In east-facing canyons in the coastal mountains of California, the daytime thermal up-canyon winds are frequently replaced, usually in early afternoon, by a moderately strong down-canyon wind. The same type of wind has also been noted in the western foothills of the Sierra Nevada. This shift in the wind to down canyon is important in wildland fire control and has been a factor in some fire-fighting fatalities. Results of a fire-climate survey conducted in northwestern San Diego County to study these winds show that, in the summer and early fall of 1959, winds switched to down canyon in the afternoon on about one-quarter of the days. From the surface records and a few double-theodolite and airplane observations, a diagrammatic model of this phenomenon has been constructed. The stability of the lower atmosphere along the coast was closely related to the occurrence of down-canyon winds in the area studied. The possibility of making short-range predictions exists by using this relationship along with other considerations.
Introducing GIS-based simulation tools to support rapid response in wildland fire fighting
