A tourist board with 53 people on board (48 Vietnamese tourists and five crew members) capsized in Hạ Long Bay following a sudden thunderstorm on July 19 afternoon. — VNA/VNS Photo

HÀ NỘI — A powerful line of thunderstorms tore through northern Vietnam and the Gulf of Tonkin on Saturday afternoon, unleashing torrential rain, lightning, and fierce winds that culminated in a tragic capsizing of a tourist boat with 53 people on board in Hạ Long Bay, officials said.

The National Centre for Hydro-Meteorological Forecasting attributed the extreme weather to a convergence zone sweeping through the region, which, combined with three days of scorching temperatures, created unstable atmospheric conditions ripe for severe storms.

Meteorologists classified the event as a Mesoscale Convective System (MCS), a sprawling complex of thunderstorms that can span hundreds of km and persist for up to 24 hours. The system brought heavy downpours, lightning, strong gusts, and scattered whirlwinds to the region.

The provincial hydro-meteorological station had been tracking the developing weather system, issuing warnings based on real-time radar data. Specifically, upon detecting developing convective clouds, the station issued two warnings at 11:45am and 1:30pmon July 19. The second bulletin warned of showers and thunderstorms affecting areas including Hạ Long ward, a popular tourist destination.

According to an urgent report from the provincial Steering Committee for Natural Disaster Prevention and Search and Rescue, a tourist boat, QN7105, carrying 48 passengers and five crew members, capsized around 3 pm on July 19 after being battered by a sudden whirlwind and thunderstorm. The incident occurred between Hòn Gà Chọi (Fighting Cock Islet) and Bài Thơ Mountain, roughly three nautical miles from shore.

A total of 47 people have been recovered, with ten survivors and 37 confirmed dead, including four victims whose identities are still being verified. The search continues amid challenging conditions.

The National Centre for Hydro-Meteorological Forecasting anticipated turbulent weather, with a marine bulletin issued at 4:30 am on July 19 forecasting scattered showers and thunderstorms across the Gulf of Tonkin by nightfall, along with the potential for whirlwinds and gusty winds. An extended-range forecast issued on July 18 afternoon had also warned of light rain during the day and thunderstorms at night along the Bãi Chay coastal area, including Hạ Long Bay, with the possibility of rough seas.

Looking ahead, the centre predicted continued showers and thunderstorms across the Gulf of Tonkin and northern and central of the East Sea (internationally known as the South China Sea), including the Hoàng Sa (Paracel) archipelago, starting on July 20. The northern part of the northern East Sea is expected to face particularly severe conditions, with heavy rainfall and strong winds forecast. — VNA/VNS