Heavy to very heavy rain is forecast over seven southern provinces during May 25-29 as a result of Tropical Cyclone "Yaas" now prevailing over the Upper Bengal Bay, according to the 5am weather forecast of the Thai Meteorological Department on Tuesday.
As of 1am, Tropical Cyclone "Yaas" was moving in a north-northwesterly direction with maximum sustained winds of about 95 kilometres per hour.
It is expected to make a landfall over Upper India on Wednesday or Thursday. The cyclone will intensify the southwestern monsoon privailing over the Andaman Sea, South Thailand and the Gulf of Thailand.
Heavy to very heavy rain is forecast for South Thailand in Phetchaburi, Prachuap Khiri Khan, Chumphon, Ranong, Phangnga, Phuket and Krabi provinces on Wednesday and Thursday (May 26-27).
Strong waves are likely in the Andaman Sea and the Gulf of Thailand: 2-4 metres high in the Andaman Sea and above 4 metres in areas with thundershowers, about 2m high in the Upper Gulf of Thailand and 1-2m in the Lower Gulf of Thailand.
All vessels along the Andaman Sea coastline are advised to stay ashore while those in the Gulf of Thailand should proceed with caution.