Snow simulations predict future changes in rain-on-snow events across the upper Gallatin River watershed, a Greater Yellowstone Ecosystem headwater system

Journal of Hydrology: Regional Studies
By: , and 

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Abstract

Study region: The upper Gallatin River watershed, an alpine headwater system in the Greater Yellowstone Ecosystem, in Wyoming and Montana.

Study focus: As global and regional air temperatures rise, mountain headwaters across the Greater Yellowstone Ecosystem (GYE) are projected to see more precipitation falling as rain. While the hydrologic effects of this snow-to-rain transition depends on a variety of factors, it can lead to an increased occurrence of rain-on-snow (RoS) events. To investigate these changes, we used high-resolution (30 m) SnowModel simulations of the upper Gallatin River watershed. Simulations were run for 2001-2013 using two scenarios: (1) historical meteorology as control and (2) pseudo global warming (PGW) where control air temperature and precipitation conditions were perturbed to represent mean end-of-century conditions under a high-emissions scenario.

New hydrological insights for the region: SnowModel outputs show that changes in PGW precipitation and snow accumulation varied with elevation. Warmer air temperatures at low elevations (< 2,500 m) led to less snow accumulation and less precipitation falling as snow. Colder baseline air temperatures for elevations above 2,500 meters (m) resulted in minor reductions in winter snowfall fraction. For PGW simulations, spring (April-June) months were rainier, and elevations above 2,500 m experienced more RoS events. Snowpacks between 2,500-3,100 m generated more snowmelt during RoS events, which was reflected in the watershed average. More high-intensity melt events can affect aquatic habitat, water quality, and the accuracy of streamflow forecasts across the region.

Suggested Citation

Newcomb, S.K., Barnhart, T., Heldmyer, A.J., and Storb, M.B., 2026, Snow simulations predict future changes in rain-on-snow events across the upper Gallatin River watershed, a Greater Yellowstone Ecosystem headwater system: Journal of Hydrology: Regional Studies, no. 64, 103253, 15 p., https://doi.org/10.1016/j.ejrh.2026.103253.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Snow simulations predict future changes in rain-on-snow events across the upper Gallatin River watershed, a Greater Yellowstone Ecosystem headwater system
Series title Journal of Hydrology: Regional Studies
DOI 10.1016/j.ejrh.2026.103253
Issue 64
Year Published 2026
Language English
Publisher Elsevier
Contributing office(s) WY-MT Water Science Center
Description 103253, 15 p.
Country United States
State Montana, Wyoming
Other Geospatial Gallatin River watershed, Yellowstone National Park
Additional publication details