China renewed an orange wave alert on Thursday as Typhoon Dolphin, the 13th named storm of the year, moves through the East China Sea.

The alert was issued by the National Marine Environmental Forecasting Center at 8 am. The country has a four-tier warning system for waves, with red representing the highest, followed by orange, yellow and blue.

From Thursday morning to Friday morning, the eastern East China Sea is expected to see waves of 6 to 10 meters, triggering an orange alert for the offshore waters, according to the center.

A blue alert was also issued for the nearshore waters off Zhejiang province, where waves of 2 to 3 meters are forecast during the period.

The center urged vessels operating in affected areas to exercise caution and called on coastal authorities to take preventive measures.