Tropical depression Lionrock was moving from upper Laos to the upper Northeast of Thailand on Monday morning, bringing heavy to very heavy rain, the Meteorological Department said in its 11am forecast.
At 7am the tropical depression had weakened to a low-pressure cell in upper Laos. By 10am it was moving onto the upper Northeast of Thailand, bringing heavy to very heavy rain.
People in flood-prone areas of the upper and lower Northeast should be aware of accumulated rainwater that could overflow and cause a flash flood.
The weather office said a monsoon trough is lying across the lower North and Central regions, and the strong southwest monsoon prevails across the Andaman Sea, the South region and the Gulf of Thailand.
Heavy to very heavy rain is likely in some areas in the North, Central and East and on the western coast of the South.
Wind-raised waves in the Andaman Sea and the upper Gulf of Thailand were 2-3 metres high and about 2m high in the lower Gulf, and more than 3m high in areas with thundershowers.
All vessels were advised to proceed with caution. Small boats should stay ashore.