Snowpack recovery improves Montana streamflow forecasts

by Lake County Leader
March 12, 2020 9:29 AM

State hydrologists are encouraged by the above-average snowpack that has stacked up in Montana’s mountain terrain this winter despite temperatures that have trended well above normal.

The mountain snowpack in all of the major river basins across Western Montana has recovered from a slow start to winter and is at or above normal for this time of year.

“January and February snowfall took the dismal snowpack totals reported on January 1 along the Montana/Idaho border and improved snowpack to near to above normal on March 1,” said Lucas Zukiewicz, Natural Resources Conservation Service water supply specialist for Montana. “This is great news for water users as we approach spring and summer.”

Snowpack totals in all river basins across Montana are now near to above normal for March 1.

In fact, new records were set for February snowfall at seven mountain SNOTEL sites in southern and central Montana, according to a hydrology outlook issued March 5.

At this point in the winter, Zukiewicz noted, around 75 to 85 percent of the seasonal peak snowpack has typically accumulated at mountain locations, giving forecasters a good idea of how snowmelt will affect water supply during spring and summer.

As of March 1, the Flathead River Basin’s snow-water equivalent was at 120 percent of normal and the Kootenai Basin was at 104 percent of normal. The Upper Clark Fork Basin registered at 115 percent of normal, while the Lower Clark Fork was at 105 percent.

“Streamflow prospects for spring and summer look to be near to slightly above average at this time due to the healthy snowpack totals we have in the mountains,” Zukiewicz said, adding that precipitation and temperatures during the next three months will play a critical role.

“Even though spring starts on March 19, there is still typically a lot of winter left to come in the mountains, and the juicy months are on the horizon for some of our east of the Divide river basins. These months can make or break our spring and summer streamflows,” Zukiewicz said.

Long-range forecasts issued by NOAA’s Climate Prediction Center for the next two weeks (March 3-17) indicate better than normal chances of above average temperatures across the state and near to below normal precipitation. “While we’ve got more water than we typically have stored in the snowpack on March 1, I’ve learned from experience it’s never wise to assume we will be in the same shape come May 1,” Zukiewicz added.