Montana Snow Levels Vary Widely
Even though storms in May added 17 percent more snowpack on average throughout Montana, the Bitterroot River drainage snow courses were 8 percent lower at the end of the month.
The monthly Natural Resources Conservation Service report June 1st showed snowpack increasing as much 32 percent in some snowcourses, and incredible 140 percent increase in the St and Milk River drainages in the north part of the state.
The snowpack experienced an rapid melt-rate in April with a couple of weeklong heatwaves, which also caused some minor flooding in the Bitterroot. But storms that have come through since then have brought not rain, but more snow to the higher elevations. For instance, with snowpack at 133 percent of average, the Flathead River has experienced some minor flooding recently.
Statewide, about 30 percent of the snowpack remains in the mountains, due, in part, to the Memorial weekend storms. Water Supply Specialist Brian Domonkos said, “…snowpack totals are above average in the northern and central two thirds of the state, while the southern third, altough improved, is still below average.”
What does that mean for streamflow through the summer?Domonkis said the forecasts have not changed much, and many streams have already experienced peak runoff.
Assuming normal moisture and runoff in June and July, the Bitterroot River streamflow will be 88 percent of average.