RELATIONSHIPS BETWEEN ATMOSPHERIC CIRCULATION AND SNOWPACK IN THE GUNNISON RIVER BASIN, COLORADO

In this study, winter mean 700 mbar height anomalies over the eastern North Pacific Ocean and the western USA are related to variability in snowpack accumulations measured on or about 1 April at 21 snowcourse s tations within and near the Gunnison River basin in Colorado. Results indicate that lower than normal snowpack accumulations are primarily a ssociated with positive 700 mbar height anomalies (anomalous anticyclo nic circulation) over the western USA. Moist air from the Pacific Ocea n is moved to the north of the western USA along the western margin of the anomalous anticyclonic circulation. In contrast, higher than norm al snowpack accumulations are associated with negative 700 mbar height anomalies (anomalous cyclonic circulation) over the western USA and o ver most of the eastern North Pacific Ocean. The anomalous cyclonic ci rculation over the western USA enhances the movement of moisture from the Pacific Ocean into the southern and central parts of the West. Res ults also indicate that variability in winter mean 700 mbar height ano malies can explain over 50% of the variability in snowpack accumulatio ns in the Gunnison River basin. The significant linear relationships b etween 700 mbar height anomalies and snowpack accumulations in the Gun nison River basin can be used in conjunction with general circulation model simulations of 700 mbar height anomalies for future climatic con ditions to estimate future snowpack accumulations in the Gunnison Rive r basin.