Extreme Rainfall and Hydrometeorological Impacts of Tropical Cyclone Senyar in Aceh, Indonesia: A Regional Spatial Synthesis Ahmad Farhan1*, Muhammad Syukri1, Susanna1, Teuku Muhammad Hary Ramadhan1, Muhammad Syukri2, Saumi Syahreza2, Taufan Hidayat3, Muhammad Okta Ridha Maulidian4, Muhajir5, and Muhammad Rizal5
1 Department of Physics Education, Universitas Syiah Kuala, Banda Aceh 23111, Indonesia
2 Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Syiah Kuala, Banda Aceh 23111, Indonesia
3 Department of Agrotechnology, Faculty of Agriculture, Universitas Syiah Kuala, Banda Aceh 23111, Indonesia
4 Department of Geography Education, Universitas Syiah Kuala, Banda Aceh 23111, Indonesia
5 Aceh Climatology Station, Indonesian Meteorological, Climatological and Geophysical Agency (BMKG), Aceh Besar, Indonesia
Corresponding author: farhan[at]usk.ac.id
Abstract
Tropical Cyclone Senyar, which developed in the low latitude region of the Malacca Strait on November 26-27, 2025, triggered a rare and high impact extreme precipitation event in Aceh Province. Daily rainfall values severely exceeded the BMKG extreme threshold of more than 150 mm per day. This low latitude phenomenon was driven by multi scale atmospheric disturbances, including the intensification of the Asian Monsoon, a weak La Nina anomaly, and equatorial waves that enhanced tropical depression 95B into Cyclone Senyar. This study assesses the resulting widespread flooding, landslides, and vital infrastructure damage using an integrated spatial synthesis approach. Observational data indicate a heterogeneous distribution of extreme rainfall, with the ARG Meureudu and Kuala stations recording the highest daily accumulations at 376.6 mm and 411 mm, respectively. The intense rainfall triggered severe fluvial flooding across downstream alluvial plains and widespread slope failures in the upstream Bukit Barisan zone due to a sharp reduction in residual soil shear strength. Significant structural damage was documented on downstream transportation infrastructure due to lateral erosion and impacts from massive driftwood. Furthermore, severe scouring caused the collapse of regional power transmission towers, resulting in prolonged regional blackouts. This study emphasizes the urgency of strengthening structural mitigation frameworks and multi risk early warning systems in equatorial regions to address the increasing trend of low latitude tropical cyclones driven by global climate change.
