Christmas snow was the gift Montana needed to possibly avoid drought this summer.
This water year – which runs from October to September – held true to a trend caused by climate change: winter weather comes later each year. Snow didn’t begin piling up until one to three weeks later than normal, according to the U.S. Natural Resources Conservation Service January Water Supply Report.
After a warm, dry November, Montana’s snowpack was low to nonexistent as December started. Normally white-topped ranges such as the Crazy or Tobacco Root mountains were still dark and bare, even though Montana had had an unusually wet October.
By the end of October, some areas in northwestern Montana had received about 20 inches of precipitation where they normally get between 4 and 8 inches. The entire state is looking good as far as average precipitation for the year, but it was too warm in November for the moisture to stick around as snow.
Fortunately, as the days continued to shorten, temperatures dipped and snow moved in. December has been accompanied by a normal amount of snowfall, which helped snowpack recover somewhat. Overall, as of Jan. 1, the state has 87 percent of its normal snowpack for this time of year.
The Missouri River basin is the worst off with just 80 percent of its normal snowpack, due to the Smith-Judith-Musselshell basins receiving only 62 percent of their average snowpack. Last year, the Smith-Judith-Musselshell also started off slow but ended up with the most snow in the Missouri basin by May.
The Yellowstone basin is looking the best in the state with about average snowpack, while the lower Yellowstone has just a bit more.
Remember, however, the NRCS has adjusted the snowpack average to reflect snow measurements during the years 1980-2010. Since snow amounts have been decreasing over the past 50 years, if the NRCS used the average calculated over a longer period of time, Montana’s snowpack would be maybe only 70 to 75 percent of average.
The reason Montanans want at least average snowpack if not more is because it translates into healthy stream levels in the summer. The deeper the snowpack, the longer it takes to melt normally, and the longer it feeds the alpine streams that flow into the valley rivers. If the snow isn’t very deep, rivers will dwindle, fish will struggle to live and irrigated crops will wither.
So even though it’s a bit early for forecasts, the NRCS predicts that river flows should be good in the Yellowstone River as long as the Yellowstone basin receives average snowfall throughout the rest of the winter. Only the Shields River looks like it could run lower than normal.
Most of the Missouri River basin should flow well except the Missouri River below Fort Peck Dam, the Jefferson River near Twin Bridges, Three Forks and the Clark Canyon inflow, which may be only 85 percent of their normal flow between April and July.
Not surprisingly, the Smith-Judith-Musselshell has a poor forecast for now, with the Musselshell River flowing at only 50 percent of average near Harlowton and less than 30 percent near Roundup.
However, three to four months remain when the snow can continue to build. But, if the climate-change trend holds true, spring will come earlier and April’s snows may not contribute much.
So the next time you hear someone griping about the snow and cold, ask them if they like to play in the rivers in the summer.