ten sites. Four of the snow surveys were completed in the Red Deer River headwaters showing above-average snow accumulations. Accumulations in the North Saskatchewan and Athabasca River headwaters are near average for this time of the year.

Snow course measurements are completed monthly. At twelve of the snow course sites, real-time snow accumulation can be monitored using snow pillows. The snow pillow plots can be found on the department website in the Weekly River Report.

Plains Snowpack

As of March 1, 2002, plains snowpack is below-average to much-below-average along the eastern portions of the province and is currently less than what was on the ground last year at this time. In western regions, including Grande Prairie, Sundre, Calgary and Pincher Creek areas, have near average snowpack with the exception of the Edson-Rocky Mountain House area, which has much-below-average snowpack.

In the northern half of the province, most areas have below-average snowpack, including the Edmonton, Slave Lake, Cold Lake, High Level and Fort Chipewyan areas. Snowpack is near average in the Grande Prairie and Peace River areas and is significantly higher when compared to last year at this time.

Significant snowfall occurred from March 3 to 6, 2002 in the plains area. The extent of the snowfall was from Grande Prairie to Medicine Hat and brought significant precipitation to these areas (Figure 1). Grande Prairie and Edson areas received 10 to 15 mm of precipitation while areas around Red Deer received anywhere from 5 to 20 mm. The highest amounts were in the Pincher Creek and Lethbridge area, where between 10 to 25 mm of precipitation was recorded which accounts for nearly half of the normal March precipitation. Snow course measurements will be made during the last week of March and be reported on in the April Water Supply Outlook. To monitor snow accumulations in the plains areas during the month, a map showing snow water equivalent of Plains area snowpack is available from the Environment Canada website located at: http://www.msc-smc.ec.gc.ca/ccrp/SNOW/snow_swe.html.

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