AN OBJECTIVE FORECASTING-MODEL FOR THE DAILY OUTBREAK OF FOREST-FIRESBASED ON METEOROLOGICAL CONSIDERATIONS

Daily fire risk (DFR) is a forecasting index defined on the basis of t wo meteorological parameters. Such parameters are associated with the local atmospheric column: dry stability e in 850-700-hPa layer and sat uration deficit D in 850-hPa level. In an earlier study, and from data collected over 10 years, a categorization of four type days based on DFR was established. In this way, from evaluation of e and D at 0000 U TC for each particular day, the associated type day was deduced. Conse quently, it is possible to know whether that day had either very high, high, low, or very low fire activity. With this technique it is not p ossible to forecast a numerical value for the number of fires, however . In this paper a model for estimating the outbreak of fires is presen ted. On the basis of an autoregressive process, AR(2), it is possible to obtain the predicted number of fires (PNF) during a day d as PNF(d) = F[TD(d), RNF(d - 1), RNF(d - 2)], where TD(d) is the type day accor ding to the categorization established on the basis of e and D (deduce d from rawinsoundings at 0000 UTC) and RNF(d - 1) and RNF(d - 2) are t he numbers of fires registered over the area during two previous days. In contrast to other papers in the literature, all fires are consider ed. No limitations are placed on the burned area or other measures of fire activity. Several statistical computations confirm the validity o f this model.