When will the heavy rainfall that triggered the disaster in Sumatra end?

Until when is the potential for heavy rain and extreme weather predicted to continue to hit the Sumatra region?

Based on the analysis of the Meteorology, Climatology, and Geophysics Agency (BMKG), the potential for rain with moderate to heavy intensity is expected to continue at least until early December. Specifically, heavy rain is predicted to still drench the regions of North Sumatra and West Sumatra on November 29-30 and December 1.

Meanwhile, for the Aceh region, the potential for moderate to heavy rain is predicted to occur on December 1. This extreme weather is not only happening locally but is also influenced by larger-scale regional atmospheric phenomena.

The main trigger for the high intensity of rainfall is the presence of a tropical cyclone. The Meteorology, Climatology, and Geophysics Agency (BMKG) has detected the activity of the Senyar tropical cyclone, which is affecting the weather patterns in the region.

The circulation center of Cyclone Senyar has been observed in the South China Sea, moving towards the northeast, which brings significant impacts in the form of heavy rain accompanied by strong winds in the Sumatra region and its surroundings. The presence of this low-pressure system prolongs the duration and increases the intensity of rainfall in the disaster area.

According to data from BMKG, Cyclone Senyar has triggered extreme rainfall in Aceh, North Sumatra, and West Sumatra with an intensity exceeding 300 millimeters (mm) per day. The highest rainfall was recorded in Kuala District, Bireun, with an intensity of 411 mm per day on November 25-26, 2025, as stated by the Head of the Aceh Climatology Station, Muhajir.

Regarding the efforts of weather modification operations (OMC) to reduce the intensity of rainfall, according to the Director of Meteorology at BMKG, Andri Ramdhani, the systems of tropical cyclone seeds or tropical cyclones cannot be effectively managed through OMC. This is due to the size and strength of their convective cells being very large.

"OMC can only be carried out after the cyclone has moved away and is focused on the evacuation stage and post-cyclone recovery to reduce the intensity of residual rain that still has the potential to cause puddles or flooding," he said.

Why did this rainfall trigger such massive flash floods and landslides?

Although high rainfall is the main trigger, experts assert that the scale of this massive damage is clear evidence of severe environmental degradation. Hydrology expert from Padjadjaran University, Chay Asdak, explained that the major floods carrying mud and timber from upstream cannot occur solely due to natural factors, but are exacerbated by land use changes.

Areas that should function as water catchment zones in the mountains and hills have been converted into plantation, agricultural, and mining areas. This change in function has caused the land to lose its ability to retain water flow.

Heri Andreas, an expert from ITB, added that flooding is closely related to how the land surface manages the incoming water. When natural vegetation cover such as forests is lost, the land's ability to absorb water (infiltration) decreases drastically.

This condition causes rainwater to flow quickly across the ground (runoff) into rivers, causing sudden surges in water levels and triggering flash floods. The high concentration of water on this steep, bare land then saturates the soil and makes it highly susceptible to landslides.

This situation is exacerbated by land use policies that do not adequately consider disaster management aspects. Land use permits for the forestry, agriculture, and mining sectors often proceed without strict oversight regarding their environmental impacts.

This disaster serves as a stern warning that national development programs must be implemented with the principle of caution to avoid encroaching on activities that could damage the ecosystem that supports the livelihoods of the community.

What is the current condition of the victims and how much has the number of people affected escalated?

The number of casualties continues to rise in line with the expanding reach of search and rescue (SAR) operations. As of Sunday (30/11/2025) afternoon, data from BNPB recorded that the number of fatalities has reached 442 individuals. In addition, 402 people are still reported missing. This surge in numbers occurred as SAR teams began to access areas that were previously completely isolated, allowing for more accurate victim data collection.

The humanitarian impact of this disaster is extensive, affecting three provinces simultaneously. In North Sumatra, 217 people have died and 209 are still missing; in Aceh, 96 lives have been lost and 75 are unaccounted for; and in West Sumatra, 129 people have died and 118 are missing. Reports indicate that tens of thousands of residents are still displaced in concerning conditions due to their homes being severely damaged or buried under landslide debris.

The biggest challenge currently is the fate of residents in areas that are still isolated. The Governor of Aceh, Muzakir Manaf, expressed his concern that residents in regions such as East Aceh and Gayo Lues may begin to experience hunger due to a total disruption of aid access for days. This disaster not only claims lives but also paralyzes the social fabric of the community as many residents lose family members and homes simultaneously.

What steps is the government prioritizing to break through isolation and restore access?

In response to this emergency situation, President Prabowo Subianto has instructed the mobilization of all national resources to focus on evacuation and the recovery of vital infrastructure.

The main priority at this time is to break the isolation of the affected areas, considering that many national roads and bridges have been completely severed, such as the Banda Aceh-Lhokseumawe route and the Sibolga-Tarutung route. The Ministry of Public Works has been deployed to carry out road normalization using heavy machinery on a massive scale.

Because land access is difficult, the government is employing an "air bridge" strategy for logistical distribution. The Indonesian National Armed Forces (TNI) has deployed Hercules transport aircraft, Cessna Caravans, and helicopters to distribute food, tents, and medical supplies directly to isolated areas. In Aceh, aid was even airdropped to points guarded by TNI soldiers for distribution to residents, reducing distribution time.

In addition to transportation, the restoration of communication has become an important focus due to the disruption of telecommunication networks in many disaster locations, which hampers data collection and coordination. As an emergency solution, BNPB and local governments have installed Starlink satellite internet devices at emergency response posts and evacuation points. This step is expected to expedite the flow of information regarding the needs of victims and the security status on the ground.