Scattered rain and snow showers last month brought modest gains to Montana’s summer water supply outlook. However, the forecast in most locations remains below normal.
According to the Natural Resources Conservation Service in Bozeman, wet, cool May weather increased snowpack in most basins. But snowpack remained well below normal for most of the winter, and in several cases was the lowest on record. That means Montana’s short term summer streamflow forecasts have improved slightly, but more precipitation is needed to bolster the long term outlook.
The greatest improvements occurred in the Powder and Tongue basins where forecasted streamflow volume for May through July jumped from about 65-75% of normal to 120-140% of normal through next month.
The Yellowstone, Gallatin, Madison, and Flathead basins have a lot of snow remaining at the highest elevations. Those areas are now forecast to have about 80-90% of normal streamflow through July.
The Jefferson, Sun, Teton, Marias, Upper Clark Fork, and Blackfoot are only forecast to have about 50-60% normal streamflow through next month.
