Some experts worry a drying climate means U.S. Drought Monitor tool isn’t effective out West

With more persistent and severe droughts in the Western United States, experts who rely on a national tool that measures a region’s aridness to determine drought policy say there needs to be changes to accurately reflect the trend of a drying climate.

The U.S. Drought Monitor, developed by the U.S. Department of Agriculture and used for nearly 25 years, measures dryness through multiple factors, including precipitation, ground and reservoir water levels, soil moisture and snowpack.