Natural Hazards and Earth System Sciences

Abstract. The Iberian Peninsula presents the highest num-ber of wildfires in Europe. In the NW of Spain in particular, wildfires are the natural risk with the greatest economic im-pact in this region. Wildfires caused by lightning are closely related to the triggering of convective phenomena. The pre-diction of thunderstorms is a very complex task because these weather events have a local character and are highly de-pendent on mesoscale atmospheric conditions. The devel-opment of convective storms is directly linked to the exis-tence of a synoptic environment favoring convection. The aim of this study is to classify the atmospheric patterns that provide favorable environments for the occurrence of wild-fires caused by lightning in the region of Castile and Leon, Spain. The database used for the study contains 376 wild-fire days from the period 1987–2006. NCEP data reanaly-sis has been used. The atmospheric fields used to charac-terise each day were: geopotential heights and temperatures at 500 hPa and 850 hPa, relative humidity and the horizontal wind at 850 hPa. A Principal Component Analysis in T-mode followed by a Cluster Analysis resulted in a classification of wildfire days into five clusters. The characteristics of these clusters were analysed and described, focusing particularly on the study of those wildfire days in which more than one wildfire was detected. In these cases the main feature ob-served was the intensification of the disturbance typical of the cluster to which the wildfire belongs.