Tropical storm Wipha weakened after making landfall in northern Vietnam on Tuesday, with authorities on alert due to heavy rains that could cause flooding and mudslides, as the Philippines struggled with monsoon downpours that began last week.

Wipha was a tropical storm in the Gulf of Tonkin Monday evening Eastern time, the Joint Typhoon Warning Center said in its latest advisory. The tropical storm had sustained wind speeds of 52 miles per hour.

A tropical storm is intensifying and is expected to reach typhoon strength before hitting southern China's coast on Sunday.