Snowpack Deficits Grow Across Montana After a Dry, Warm January

Well below normal January precipitation and unseasonably warm temperatures stalled Montana's snowpack accumulation last month.

"Most Montana basins are now reporting below normal snowpack. While some higher elevations are holding onto their snowpack reserves, mid elevation snowpack is falling behind, and low elevation snowpack is noticeably absent," said Florence Miller, USDA Natural Resources Conservation Service (NRCS) Hydrologist. "As of February 1, most major basins hold 65-90% of median snowpack, a 10-30% decrease from the January 1 medians. Snowpack in the Bears Paw Mountains is currently around 45% of median Snow Water Equivalent (SWE), while the Upper Yellowstone and Bighorn basins are the only basins in the state hovering around 100% of median SWE."

January precipitation was only 50-75% of median and temperatures remained largely above normal. Many areas across the state lost soil moisture with the dry January and minimal snow cover, causing drought conditions to increase. The snowpack continues to be denser than normal for this time of year due to the above normal temperatures seen in December and January.

Water-year-to-date precipitation remains well above normal (100-150% of median) statewide, thanks to a wet December. Higher elevation SNOTELs, where early precipitation fell as snow, accumulated snowpack surpluses during that period. However, January's lack of precipitation eroded those surpluses at all but the highest sites. Most SNOTEL and snow course stations across Montana are reporting a one- to five-inch deficit below normal SWE for this time of year, with a couple higher elevation pockets in the Cabinet and Swan Range nearing an eight-inch deficit. A few higher elevation stations have retained up to a five-inch surplus from the early winter precipitation. For example, in the Whitefish Range, the Stahl Peak SNOTEL at 6,040 feet is reporting 24.5 inches of SWE (111% of median). The lower elevation Grave Creek SNOTEL at 4,350 feet has only 4.4 inches of SWE (41% of median).

"Mid- to high-elevation snowpack is the main contributor to summer streamflow. How the lack of low elevation snow coverage will influence snowmelt driven runoff this year is yet to be determined. Official water supply forecasts will be available starting next month after more of the snowpack accumulation season has played out," explains Miller.

Montana's mountains typically reach peak snowpack between late March and early May. Conditions at that time will influence summer streamflow far more than this February 1 snapshot. Statewide, most SNOTELs are less than half of the way towards their normal peak snowpack. With two to three months remaining in the snowpack accumulation season, a return of winter and continued snowfall will be crucial to catch up current snowpack deficits. While current snowpack deficits can still be recovered, the larger they grow, and the shorter the time to catch up, the less likely full recovery becomes.

More Information

A full report of conditions on February 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.

For 90 years, NRCS has helped farmers, ranchers and forestland owners make investments in their operations and local communities to improve the quality of our air, water, soil, and wildlife habitat. NRCS uses the latest science and technology to help keep working lands working, boost agricultural economies, and increase the competitiveness of American agriculture. NRCS provides one-on-one, personalized advice and financial assistance and works with producers to help them reach their goals through voluntary, incentive-based conservation programs. For more information, visit nrcs.usda.gov.

Photo

Enroute to maintain sensors at the Divide SNOTEL site, an NRCS hydrologist avoids tufts of sagebrush that have yet to be buried under a winter snowpack. Snow accumulation stalled in January, while temperatures stayed unseasonably warm. Most basins are now reporting below normal snowpack, no longer padded by high elevation snowpack surpluses. On February 1, Divide SNOTEL reported 70% of median snow water equivalent (SWE), while 1000 ft lower and 15 miles away Short Creek SNOTEL reported 47% of median, mirroring the same elevational pattern as December. Snowpack at Divide usually peaks in late April. There is still time for the snowpack to recover.