BEIJING, July 17 (Xinhua) -- The National Meteorological Center (NMC) activated a level IV emergency response on Tuesday for the Typhoon Son-Tinh approaching China's southern provinces Hainan and Guangdong.

Son-Tinh, the ninth typhoon this year, is expected to make landfall in the coastal regions of Hainan and Guangdong on Wednesday morning, the center warned.

According to the blue alert issued by the center, the typhoon was centered on the northeastern South China Sea 710 kilometers away from Wenchang, Hainan as of 10 a.m. Tuesday.

It is forecast to move westward at a speed of 40-45 km/h with mounting intensity. It will make landfall on Wednesday morning in the coastal regions from Lingshui, Hainan, to Leizhou, Guangdong.

In China's four-tier severe weather warning system, red is the most severe alert, followed by orange, yellow and blue.