Heavy rain compounds northern flood risk with Bangkok storms

Heavy to very heavy rain is forecast across northern and upper northeastern Thailand on Friday (August 21), threatening to worsen flooding in affected communities, while thunderstorms are expected across 70% of Bangkok and its surrounding provinces.

The Thai Meteorological Department (TMD) forecast thunderstorms across 80% of both the North and Northeast, with very heavy rain in several provinces. Parts of the Central and Eastern regions, including Bangkok and its vicinity, could also experience heavy rain.

The conditions are being caused by a monsoon trough extending across the North and upper Northeast towards an active low-pressure cell over Hainan, China. A rather strong southwest monsoon is also prevailing over the Andaman Sea, Thailand and the Gulf of Thailand.

People in affected areas have been advised to remain alert for heavy and accumulated rainfall that could cause flash floods, run-off and river overflows, particularly in foothill communities near waterways and in low-lying areas.

Strong waves forecast in Andaman Sea and upper Gulf

Waves in the upper Andaman Sea and upper Gulf of Thailand are forecast to reach two to three metres, rising above three metres during thunderstorms.

In the lower Andaman Sea, waves will be about two metres high and exceed two metres in stormy areas.

Mariners should proceed with caution and avoid sailing in areas affected by thunderstorms. Small boats in the upper Andaman Sea and upper Gulf should remain ashore.

Weather forecast from 6am Friday to 6am Saturday

Bangkok and surrounding provinces

• Thunderstorms are forecast across 70% of the area.
• Temperatures will range from lows of 25–27°C to highs of 31–34°C, with southwesterly winds of 10–25 kilometres per hour.

North

• Thunderstorms are forecast across 80% of the region.
• Heavy rain is expected in Mae Hong Son, Chiang Mai, Chiang Rai, Lamphun, Phayao, Nan and Phrae.
• Very heavy rain is forecast in parts of Lampang, Kamphaeng Phet, Uttaradit, Sukhothai, Tak, Phitsanulok, Phichit and Phetchabun.
• Temperatures will range from 23–26°C to 27–32°C, with southwesterly winds of 10–20km/h.

Northeast

• Thunderstorms are forecast across 80% of the region.
• Heavy rain is expected in Bueng Kan, Sakon Nakhon, Nakhon Phanom, Chaiyaphum and Khon Kaen.
• Very heavy rain is forecast in parts of Loei, Nong Khai, Nong Bua Lamphu and Udon Thani.
• Temperatures will range from 22–25°C to 26–30°C, with southwesterly winds of 10–20km/h.

Central region

• Thunderstorms are forecast across 70% of the region, with heavy rain in parts of Nakhon Sawan, Uthai Thani, Kanchanaburi and Ratchaburi.
• Temperatures will range from 23–25°C to 28–33°C, with southwesterly winds of 10–25km/h.

East

• Thunderstorms are forecast across 70% of the region, with heavy rain in parts of Nakhon Nayok, Prachin Buri, Chanthaburi and Trat.
• Temperatures will range from 23–28°C to 29–33°C, with southwesterly winds of 20–40km/h.
• Waves will reach two to three metres and exceed three metres during thunderstorms.

South, east coast

• Thunderstorms are forecast across 40% of the region, mainly in Phetchaburi, Prachuap Khiri Khan and Chumphon.
• Temperatures will range from 23–26°C to 29–36°C.
• From Surat Thani northwards, southwesterly winds will reach 20–35km/h. Waves will be one to two metres high, rising above two metres offshore and during thunderstorms.
• From Nakhon Si Thammarat southwards, southwesterly winds will reach 15–35km/h. Waves will be about one metre high, rising to one to two metres offshore and above two metres during thunderstorms.

South, west coast

• Thunderstorms are forecast across 40% of the region, mainly in Ranong and Phang Nga.
• Temperatures will range from 23–27°C to 28–34°C.
• From Phuket northwards, southwesterly winds will reach 20–40km/h. Waves will be two to three metres high and exceed three metres during thunderstorms.
• From Krabi southwards, southwesterly winds will reach 20–35km/h. Waves will be about two metres high and exceed two metres during thunderstorms.