BEIJING - The China National Marine Environmental Forecasting Center (NMEFC) on Friday afternoon raised the yellow warning for very high seas and waves generated by typhoon Haiyan to orange.

Haiyan, the 30th and strongest typhoon to hit China this year, is now influencing the eastern part of the South China Sea, with 3 meter waves ?near Dongsha island, the center said.

From Friday night to Saturday daytime, 6 to 9 meter waves will appear, with 3 to 4 meter waves further north.

As waves may reach 9 meters, the NMEFC ?asked ships to return to port, and told coastal areas to take precautionary measures in advance.

The Bohai and Yellow Seas will also be ?very rough on Saturday with 3 to 4.5 meter waves, while 2 to 3 meter waves will hit Liaoning, Hebei, Tianjin and the Shandong Peninsula.

The NMEFC also issued a blue alert for storm surge, estimating that from Saturday noon to night, 50 to 130 centimeters of storm surge will appear in Bohai Sea, and Laizhou Bay in southern Bohai will be hit by 60 to 160 centimeters of storm surge.

Orange is the third tier in China's four-tier color-coded weather warning system, with blue the first and least serious.