Two heavy-rain scenarios forecast for central Vietnam as Tropical Storm No. 6 could form over the South China Sea

Central Vietnam could face two possible periods of heavy rain as cold air, a tropical convergence zone and a potential sixth storm over the South China Sea combine, according to the National Center for Hydro-Meteorological Forecasting.

On September 8, scattered showers and thunderstorms were expected from Quang Tri to Da Nang, in eastern parts of Quang Ngai through Dak Lak, and across southern Vietnam. Rainfall was forecast at 10 to 30 millimeters, with some areas receiving more than 50 millimeters. The Central Highlands could see 15 to 30 millimeters of rain during the afternoon and night, with isolated totals above 70 millimeters.

Forecasters warned that thunderstorms could bring tornadoes, lightning, hail and strong wind gusts. These conditions could damage crops, uproot trees and harm homes, transport facilities and other infrastructure. Intense local rainfall could also trigger flash floods on small rivers and streams, landslides on steep slopes and flooding in low-lying areas.

From September 9, a tropical convergence zone is expected to develop over the South China Sea, with its axis passing through the central-central region of Vietnam. Forecasters gave a 70-80% chance that a tropical depression would form over the central South China Sea around September 12-13. They put the chance of the system strengthening into a storm at 30-40%. If it forms, it would become the sixth storm over the South China Sea in 2026.

A weak cold-air outbreak could affect northern Vietnam from September 9 to 11, with a 70-80% chance of occurring. Under the first scenario, assessed at 60-70%, heavy rain would begin in central Vietnam on September 10 and continue through September 16, with the heaviest area from Ha Tinh to Gia Lai. Under the second scenario, assessed at 30-40%, rain would start around September 14 and last until about September 17, focusing from Nghe An to Hue.