Large-scale circulation-conditioned attribution of the historic 2024 Spanish extreme precipitation

On 29 October 2024, Turís, Spain, recorded an unprecedented 24-hour precipitation total of 771 mm, triggering one of the deadliest floods in Europe since 1900. Although recent attribution studies demonstrated that anthropogenic warming may have contributed to the event, the extent to which atmospheric circulation variability shaped its exceptional magnitude remains unclear. Using multi-source high-resolution precipitation observations, this study uncovers the dynamical and thermodynamical mechanisms driving the event. The exceptional precipitation is initiated by an anomalously deep upper-level cut-off low over southern Spain, accompanied by a southeasterly jet that enhanced the transport of warm, moisture-laden air from the Mediterranean. Circulation analogue analysis reveals that pre-trough dynamics explain ~31% (interquartile range: 7–44%) of the maximum daily precipitation across eastern Spain during October–November 2024. Large-ensemble attribution using the HadGEM3-A-N216 model further confirms the crucial role of internal dynamics, which account for approximately one-third of the total anomaly, while the remaining signal is dominated by the combined contribution of anthropogenic forcing and internal thermodynamic processes. These results highlight the important role of atmospheric circulation in shaping Mediterranean precipitation extremes, emphasizing the need for explicitly accounting for circulation variability in event attribution and future regional flood risk assessment.