Heavy rain is forecast to continue in provinces in all regions, including Bangkok, from Saturday into Wednesday, with flash floods and overflows expected in high-risk areas. Bangkok Post

Heavy rain forecast nationwide

A huge volume of rainwater draining off from Muang district in Nakhon Ratchasima flows into tambon Chan-ad in Non Sung district through the Lam Chiang Krai river on Friday. (Photo: Prasit Tangprasert)

Heavy rain is forecast to continue in provinces in all regions, including Bangkok, from Saturday into Wednesday, with flash floods and overflows expected in high-risk areas.

The Meteorological Department on Friday said another high-pressure system from China will extend into upper Laos and upper Vietnam between Sept 17 and 21, This will cause a monsoon trough to move down and lie across the North, Central and Northeast of Thailand. The southwest monsoon prevailing over the Andaman Sea and the Gulf of Thailand will strengthen.

These conditions are expected to bring heavy to heavy rain with sometimes gusty winds to hit the North, Northeast and Central Plains, including Bangkok and its vicinity, the East and the South.

Residents of those area should make appropriate preparations. Accumulated rainwater may cause flash flooding and watercourses to overflow, particularly near foothills and in low-lying areas.

On Sept 17, affected areas are likely to be seven provinces in the North (Chiang Rai, Phayao, Nan, Tak, Kamphaeng Phet, Phichit and Phetchabun), 12 provinces in the Northeast (Nong Khai, Bueng Kan, Udon Thani, Sakon Nakhon, Nakhon Phanom, Mukdahan, Roi Et, Yasothon, Amnat Charoen, Surin, Si Sa Ket and Ubon Ratchathani), and four provinces in the East (Chon Buri, Rayong, Chanthaburi and Trat).

Between Sept 18 and 19, likely affected areas are 12 provinces in the North (Mae Hong Son, Chiang Mai, Lamphun, Lampang, Phrae, Uttaradit, Sukhothai, Phitsanulok, Phichit, Phetchabun, Kamphaeng Phet and Tak), 15 provinces in the Northeast (Loei, Nong Khai, Bueng Kan, Udon Thani, Yasothon, Chaiyaphum, Khon Kaen, Maha Sarakham, Roi Et, Amnat Charoen, Nakhon Ratchasima, Buri Ram, Surin, Si Sa Ket and Udon Thani), five provinces in the Central Pains (Nakhon Sawan, Uthai Thani, Kanchanaburi, Lop Buri and Saraburi), Bangkok and its vicinity, all provinces in the East (Chachoengsao, Nakhon Nayok, Prachin Buri, Sa Kaeo, Chon Buri, Rayong, Chanthaburi and Trat) and five provinces in the South (Phetchaburi, Prachuap Khiri Khan, Surat Thani, Ranong and Phangnga).

Between Sept 20 and 21, affected areas are 15 provinces in the North (Mae Hong Son, Chiang Mai, Chiang Rai, Lamphun, Lampang, Phayao, Nan, Phrae, Uttaradit, Sukhothai, Phitsanulok, Phichit, Phetchabun, Kamphaeng Phet and Tak), 20 provinces in the Northeast (Loei, Nong Bua Lamphu, Nong Khai, Bueng Kan, Udon Thani, Sakon Nakhon, Nakhon Phanom, Mukdahan, Yasothon, Kalasin, Chaiyaphum, Khon Kaen, Maha Sarakham, Roi Et, Amnat Charoen, Nakhon Ratchasima, Buri Ram, Surin, Si Sa Ket and Ubon Ratchathani), nine provinces in the Central Plains (Nakhon Sawan, Uthai Thani, Suphan Buri, Sing Buri, Ang Thong, Lop Buri, Saraburi, Ayutthaya and Samut Sakhon), Bangkok and its vicinity, and all provinces in the East.

Waves up to 1-2 metres high are forecast for the upper Andaman Sea and the upper Gulf of Thailand, and more than 2 metres high during thundershowers.  All boats should proceed with caution.