Twisters difficult to predict, experts say

Experts say that the tornado that hit Kaiyuan city, Liaoning province, on Wednesday, was hard to forecast with current detection equipment.

The tornado was formed by fierce convective currents brought by a cold vortex that originated in Northeast China and a cyclone that originated in Mongolia.

At 4:42 pm on Wednesday, Liaoning provincial early warning center issued a yellow warning signal of thunder and lightning in Kaiyuan city. It also forecast that in the next two to three hours, strong convective weather such as short-term heavy rainfall, strong winds and hail would occur.

Later at 5:25 pm, the meteorological observatory in Tieling city, which oversees Kaiyuan, issued an orange warning signal for hail in Kaiyuan that was expected to last one to three hours.

These warning signals were released to the public through mobile phone messages, Weibo and WeChat official accounts and the meteorological emergency broadcast system.

Zhang Bingchuan, chief forecaster of the provincial meteorological observatory, said that in extremely unstable thunderstorm weather, the atmosphere is more likely to be strongly convective.

He said that tornadoes belong to this kind of small-scale, strong and sudden convective disaster weather, which occurs and dissipates in a short time.

The areas where tornadoes occur are so small that current detection instruments cannot accurately observe them.

Lu Zhongyan, head of the Liaoning meteorological observatory, said that tornadoes tend to occur in wide and open spaces. However, the investigation is still ongoing about exactly where and how it happened on Wednesday.

According to the China Meteorological Administration, China doesn't have a warning system exclusively for tornadoes. Tornado warnings are sorted as strong convection weather.

It is also a technical difficulty for other countries to detect tornadoes accurately. In 2010, the error rate of tornado warnings was 70 percent in the United States.

The administration said that from 1991 to 2014, China had 43 tornadoes a year on average with Jiangsu and Guangdong provinces experiencing most, 5.5 and 4.8 times on average a year.

Spring and summer are tornado seasons. The number of tornadoes from April to August accounts for 92 percent of the entire year on average.