Precipitation (30-year average) of Yellowstone Park, Wyoming, Montana, Idaho

The average annual precipitation was calculated from Snow Course (SC), Snow Survey Telemetry (SNOTEL), and Climate Stations (CLIM) data from the 30-year base period of 1961-1990. The standard for comparing climactic and hydrologic data is to use a 30-year period updated every 10 years. The annual precipitation at snow courses was estimated using the April 1 SWE (snow water equivalent) versus annual precipitation curve obtained from data at SNOTEL and CLIM stations. Elevation versus average annual precipitation curves was used to determine the elevation at which equal increments of precipitation would occur using various profiles across the drainages. Isohyetal lines (lines of equal precipitation) were drawn connecting known points of annual precipitation. These estimates show correlation with standard precipitation gages and provide the best available estimates of precipitation throughout Yellowstone's remote backcountry areas.