Snowfall varied across Montana in March, but on the heels of heavy snow through the winter, the state’s major river basins remain well above normal going into warmer months ahead.
“One thing is for sure; it’s been a snowy winter across the state of Montana,” said Lucas Zukiewicz, NRCS water supply specialist for Montana, “and there’s still more to come.”
In February, records were set for both monthly totals for snowfall, and for total snowpack accumulation. That kept several snowpack measuring locations at record highs for April 1. Ten measuring sites were the highest on record for this date, and 12 measurement locations were the second highest on record. These sites can be found in the mountains that feed the upper Yellowstone, upper Clark Fork and Missouri river basins, where snowfall has been abundant throughout the winter months.
“Although not record-setting like these regions, the snowpack in other river basins across the state is well above normal for this time of year,” Zukiewicz said.
March snowfall came in near average for much of the state with a few exceptions. Southwest Montana saw continued above-average snowfall while the lower Clark Fork was the lone area well below for precipitation at 69 percent.
For the water year, all major basins were a third or more above normal. The Columbia at 137 percent, the Missouri at 133 percent and the Yellowstone at 135 percent mean this year may go down as one of the biggest snow years on record for some parts of the state.
The high snowpack is prompting questions on how it compares to other memorable snowpack years, Zukiewicz continued.
“1972, 1997, 2011 and 2014 were all big winters across the state, and many are wondering how this year compares,” he said. “So far, the only snowpack that has topped all other water years for peak snow water contained in the snowpack is the area near Cooke City which feeds the Clark’s Fork River of the Yellowstone River.”
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For the most part, the snowpack in the rest of the state hasn’t reached the levels of 1997, 2011 and 2014.
“During those years, snowpack peaked at the beginning of May to early June. For now, it looks like there is still a lot of winter left to come and this year could break more records if it keeps going.” Zukiewicz said.
Long-range predictions by the National Weather Service continue to forecast above average precipitation and below average temperatures through the end of April.
Due to the abundant snowfall, many measurement locations have already reached, or exceeded, the normal amount of snow water that is typically contained in the snowpack before runoff occurs. The totals all but assure at least normal surface water supply this spring and summer, Zukiewicz said.
Long-duration streamflow forecasts issued for the April 1 – July 31 period are well above average for most stream gages in the state, and could approach record levels this spring and summer at the stream gage at Belfry, located along Clark’s Fork of the Yellowstone.
“Having a big snowpack is a double-edged sword,” Zukiewicz said. “You know there will be plenty of snowpack to feed the rivers, which is typically great news, but the uncertainty of how and when it will come out can keep you up at night.”
April got off to a snowy start in much of the state with several inches of valley snow and higher accumulations in the mountains. Despite higher accumulations reported in the Helena area, official measurements were far from daily records, according to the National Weather Service in Great Falls.
The coming month will be important in determining how much water is available in the snowpack for runoff this spring, and the day-to-day and week-by-week weather patterns during May and June will determine the timing and volumes of water in Montana.