From climatology to hazard: environmental regimes and tornado wind-speed exceedance in peninsular Spain and the Balearic Islands

Abstract. Tornadoes and waterspouts are infrequent but locally damaging hazards in the Iberian–Mediterranean region, where uneven reporting and intensity uncertainty hamper their assessment. We compiled an updated 1992–2025 catalogue for peninsular Spain and the Balearic Islands by merging the national meteorological agency's tornado records with a pan-European severe-weather database, harmonising event times to UTC and removing duplicates, which yielded 1185 events: 567 tornadoes and 618 waterspouts. The record is temporally heterogeneous, with a late-summer to autumn maximum and a marked diurnal split between morning waterspouts and late-afternoon tornadoes; its rising counts appear to track reporting practices rather than any climatic trend. Using 54 pre-event atmospheric-reanalysis (ERA5) parameters, we tested a six-region geographical framework that proved only partially separable, so a simpler structure emerged: Ward clustering of 50 km hexagonal cells resolves three broad regimes — shear-dominated in the west and southwest, thermodynamically charged in the central-southeast, and weakly forced in the north and east. Adapting a footprint-based occurrence-to-exceedance model, we derived the first regime-dependent wind-speed exceedance estimates for the region. Notably, the least active regime holds four of the five Enhanced Fujita Scale 3 (EF3) tornadoes and dominates exceedance at 180 and 220 km h⁻¹, so where tornadoes are most frequent is not where the strongest winds are most likely. These results provide a first catalogue-based baseline for regime-dependent tornado and waterspout hazard assessment in peninsular Spain and the Balearic Islands.