The TORRO scale (Tornado and Storm Research Organisation scale) is a tornado intensity classification developed by Dr. Terence Meaden in 1972 in the UK. It extends from T0 (~60 km/h — light) to T11 (~480+ km/h — super), providing finer gradation than the Enhanced Fujita scale — each T number roughly corresponds to half an EF number. T0–T1 ≈ EF0, T2–T3 ≈ EF1, and so on up to T10–T11 ≈ EF5.
The TORRO scale was designed with European conditions in mind, where tornadoes are generally weaker than in the US Great Plains but still cause significant damage. The scale uses damage descriptors appropriate to European building types (brick and masonry rather than timber-frame) and vegetation. It is widely used in the UK, Ireland, France, Germany, and other European countries, alongside the EF scale. The European Severe Storms Laboratory (ESSL) catalogues European tornadoes using both scales.
TORRO also maintains an extended scale for hailstones — the TORRO Hailstorm Intensity Scale (H0 to H10) — rating hail from pea-sized (H0, 5–9 mm) to grapefruit-sized (H10, >100 mm). This complements the tornado scale by covering another key severe weather hazard. In Spain, where approximately 10–15 tornadoes are reported annually (most rated T0–T4), the TORRO scale's fine resolution is useful for characterising the relatively weak but locally damaging events that affect regions like the Ebro valley, the Mediterranean coast, and Andalusia.