From the Stemboat Pilot & Today (Tom Ross):
[Art Judson, Steamboat weather observer and retired avalanche forecaster] explained how the density of the snowpack increases in the hours after a fresh snowfall. Density is an expression of how much water is contained in standing snow of a certain depth. “To get the density, you divide the snow depth into the water equivalent,” he said. Snow measuring sites maintained by the National Resources Conservation Service remotely sense the weight of the snowpack (revealing the water content) and its depth.
Snow depth had settled on Buffalo Pass on Wednesday to a depth of 37 inches and contained 9.5 inches of water. Simple division indicates a density of 0.256. “In Steamboat, the average density of new snow is 0.07. (actually 0.072),” Judson said. “One inch of snow with 0.07 water-equivalent equals a density of 0.07. To get the density, you divide the snow depth into the water equivalent. The main thing to remember is that snow is always densifying until it reaches the density of ice, which is 0.917.”