The weather has seemed to have forgotten that the calendar has changed from winter to spring during recent weeks and continues to deposit more snow across the crop regions of the Canadian Prairies. Not only have winter snow totals gotten very high, snow depths and the water stored in the snow on the ground have become high. The snow stored in the snow cover is known as snow water equivalent or SWE.
SWE is important to know during this time of year to help determine flood potential. During the winter and early spring, snow continues to build up on the ground if it stays cold enough but tends to continue to compact as new snow falls on old snow, pressing it down some. A few milder days thrown into the mix also help to compact the snow into a consistency known as corn snow by this time of year. Corn snow contains high levels of water content, sometimes as high as a 3-to-1 ratio.
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Snowfall totals thus far this season from data obtained from Environment Canada show percentages of normal of 124%, 186%, and 132% for Alberta, Saskatchewan, and Manitoba, respectively, for about 25 stations located throughout the main crop areas. Regina, Saskatchewan, has seen 228 cm (90 in) of snow this season, which is 232% of normal.
Since the winter as a whole has been cold for eastern areas and March has been very cold for nearly all areas, much of the winter snowfall is still on the ground, except for southern Alberta where milder temperatures have melted much of the snow cover recently.
As of April 1 snow depths were still 65 cm (26 in) at Lynn Lake, Manitoba, vs. a normal of 6 cm (3 in). Regina chimed in with 62 cm (24 in) and normally there is still only 5 cm (2 in) left by this time of year. The story is much the same across most of the Prairie cropland with very deep snow totals for early April which also contain lots of water.
SWE totals supplied by Environment Canada show a large area of 120 mm (4.7 inches) or greater of frozen water through east-central Saskatchewan as well as through the northern portion of the Alberta cropland. Nearly all of the remainder of the crop regions of Manitoba, Saskatchewan, and central and northern Alberta show water content of the snow at 90 mm (3.5 inches) or greater as of April 1.
The flood potential for the region is very high this spring and if a period of much warmer weather arrives soon along with rainfall we could see widespread flooding of rivers and streams throughout the region. Snow depths and SWE are also high through portions of Montana and North Dakota where some of the rivers originate that flow through the Prairies.
In the near term we should not see any flooding because of all things more snow and very cold weather are in the forecast during the next week or so. Temperatures are expected to continue to be too cold to begin any significant meltdown of the snow pack during the next week or so.
Doug Webster can be reached at firstname.lastname@example.org