Chinese weather officials sent to site of capsized ship

Chinese meteorological officials have been sent to the site where a passenger ship capsized on the Yangtze River to study what weather events may have caused the accident.

Zhang Zuqiang, a director from the China Meteorological Administration, told a news conference on Tuesday that officials were certain that “severe weather” had affected the area of the central Hubei province where the boat turned over on Monday night, the China Daily reported.

Zhang said it was not yet known if a sudden tornado had caused the accident. He said that meteorological officials have been sent to the area to study the conditions.

While the precise circumstances remain unknown, satellite imagery from the region does reveal a large cloud circulation, and weather stations in the vicinity of the river were reporting 24-hour rainfall totals of between 50mm and 80mm.

Wettest season

The idea of a major storm hitting the Yangtze is certainly plausible, given the region is now entering the rainiest part of the year along the Yangtze, Asia’s longest river.

The bad weather originates from the Meiyu-Baiu rainband. This develops as a consequence of the interaction of two vastly different air masses: the warm, moist air of the northward-moving East Asian monsoon; and the southward movement of drier air of the subtropical high pressure in the western Pacific.

Where these two air masses meet, rainfall can be both torrential and persistent. The rainband usually reaches the Yangtze from the south at the start of June. As rain falls into the Yangtze and waters pour down steep-sided valleys into the tributaries, flow rates become enormous.

In 1931 it is thought that up to four million people lost their lives in severe flooding that hit eastern China. As recently as 1998, 3,700 people died as a result of floods.

In recent years, the construction of the mighty Three Gorges Dam was, in part, intended to control the flow of the waters of the Yangtze.

At the time of Monday night’s incident, during the hours of darkness, the flow of the river was such that in the time between capsize and coming to rest, the vessel reportedly travelled more than 3km.

Fortunately, it is likely that the area in which the vessel lies will experience quieter weather conditions as the rescue efforts continue in the coming hours and days.