Southeastern China, Vietnam and Laos will face flooding downpours from a tropical system through Friday night.
The deluge will raise the risk for dangerous flash flooding and mudslides.
AccuWeather meteorologists are closely monitoring a tropical system set to track from the South China Sea to the Gulf of Tonkin late this week.
Proximity to land has been the main inhibitor to the system's ability to strengthen.
If the system pushes far enough away from land, it could organize over the warm water and be designated as a tropical depression or storm by the Joint Typhoon Warning Center.
The system has already been classified as a tropical depression by the Japan Meteorological Agency and Hong Kong Observatory.
Regardless of its strength, the system threatens to spread flooding rain from China's southeastern Guangdong province to northern Laos through Friday night.
Downpours totaling 50-100 mm (2-4 inches) of rain may trigger localized flash flooding in Hong Kong and Macau into Thursday.
The heaviest rain, totaling 100-200 mm (4-8 inches) with locally higher amounts, will target China's Leizhou Peninsula and Hainan Island, northern Vietnam and northern Laos.
Significant flash flooding and mudslides are serious concerns.
Residents should prepare for possible road closures and heed any evacuation orders.
The risk of rough surf in the Gulf of Tonkin and locally damaging winds in northern Vietnam will increase if the system strengthens into a tropical storm.
The potential for further strengthening will end after the system moves inland on Friday.
However, the danger for enhanced tropical downpours and localized flash flooding will persist through this weekend over central Myanmar and toward the mountains of northeastern India.