A stated limitation of the survey is that, because the tornado occurred over the water, officials could not evaluate damage to trees and structures – which is typically necessary to determine whether a tornado actually touched down and its strength.
The violent windstorm that tipped over a Chinese ferry boat carrying 458 people Monday evening originated from a towering group of thunderstorms that may have spawned a tornado.
The thunderstorms soared 40 to 50 thousand feet high in the atmosphere and were fueled by a very warm, humid stream of air from the China Sea.
The China Meteorological Administration says the storm reached level 12 on the Beaufort wind scale, which equates to wind of hurricane force, over 74 mph.
The storm not only unleashed devastating wind gusts but also unloaded over 2.5 inches (64.9 mm) of rain between 9 and 10 p.m. according to China Daily.
The storm complex developed during the rainy season on the Yangtze river, when large thunderstorms are common and tornadoes can occur. But conditions on Monday were particularly favorable for damaging storms.
Simulations from the GFS model portray hotter than normal temperatures, lower than normal pressures and abundant low level moisture in the region – ingredients which heightened the risk for severe weather.
Above normal temperatures provided heat necessary to destabilize the atmosphere
Lower than normal pressures promoted rising air motions for storm development
A deep plume of moisture originating from the China Sea helped energized the storms
The turbulent weather pattern has persisted since the accident and is hampering rescue efforts and the search for survivors.