By NRCS Montana

BOZEMAN, Mont., March 6, 2024 –Following a slow start to winter, recent precipitation has been welcomed across Montana. “February kicked off with a region wide winter storm that brought one to two inches of precipitation to the region, and while there were a couple periods of warm and sunny weather, precipitation was relatively consistent last month,” said Eric Larson, USDA Natural Resources Conservation Service (NRCS) Water Supply Specialist. Precipitation totals for the month of February were as high as 150-200% of normal at various SNOTEL sites in Montana. Overall, basin wide precipitation ranged from about 110% of normal in Bitterroot and Lower Clark Fork to 170% in the Upper Missouri. The northern Bighorn Mountains were the exception receiving slightly below normal precipitation last month.

“The good news is widespread precipitation brought an increase in snowpack percentages in all of Montana’s river basins from last month,” said Larson. The largest increase occurred in the Upper Clark Fork and Upper Missouri River basins which improved from about 40% to 70% of normal snowpack conditions. As of March 1, snowpack percentages are about 65-75% of normal across the state. The Rocky Mountain Front snowpack has improved, but overall is the lowest percentage at about 50% of normal. The Bighorn River basin wide snowpack is about 90% of normal which is higher than the rest of the region because of the snowpack in the southern Absaroka and Wind River Range.

Other good news is that the first week of March has brought additional precipitation to the region. Several inches of snow water equivalent have accumulated at upper mountain elevations since March 1.

“Monthly snowpack percentages are derived from a combination of data from automated SNOTEL sites and manually measured snow courses, and don’t reflect the most recent storm,” said Larson.

The snowpack has continued to improve during the first days of March, but widespread snowpack deficits still exist. High elevation SNOTEL sites across Montana were still 10-12 inches of snow water equivalent behind normal on March 1. Recent precipitation has only begun to make a dent in the upper elevation snowpack deficit, but lower mountain elevation conditions are starting to look better.

With one to two months remaining in the normal snowpack accumulation season, more snow is needed. The snowpack at most SNOTEL sites is only about 50-60% of normal peak seasonal levels, which ideally occur mid-April to mid-May. “March, April, and May can be a very active time of the year for winter weather in Montana, which is good because winter weather needs to continue for a couple more months,” said Larson.

In 2014, 2017, and 2018, March and April brought more than normal snow accumulation.

In 2015, 2020, and 2021, March and April brought less than normal snow accumulation. A normal amount of precipitation over the next couple months would be helpful, but above normal precipitation would be better. A return of the warm and sunny weather experienced earlier this winter would result in a well below normal snowpack when it matters most. Hopefully the recent snowy weather is a sign of what is ahead.

Water supply forecasts are published in the March 1 Water Supply Outlook Report and provide an initial outlook of what spring and summer snowmelt might entail this year. “The recently published forecasts trend with water year precipitation and the ensuing snowpack. Given both are currently below normal in most locations, so are most forecasts,” said Larson. April-July streamflows are forecasted to be about 60-80% of normal in Montana.

However, forecasts are near to above normal in a couple pockets of the Pend Oreille, Kootenai, and Bighorn River basins where water year precipitation has been closer to normal. Forecasts published on April 1 and May 1 generally provide a better indication of what the upcoming season will bring.

While a full recovery to 100% of normal snowpack would be welcomed, below normal snowpack conditions on May 1 could be supplemented by above normal spring and summer precipitation if snow deficits aren’t too large this spring.

A full report of conditions on March 1 can be found in the monthly Water Supply Outlook Report available on the Montana Snow Survey website. In addition, real-time snow survey data can be found at nrcs.usda.gov/montana/snow-survey.