Heavy rains and rough seas expected as monsoon strengthens, tropical storm Wihpa develops

The Thai Meteorological Department on Friday issued a warning as a low-pressure cell continues to cover upper Myanmar and northern Vietnam, while the moderate southwest monsoon prevails over the Andaman Sea, Thailand, and the Gulf of Thailand.

Isolated heavy rainfall is expected in the North, Central, and East regions, with the potential for flash floods and water overflows, especially in areas near waterways, foothills, and lowlands. Residents in these areas are advised to remain vigilant for sudden downpours and the possibility of flooding.

Waves in the upper Andaman Sea are expected to reach 2 metres, while waves in the lower Andaman Sea and the upper Gulf will be around 1-2 metres, with waves exceeding 2 metres in areas with thunderstorms. All ships are urged to proceed with caution and avoid areas affected by thundershowers.

Additionally, the tropical depression over the eastern Philippines has intensified into Tropical Storm Wihpa, which is forecast to pass through the upper Philippines and move into the upper South China Sea between July 19-22. This development is expected to strengthen the southwest monsoon over Thailand, leading to more rainfall and the possibility of isolated heavy to very heavy rain throughout the country.

Stronger winds will drive waves in the Andaman Sea and upper Gulf of Thailand to 2–3 metres, with waves rising above 3 metres during thundershowers. People are urged to stay updated on weather warnings and take necessary precautions.

The weather forecast for the next 24 hours is as follows:

North: Scattered thundershowers and isolated heavy rain in Mae Hong Son, Chiang Mai, Chiang Rai, Lamphun, Lampang, Tak and Kamphaeng Phet; minimum temperature 23-25 degrees Celsius, maximum 30-35°C.

Northeast: Scattered thundershowers mostly in Loei, Nong Khai, Bueng Kan, Roi Et, Yasothon, Amnat Charoen, Nakhon Ratchasima, Surin, Sisaket and Ubon Ratchathani; minimum 23-26°C, maximum 33-36°C.

Central: Scattered thundershowers and isolated heavy rain in Kanchanaburi, Ratchaburi, Saraburi, Nakhon Pathom, Samut Songkhram and Samut Sakhon; minimum 23-25°C, maximum 34-36°C.

East: Scattered thundershowers and isolated heavy rain in Nakhon Nayok, Chachoengsao, Chanthaburi and Trat; minimum 24-27°C, maximum 32-35°C; waves about a metre high and above 2 metres high in thundershowers.

South (east coast): Isolated thundershowers mostly in Phetchaburi, Prachuap Khiri Khan, Chumphon and Surat Thani; minimum 23-26°C, maximum 34-36°C; waves about a metre high and above 2 metres high in thundershowers.

South (west coast): Scattered thundershowers mostly in Ranong, Phang Nga and Phuket; minimum 24-26°C, maximum 31-34°C; waves 1-2 metres high and above 2 metres high in thundershowers.

Bangkok metropolitan area: Fairly widespread thundershowers and isolated heavy rain; minimum 24-26°C, maximum 33-35°C.