Climatology for Wildfire Management

Abstract

Forest and wildfire managers in the western United States are very familiar with weather information and forecasts provided by various public and private sources . Even very sophisticated users of these products, however, may be less familiar with climate information and forecasts and their applications . Partly this is because the scientific community has made rapid progress in climate, and particularly climate forecasting, as a field of applied study in recent decades . Integrating these new research findings into management systems is a difficult and time-consuming process . Sophisticated users of weather information may also be less comfortable using climate information because, conceptually, the two are so different: weather is something we all experience every day, while climate is an abstraction . As an abstraction, however, climate provides powerful tools for understanding recent developments in forest wildfire in the western United States . Climate and wildfire research, and the practical experience of many forest managers, show that summer drought is a very important driver of interannual variability in forest wildfire (Balling et al . 1992, Swetnam and Betancourt 1998, Kipfmueller and Swetnam 2000, Veblen et al . 2000, Donnegan et al . 2001, Heyerdahl, Brubaker and Agee 2002, Westerling et al . 2003b) . In turn, the duration and severity of summer drought in western forests is highly sensitive to variability in spring and summer temperature at higher latitudes and elevations and its effect on snow (Westerling et al . 2006) . Trends in temperature and the timing of the spring snowmelt explain much of the dramatic increase in large forest wildfire frequency in the West in recent decades (Westerling et al . 2006), and these trends in wildfire are probably driving most of a similar increase in fire suppression costs . Recent research has demonstrated the feasibility of producing seasonal forecasts of temperature, drought, and wildfire activity in the western United States (Alfaro et al . 2005a, Alfaro et al . 2005b, Westerling et al . 2002, Westerling et al . 2003a) . Based on surveys of fire managers in California and the Southwest (conducted by Corringham, Westerling and Morehouse, in press), these forecasts may be useful for planning wildfire suppression budgets, allocating resources within the annual cycle of fire seasons in different parts of the United States, and prioritizing fuels management projects . Obstacles remain however, from