November 26, 2025 | 10:31 pm
TEMPO.CO, Jakarta - Storms rarely make landfall in Aceh. But the 95B cyclone seedlings intensified into Tropical Cyclone Senyar, wreaking havoc in the Malaysian Peninsula with major floods, and extreme rainfall in the northern parts of Sumatra.
Growing unusually in the narrow strip of the Malacca Strait since November 21, this storm made landfall in Langsa, Aceh—near the border with North Sumatra—on Wednesday morning, November 26, 2025.
Erma Yulihastin, a climate and atmosphere researcher at the National Research and Innovation Agency (BRIN), considered this a highly unusual event.
The Meteorology, Climatology, and Geophysics Agency (BMKG) reported widespread heavy downpours overnight into Wednesday. Adding to the increased rainfall that has lashed the region over the past week, nine out of 23 regencies/cities in Aceh are suffering from floods and landslides.
The city of Langsa in Aceh sits 4.5 degrees north of the equator, making Cyclone Senyar the second tropical storm to defy the norm. In December 2001, Typhoon Vamei formed even closer to the equator, at 1.3 degrees N, or 150 kilometers away from it in the South China Sea near Singapore.
Meaning, Senyar is notably the second storm to make southernmost landfall in the Northern Hemisphere, just behind Vamei.
Why Can Storms Approach the Equator?
Storms, whether typhoons, cyclones, or hurricanes, form when stormy rains churn the atmosphere over warm ocean waters (sea surface temperature anomalies). The Earth's rotation causes the disturbance to then move in a spinning motion, aided by what is called the Coriolis force. This force becomes zero at the equatorial region, so it is believed that any storm seedling will not be able to develop in this belt.
For this reason, researchers were surprised when Typhoon Vamei swept the northern part of Singapore more than two decades ago. The typhoon unleashed rainfall that created flood disasters in the southern part of the Malaysian Peninsula.
In their paper published in Geophysical Research Letters, a peer-reviewed journal, on February 1, 2003, meteorologist C.P. Chang from the Naval Postgraduate School in Monterey, California, and his colleagues mentioned several factors that built Vamei almost into a perfect storm. He pointed to, among other things, the Borneo vortex that persisted for days in the warm South China Sea waters.
At the same time, a strong cold monsoon wind rapidly surged from the northeast between Borneo and Indochina. This wind enveloped the vortex and made it spin without the assistance of the Earth's rotation effect. The wind and the storm lasted long enough, and the South China Sea was also wide enough, to elevate Vamei to typhoon strength.
Chang, as quoted from science.org, at that time calculated that such a rare situation might not occur again in the next 100-400 years.
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