It said the storm is moving slowly northwest with sustained winds of about 90 kilometres per hour. It added that the monsoon trough will lie across Myanmar and the upper North of Thailand before shifting into the low-pressure cell over Laos. A strong southwest monsoon, meanwhile, will prevail over the Andaman Sea, Thailand and the Gulf.
Rains with gusty winds have been forecast for some parts, while isolated heavy rains are expected in the North, Northeast, East and the southern coast.
People have been warned to beware of rivers breaking banks and flash floods.
The following areas will be affected today and tomorrow:
July 1
July 2
Fierce winds will whip up waves of 2-3 metres high and more than 3 metres in areas with thundershowers in the upper Andaman.
The upper Gulf will see waves of around 2 metres high and more than 2 metres in areas experiencing thundershowers.
Ships are warned to proceed with caution and keep away from areas with thundershowers, while small boats in the upper Andaman Sea should keep ashore until Wednesday.