DANA stands for Depresión Aislada en Niveles Altos (Cut-Off Low at Upper Levels). It is a pool of cold air at altitude (typically at the 500 hPa level, around 5,500 m) that detaches from the main polar jet stream circulation and becomes isolated over lower latitudes. The Spanish term has largely replaced the older informal name gota fría (cold drop), though the two concepts are not identical.
When a DANA sits over the western Mediterranean, it creates extreme instability: the cold air aloft lies above a sea surface that may exceed 25 °C in autumn, fuelling massive convective towers. The result can be torrential rainfall exceeding 200–400 mm in just a few hours, producing catastrophic flash floods. DANAs have been responsible for some of the deadliest flood events in Spanish history, including the Valencia floods of 1957, Alicante 1997, and more recently the severe events in 2019 and 2024.
DANAs are most frequent from September to November, when Mediterranean sea surface temperatures peak. On upper-air charts (500 hPa), they appear as closed low contours separated from the main westerly flow. Unlike frontal depressions, their movement is slow and erratic — they can remain quasi-stationary for days, prolonging heavy rainfall. Early detection via satellite imagery and numerical models is crucial for issuing timely warnings.