Thailand braces for heavier rain as monsoon trough returns

Thailand is facing wetter conditions today as the monsoon trough returns across the upper part of the country, bringing heavier rain to several regions and raising the risk of flash floods in vulnerable areas.

The Thai Meteorological Department (TMD) said rain would increase across Thailand over the next 24 hours, with heavy rain expected in some areas of the North, Northeast, Central region, Bangkok and surrounding provinces, and the East.

The department said the weather pattern was being driven by a monsoon trough lying across Myanmar, the upper North of Thailand and upper Laos, extending into a low-pressure cell over upper Vietnam. A moderate southwest monsoon is also continuing to cover the Andaman Sea, Thailand and the Gulf of Thailand.

People in affected areas have been advised to prepare for heavy rain and accumulated rainfall, which could trigger flash floods and forest runoff, especially in low-lying communities and areas close to waterways.

In Bangkok and nearby provinces, thunderstorms are expected across 60% of the area, with heavy rain in some places. Temperatures are expected to range from 25–27 degrees Celsius in the morning to 34–36C during the day, with southwesterly winds of 10–20 kilometres per hour.

The North is also forecast to see thunderstorms across 60% of the region, with heavy rain in Mae Hong Son, Chiang Mai, Chiang Rai, Nan and Tak. Temperatures are expected to range from 23–26C to highs of 32–36C.

In the Northeast, thunderstorms are expected across 40% of the region, with heavy rain in some areas including Loei, Nong Khai, Bueng Kan, Sakon Nakhon, Nakhon Phanom, Nakhon Ratchasima and Buri Ram. Temperatures are forecast at 23–26C in the morning and 33–37C in the afternoon.

The Central region is expected to see thunderstorms across 40% of the area, with heavy rain in Nakhon Sawan, Uthai Thani, Chai Nat, Lop Buri, Saraburi, Phra Nakhon Si Ayutthaya, Kanchanaburi, Ratchaburi and Nakhon Pathom. Temperatures are expected to reach 34–37C.

In the East, thunderstorms are forecast across 60% of the region, with heavy rain in Nakhon Nayok, Prachin Buri, Rayong, Chanthaburi and Trat. Seas are expected to have waves of about one metre, rising above two metres during thunderstorms.

The South will see less widespread rain than the upper regions. On the east coast, thunderstorms are expected across 40% of the area, mainly in Surat Thani, Nakhon Si Thammarat, Phatthalung, Songkhla, Pattani, Yala and Narathiwat. On the west coast, thunderstorms are forecast across 30% of the area, mainly in Krabi, Trang and Satun.

Marine conditions remain a concern during storms. The upper Andaman Sea is expected to see waves of one to two metres, while the lower Andaman Sea and the Gulf of Thailand will have waves of about one metre. In areas with thunderstorms, waves may rise above two metres.

TMD has advised sailors in the Andaman Sea and the Gulf of Thailand to proceed with caution and avoid sailing through thunderstorm areas.

The department’s seven-day outlook indicates that rain will increase from June 17–19, with heavy rain in some areas, before easing in many parts of the country from June 20–22. However, heavy rain may still occur in some areas of the North and the East during that later period.