Maneva, Yana; ; Millas, Dimitrios; ; Shukhobodskaia, Daria; ; Senthamizh, Pavai Valliappan; ; de Patoul, Judith

Talk presented at ESWW25, Umea, Sweden on 2025-10-28

Abstract: Extreme geomagnetic storms have become more often over the recent years as we have reached and passed beyond the maximum levels of activity for the current solar cycle 25. Extreme storms are typically caused by arrivals of fast coronal mass ejections either linked to active regions and related flaring activity or driven by underlying filament or prominence eruptions. Real-time forecasting of extreme events presents great challenges for the on duty space weather forecasters. Some are related to delays in the available space weather data and the limited time for events analysis. A major challenge arises from the complexity of having multiple independent or inter-related space weather events one after the other as was the case for the May 2024 event. This work considers the complexity of the May 2024 event for space weather forecasting, including multiple daily Earth-directed CMEs which lifted off the solar surface particularly on May 08 and May 09. Analysing the intricate nature of this event we perform comparison between expected CME arrivals and related impacts based on isolated modelling of the individual CMEs, including the largest CME throughout the period, with forecasted arrival and impact predictions based on heliospheric modelling including all relevant CMEs. We include cross-model arrival time validation for selected CMEs throughout the event and compare them with the observed in situ solar wind data. Finally we conclude on the lessons learned from the analysis of this complex event and suggest possible ways forwards for future forecasting improvements.

Keyword(s): CME modelling and arrival predictions, ; May 2024 event, ; space weather forecasting
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