BEIJING, July 19 -- China's national observatory on Saturday issued a yellow alert for Typhoon Wipha as the sixth typhoon of the year is expected to bring strong winds and heavy rain to the southern coastal regions of the country.

The typhoon, observed at 19.9 degrees north latitude and 120.2 degrees east longitude at 5 a.m. Saturday, is moving northwestward at a speed of 15-20 km per hour, according to the National Meteorological Center.

It is anticipated to make landfall along the coastal areas from Shenzhen City in south China's Guangdong Province to Wenchang City in Hainan Province during the afternoon or evening on Sunday, the meteorological center said.

China has a four-tier, color-coded weather warning system for typhoons, with red representing the most severe warning, followed by orange, yellow, and blue.