February’s storms helped push Montana’s snowpack up to normal, but March needs to follow suit to help rivers stay full through the summer.
After a relatively dry start to the year led to a below average snowpack in January, storms finally appeared in early February and the snow started to pile up. Four weeks later, the state had received 180 percent of the average precipitation received during February over the past 30 years, according to the Natural Resources Conservation Service water supply report.
“It seemed like every time a storm was moving out, another one was lined up to come in,” Lucas Zukiewicz, NRCS water supply specialist, said Thursday.
The result is that statewide, the snowpack water content finally topped the 30-year average and is now 110 percent of average.
In western Montana, the only snowpack that remains below average, at about 92 percent, is in the Flathead and Kootenai river basins, but that’s better than the 82 percent they had at the start of February.
Snowpack in the Bitterroot and lower Clark Fork regions is about average, while it’s 116 percent above average in the Clark Fork basin east of Missoula.
The Madison basin is leading the state with the snowpack at 130 percent of average, thanks to pockets of moisture that moved up from the southwest. During the past decade, the Madison and Jefferson basins between Bozeman and Dillon have regularly ended the winter with below average snowpack.
“This month was the perfect setup, with cold air in place and abundant moisture coming from the Pacific that collided with it,” said Zukiewicz. “Sixteen NRCS snowpack measurement locations set new records for February snowfall in central and southern Montana, and an additional 13 sites recorded the second-highest monthly totals.”
The Kootenai basin in the northwestern corner of the state is still lagging behind, even though it received above normal February precipitation. Even so, it has only 82 percent of the overall precipitation it should have for the year, leaving it in an “abnormally dry” drought category. So at this point, early predictions for the Kootenai have summer streamflows at only 80 to 85 percent of normal.
The predictions for the Clark Fork River is for normal to slightly above normal flows until the river hits Plains below where it joins with the Flathead River. There, it drops slightly due to slightly below average flows predicted from the Flathead River.
For now, the Bitterroot River is also predicted to have normal to slightly below normal flows.
But everything depends on what happens in March.
February’s streamflow predictions assume that average levels of precipitation will fall during March. If more snow or rain falls, so much the better for the rivers, irrigators, fish and fishermen. But if March is dry, the state’s water reserve could fall below normal again. Snowpack typically peaks in early April west of the Continental Divide and a week or two later on the east side.
“We have another month or two of snow accumulation to go, and it can be an important couple of months to top things off before we start to see snowmelt and runoff. We’re back on the right track, so let’s hope that the snow keeps flying and the above average temperatures don’t show back up before then,” said Zukiewicz.
Contact reporter Laura Lundquist at firstname.lastname@example.org.