7649 20251114152453.0 CTALK-2025-0101 Senthamizh Pavai, Valliappan The May 2024 Geomagnetic Storm - Challenges in Forecasting 2025 2025-09-05 The May 2024 geomagnetic storm (NOAA Kp=9) was among the most intense of Solar Cycle 25, driven by multiple Earth-directed CMEs from SIDC Sunspot Group 74 and 75 (NOAA AR 3663 and 3664). This event featured ten X-class flares, complex ICME interactions, and extreme Bz fluctuations (-48 nT), leading to widespread disruptions, including GICs in power grids, HF communication blackouts, severe GNSS scintillation, and satellite anomalies. For space weather forecasters, this event posed significant real-time analysis and prediction challenges. Rapid assessment of CME propagation, speed, and impact potential relied on tools such as STEREOCat and SWPCCat for initiation parameters, and EUHFORIA and the Drag-Based Model for heliospheric propagation. However, CME-CME interactions made impact predictions highly complex, as successive CMEs altered shock arrival times, enhanced solar wind speeds, and prolonged magnetospheric disturbances, increasing uncertainty in impact assessments. This presentation will explore the operational challenges faced by space weather forecasters, the differences and limitations of current prediction models, and the need for improved data assimilation and real-time modeling to better anticipate the dynamics of complex geomagnetic storms. 3ESA_SWESNET/ 3ESA_SWESNET/ 3ESA_SWESNET NO Space weather, CME, CME-CME interactions, May 2024 event Shukhobodskaia, Daria de Patoul, Judith Rodriguez, Luciano Carella, Francesco Magdalenic1, Jasmina IAGA / IASPEI Joint Scientific Meeting 2025, Coimbra, Portugal pavai.valliappan@ksb-orb.be Contributed CTALKCONT