Wyoming Snowpack: Water in the Snow, Station by Station

Around April 18, taking the middle of the 84 Wyoming stations that publish a median peak date. That is a median of medians and no single basin hits it: across the state those station level peak dates run from March 27 to May 9, which is 43 days of spread inside one state, driven almost entirely by elevation and aspect. The typical melt out across the same stations is May 28. All of these are medians drawn from roughly four decades of record and none of them is a statement about this year.

89 active stations, of which 84 carry a 1991 to 2020 normal for a given calendar day and can therefore be given a percent of normal at all. They sit across 15 counties and 11 river basins, at elevations from 5,930 to 10,500 feet with a middle around 8,680. The highest is Med Bow at 10,500 feet. Every figure on this page states which of those two counts it was computed from.

In water rather than in depth, the middle Wyoming station typically peaks at about 15.1 inches of water, and the deepest, Grand Targhee at 9,260 feet, typically peaks at 48.8 inches. Nationally the range across the 12 covered states runs from 6.7 inches in Arizona to 32 in Washington. A station’s own median is far more useful than a state one, which is why the table on this page gives every station its own.

Wyoming is the roof. Water leaving it goes to the Columbia through the Snake, to the Colorado through the Green, and to the Mississippi through the Yellowstone and the Platte, so a Wyoming snow year is read by water managers in states that do not border it. The basins on this page are the six digit hydrologic units the federal station records carry, named from the United States Geological Survey boundary dataset, and the largest of them by station count is Big Horn.

The Natural Resources Conservation Service publishes seasonal runoff volume forecasts for 49 forecast points in Wyoming, and NOAA Missouri Basin River Forecast Center publishes river forecasts; both are linked from this page. What this page shows from that programme is the completed 2026 water year record, in the past tense, with the issue date printed on every number, so you can see how a forecast moved across a season. On Snake R ab Reservoir nr Alpine, the fifty percent forecast went from 3440 to 1830 thousand acre feet between the January 1 and April 1 issues, against a normal of 2140. For the current forecast, go to the agency.

No. Snowpack is one input to that question and this page publishes the input. The others are how dry the soil was before the snow fell, how fast the spring warms, whether rain falls on the snow, and how much dust settles on the surface and darkens it. Two identical Wyoming snowpacks in two different years can deliver very different amounts of water for those reasons, which is precisely why the agency issues its runoff forecast monthly and revises it, as the 2026 arcs further down this page show rather than computing it once from a snow number. For Wyoming drought conditions themselves, the United States Drought Monitor is the published record and it is a different measurement from this one.

Two reasons, and the page distinguishes them. 5 of the 89 Wyoming stations have no 1991 to 2020 median at all, almost always because they were installed too recently to have thirty years behind them, and a station with no normal cannot be a percentage of one. Separately, a station reporting exactly zero water against a normal of an inch or more is held out, because in this network that pattern is usually a failed sensor. Measured against the agency’s own quality flags for March 15, 2026, that rule held out 0 Wyoming stations and the agency had independently flagged 0 of them as not valid.

On elevation, Wyoming’s middle station sits at 8,680 feet against 10,275 in Colorado and 1,345 in Alaska, and elevation is not a proxy for depth: the deepest packs in the country sit on some of the lowest stations, because a maritime climate delivers far more water per storm. On timing, Wyoming peaks around April 18 against March 2 in Arizona and April 20 in Montana. The hub page puts all 12 side by side.