CHEYENNE, Wyoming — Unseasonably warm weather has melted the winter snowpack up to six weeks early in parts of Wyoming, according to the Natural Resources Conservation Service.
As of April 1, the state's mountain snowpack was 70 to 75 percent of average and its water equivalent was 67 percent of median.
The snowpack is slightly below normal in the Upper Green River Basin of southwest Wyoming. But in the Belle Fourche and Cheyenne river basins in northeast Wyoming, the snow has virtually melted out.
"They are pretty near a month earlier than it's ever been before," Lee Hackleman, NRCS water supply specialist, said.
The early melt is being compounded by below normal precipitation.
March saw little snowfall, with the statewide precipitation 45 to 50 percent of average, according to the National Oceanic and Atmospheric Administration.
Hackleman said normally Wyoming sees its most snowfall in March and April.
"Basically in March we didn't get nothing; all we got was hot temperatures," he said. "And the hot temperatures were worse at the lower elevations. So all of the lowest sites, like the Black Hills sites are all pretty low, so they just all melted out."
However, the highest elevations in the mountain still retained a decent amount of snow, he said.
The numbers continue to point to a below-normal spring runoff from the mountain snowpack in nearly all the major river basins in Wyoming.
The Upper North Platte, the Wind, the Little Snake and the Bear river basins all are expected to have well below normal runoff volumes. Near normal streamflow volumes are expected across the Yellowstone and Clarks Fork drainage as well as the South Fork of the Shoshone River Basin.
Hackleman said the good news is that Wyoming's reservoirs, which are the main source of water for crop irrigation and municipal water, are 120 percent of normal because of last year's good runoff and precipitation.
"They got a lot of fill on the reservoirs last year," he said.