Snow Quality--the Issue of Water Content and Temperature

Early on I realized I needed to qualify some of the snowfall quantity data by reviewing snow quality, since this has a major effect on both skiability of big dumps as well as subsequent surface conditions. The Westwide Network data sheets showed water precipitation as well as snow from 1979 to 1995. I selected 10 western areas plus Mt. Washington, the highest mountain in the Northeast, and calculated average water content and air temperatures for 50-90 months of data. Then I determined how many of those months had 15-20 percent water (heavy, wet snow) and over 20 percent water (a strong indicator of rain). The results in the following tables shouldn't surprise anybody. Rain or snow over 15 percent water are basically nonexistent at any of the Rocky Mountain sites. Mammoth's altitude protects it from winter rain but not from Sierra cement. Mt. Washington receives more rain than any of the western sites despite much lower average temperatures.

The following table dramatically illustrates the incidence of rain between East and West. The Mt. Mansfield (Stowe, Vermont) figures are based upon daily records from 1982 to 1998 at 3,950 feet, near the top of the ski area. Southern California figures are based upon snow reports from 1978 to 1998 at an average elevation of 7,500 feet. In the East precipitation is as high in fall and spring as in the winter and is much more likely to be rain. In the West fall and spring are drier than winter but at most ski areas the precipitation will still be snow.--T.C.