Why Typhoon Bualoi is moving twice as fast as normal storms
 

Typhoon Bualoi is currently moving across the East Sea at nearly double the speed typical of storms in the region, creating a rare and potentially dangerous scenario for Vietnam. Experts attribute this unusual rapidity to a combination of atmospheric and oceanic conditions that could amplify the storm’s impact.

After striking the central Philippines on Friday at speeds of 35–40 kph—almost twice the usual 15–20 kph—Bualoi entered the East Sea, internationally known as the South China Sea, three hours earlier than anticipated. It is now advancing west-northwest toward Vietnam at 30–35 kph. Historically, only a few typhoons, such as Dot in 1985, Linda in 1997, and Doksuri in 2017, have traveled this fast.

According to Truong Ba Kien, Deputy Director at Vietnam’s Center for Meteorological and Climate Research, the storm is propelled by an exceptionally strong subtropical high, which functions like a conveyor belt, pushing the typhoon forward. Additionally, a developing monsoon trough has connected with Bualoi, helping maintain both its rapid pace and a stable trajectory.

The surrounding environment is unusually conducive to Bualoi’s acceleration. The atmosphere is relatively clear, free from disruptive wind shear or turbulence, while the sea surface is warm and energetically rich. These conditions allow the storm to remain compact, potent, and fast-moving as it approaches Vietnam. Nguyen Minh Truong, Deputy Dean of Meteorology, Hydrology, and Oceanography at Hanoi University of Science, identifies three main drivers of the storm’s speed: a strong and uninterrupted steering flow in the mid-troposphere, asymmetric atmospheric processes within the storm’s core, and extensive high sea surface temperatures spanning from the western Pacific to the South China Sea.

Experts also note that the Coriolis effect, which deflects moving air and water to the right in the northern hemisphere, is reinforcing the storm’s west-northwest path. Meanwhile, the expanding subtropical high toward Vietnam is nudging Bualoi northward, increasing the likelihood of landfall in north-central provinces such as Thanh Hoa or Nghe An.

What makes Bualoi particularly dangerous is the combination of its speed and potential intensification. Forecast models indicate a greater than 50% probability that the typhoon will strengthen by two to three levels within 24 hours, potentially reaching level 13 with wind speeds of up to 149 kph or higher while still over the sea. Its rapid movement could drive strong winds further inland than usual, and if the landfall coincides with high tide at night, the risk of a severe storm surge would be extreme, Kien warns.

Heavy rainfall is also expected to affect northern and north-central Vietnam, increasing the risk of flash floods, landslides in mountainous regions, and significant urban and lowland flooding. Even after Bualoi moves into Laos, its circulation may continue to bring dangerous rainfall to western Thanh Hoa, Nghe An, and areas along the Vietnam–Laos border, particularly near hydropower dams and reservoirs.

Authorities have called for all vessels to return to shore immediately and have banned any sea trips. Preparations are underway to evacuate residents from coastal, low-lying, and landslide-prone areas, while infrastructures such as dikes, homes, schools, and hospitals are being reinforced. People are urged to secure their properties, stockpile food and clean water, and rely solely on official forecasts and warnings to ensure safety.