Publications

Variability and trends in mountain snowpack in western North America

Citation

Mote, P.W., Hamlet, A.F., Lettenmaier, D.P. 2004. Variability and trends in mountain snowpack in western North America. In F. Wagner (ed.), Proceedings of the American Association for the Advancement of Science Pacific Division 85th Annual Meeting, Ashland, Oregon: American Association for the Advancement of Science Pacific Division.


Abstract

Manual and automated measurements of spring snowwater equivalent (SWE) in the mountainous West are examined in combination with a simulation of the region’s snow by a hydrology model. Declines in spring SWE since the mid-20th century were widespread, and were largest in the relatively mild mountain areas of northern California and the Pacific Northwest, even though in many cases winter precipitation has increased. In most mountain ranges, relative declines grow from minimal at ridgetop to substantial at snowline. Analysis of the separate influences of temperature and precipitation trends underscores the varying sensitivity to temperature across the region and even within mountain ranges, and provides an additional means of estimating future temperature-driven losses in the region’s snow resources.