Fig. 1.

Schematic view of the proposed burned area forecast system. In order to forecast burned area (BA) in JJA of year N (dark grey shadow), we rely on the climate forecast issued on May of the same year (dashed line). Before May, we have the observed climate data, while from May on (light grey) we only have seasonal climate forecasts. Observations and forecasts can be merged to construct the SPI_t(M−m)−BA model, depending on the values of the parameters t (which can take a value of 3, 6 or 12 months) and M−m (which, in the illustrated example, can vary between March and August of year N, i.e. from the last month of the season being forecasted, back to the prior 6 months). As examples, we represent how climate observations and forecasts should be merged to compute SPI₁₂(7) (purple line); how SPI₃(8) is constructed from climate forecasts only (light blue line); and how SPI₆(4) (orange line) is computed only from observations