You may have noticed a whole bunch of “not availables” in the precipitation portion of the weather summary on page 87 of the Jan. 24 Western Producer.
It’s not something we wanted to do, but the percent of normal part of the weather summary just didn’t look quite right in the Jan. 17 edition.
Everyone is likely familiar with the concept that the “millimetres of precipitation” portion refers to the amount of water contained in the snow. It does not reflect, at least not directly, the number of centimetres that have fallen.
Even though the millimetres reflect the moisture held within the snow, the numbers seemed a little off. For example, Swift Current, Sask., was showing seven percent of normal. The Regina area, which by all accounts is seeing record snowfall this year, showed just 24 percent of normal. Only Prince Albert, Sask., was even close to normal, at 91 percent.
It is certainly the case that snow generally holds less water than one might think. At Crop Production Week in early January, Drew Lerner of World Weather Inc. said that despite the considerable amount of snow, in some places only two to six-tenths of an inch, or a maximum 15 mm of water, lurk within.
But the averages still seemed a little out of whack. Measuring water in snow is difficult and inaccurate, according to those who attempt it. If the wind is howling, the snow is blown around and misses the gauges that collect and then melt the white stuff.
As weather page guru Michelle Houlden (our art director) wrote two years ago, moisture content can vary widely from place to place or storm to storm.
This is why the Environment Canada weather reporting stations melt the snow and report the moisture as rainfall equivalent. Whether fluffy or heavy, you get an apples-to-apples comparison when all the snow becomes water, she pointed out.
One millimetre of precipitation is roughly equivalent to one centimetre of snowfall.
Agriculture Canada thinks it has solved the problem by using a number of tools to more accurately estimate the amount of moisture and the percent of normal. They did a complete re-audit of prairie weather conditions from Nov. 1 to the present, and what you’ll see on the weather page is the result.
It looks much closer to reality to me. See if you agree.