(a) Basic data are currently collected at numerous sites in the western states area. Data sites generally include a snow course where both snow depth and water equivalent of snow are measured. However, special sites may measure only snow depth or water equivalent. Many of these sites also provide related drometeorological data, such as precipitation, temperature, humidity, solar tradiation, and wind.

(b) Water supply forecasts in the western states area are generally made monthly from January through June. Forecasts may be made more frequently for an established need when data are available to NRCS.