Flash floods and rough seas post danger during weekend of downpours: Forecast

The downpours will be brought by the strong monsoon trough lying across the North, Northeast and Central regions, and a strong southwest monsoon spanning the Andaman Sea and the Gulf of Thailand, the department said.

Flash flooding in foothills and overflowing waterways in lowland areas are a real danger, it warned. Motorists must exercise caution during thundershowers, the department advised.

Waves in the upper Andaman Sea and the upper Gulf will average two to three metres in height and swell to 3 metres during thundershowers, the department forecast. The lower Andaman Sea and Gulf, however, will see calmer seas with waves between one and two metres in height.

The department warned all ship pilots to be cautious and avoid thundershowers in the upper Andaman Sea and the upper Gulf.

The provinces (by region) that will be most affected by downpours are:

Saturday

North: Mae Hong Son, Chiang Mai, Lamphun, Lampang, Phrae, Uttaradit, Tak, Sukhothai, Kamphaeng Phet, Phitsanulok, Phichit, and Phetchabun

Northeast: Chaiyaphum, Nakhon Ratchasima, Buriram, and Surin

Central: Nakhon Sawan, Uthai Thani, Chai Nat, Lop Buri, Saraburi, Sing Buri, Ang Thong, Phra Nakhon Si Ayutthaya, Suphan Buri, Samut Songkhram, Samut Sakhon, Nakhon Pathom, and metropolitan Bangkok

East: Nakhon Nayok, Prachinburi, Sa Kaeo, Chachoengsao, Chonburi, Rayong, Chanthaburi, and Trat

South: Chumphon, Surat Thani, Nakhon Si Thammarat, Phatthalung, Ranong, Phang Nga, Phuket, Krabi, and Trang

Sunday

North: Mae Hong Son, Tak, Sukhothai, and Kamphaeng Phet

Northeast: Chaiyaphum and Nakhon Ratchasima

Central: Nakhon Sawan, Uthai Thani, Chai Nat, Lop Buri, Saraburi, Sing Buri, Ang Thong, Phra Nakhon Si Ayutthaya, Ratchaburi, and metropolitan Bangkok

East: Nakhon Nayok, Prachinburi, Sa Kaeo, Chachoengsao, Chonburi, Rayong, Chanthaburi, and Trat

South: Chumphon, Surat Thani, Nakhon Si Thammarat, Phatthalung, Ranong, Phang Nga, Phuket, Krabi, Trang, and Satun