“Warm temperatures and lack of precipitation over the last couple months have resulted in a bleak start to the seasonal snowpack in Montana and northern Wyoming river basins,” said Eric Larson, USDA Natural Resources Conservation Service (NRCS) water supply specialist.
Water year 2024 began with a mid-October snowstorm that brought about two to five inches of precipitation to parts of northern Wyoming and southern Montana. Totals from that storm were less across the rest of Montana, particularly in the northwest where river basins such as the Kootenai, Lower Clark Fork, Flathead and Saint Mary only received less than an inch of precipitation and less than half of their normal October precipitation.
“Precipitation was largely absent during November and December, except in northwest Montana which received reasonable precipitation during the first half of November and December,” said Larson.
Two-month precipitation in that region was about 75-100% of normal. Snow Telemetry (SNOTEL) Network sites in the northern Whitefish Mountain Range received about 130% of normal precipitation over the two months. Across the rest of the region, November and December precipitation was about 40-60% of normal, except in the Bighorn Mountains and Helena area where precipitation was about 35-45% of normal.
Water year precipitation currently ranges from about 55-80% of normal on the west side of the Continental Divide to about 100-115% of normal in the Bighorn, Powder and Tongue River basins, “which is only above normal because of the large mid-October storm,” said Larson.
Water year precipitation has been lowest in the Sun, Teton and Marias river basins at about 50% of normal. Central, southcentral and southwest Montana have received about 65-80% of normal precipitation since Oct. 1.
As of Jan, 1, Montana’s seasonal snowpack ranges from about 25% of normal in Sun, Teton and Marias river basins to about 75% of normal in the Bighorn, with most basins reporting less than 60% of normal snowpack conditions.
The maximum snow depth across the region is currently about 36-38 inches in Glacier and Yellowstone national parks and surrounding areas, which is about 10-12 inches of snow water equivalent and is 60-80% of normal. In addition, “about 110 of 175 NRCS snow stations measured on Jan. 1 are reporting their lowest or second lowest snowpack on record. Some of those records date back nearly 90 years,” said Larson.
There are three to four months remaining in the normal snowpack accumulation season. Current snowpack deficits are generally about two to four inches, with a couple exceptions at upper elevations in Montana where deficits are closer to seven to nine inches of snow water equivalent below normal.
“It would take a major change in what the last couple months brought for weather, but it’s still early and current deficits could be recovered in a couple large storms,” said Larson. Regardless winter weather needs to arrive soon. The further winter progresses with below normal precipitation, the more challenging it will become to make up from a lack of snow.
A full report of conditions on Jan. 1 can be found in the monthly Water Supply Outlook Report available on the Montana Snow Survey website at tinyurl.com/4et82rfe. — USDA
