Description: PRISM is an analytical model that uses point data and an underlying grid such as a digital elevation model (DEM) or a 30 yr climatological average (e.g. 1971- 2000 average) to generate gridded estimates of monthly and annual precipitation and temperature (as well as other climatic parameters). 800m spacing. In the Smokies, the average annual rainfall varies from approximately 55 inches in the valleys to over 85 inches on some peaks-more than anywhere else in the country except the Pacific Northwest, qualifying these upper elevation areas as temperate rain forests. During wet years, over eight feet of rain falls in the high country. The relative humidity in the park during the growing season is about twice that of the Rocky Mountain region. The broad range of elevations in the Great Smoky Mountains (<1000 to 6642 ft asl) contributes to the wide variety of climates therein. At the lower elevations (ca. 1000 ft) the climate is humid mesothermal with precipitation distributed throughout the year. At the uppermost elevations, which are among the highest attained in the Appalachian chain, the relatively cool, wet climate is perhumid microthermal. It supports evergreen coniferous forest vegetation rather than the deciduous forest vegetation typical of lower elevations. Total annual precipitation in the high-elevation coniferous forests rivals that of some of the wettest regions of the United States.
Copyright Text: The PRISM Group at Oregon State University