TMD issues Thailand warning for heavy rain, hail and flash floods

The Thai Meteorological Department (TMD) has warned of heavy to very heavy rain, gusty winds and hail in parts of Thailand through October 7, with flash floods and forest run-off possible in vulnerable areas.

In Warning No. 9, issued at 5pm on Monday (October 5), the department forecast unstable weather over upper Thailand from October 5–7, bringing thunderstorms, gusty winds, hail and locally heavy to very heavy rain.

The North, the Central region, including Bangkok and its vicinity, the East and the upper South are expected to face the main effects on October 5–6, while rainfall in the Northeast is forecast to ease.

By October 7, the areas most affected by the unstable conditions are expected to shift towards the western parts of the North and Central regions.

Flash-flood risk in vulnerable areas

The conditions are being driven by a high-pressure system or cool air mass from China extending over the North and upper Northeast at the end of the rainy season. The southwest monsoon continues to prevail over the Andaman Sea, the South and the Gulf of Thailand.

The TMD urged people to watch for thunderstorms, gusty winds and heavy or accumulated rainfall, which could trigger flash floods and forest run-off.

People living on foothills, near waterways and in low-lying areas should be particularly cautious, as flooding could develop where drainage is limited. The public was also advised to avoid open areas, large trees and insecure billboards during thunderstorms and strong winds.

Waves to strengthen in Andaman Sea and Gulf

Winds and waves in the Andaman Sea and Gulf of Thailand are expected to strengthen, with waves exceeding two metres in thunderstorm areas.

Mariners should check weather and sea conditions before travelling, navigate with caution and avoid areas affected by thunderstorms.

The department also forecast an increase in rainfall from October 9–13 across the East, the Central region, including Bangkok and its vicinity, and the South, with heavy to very heavy rain possible in some areas.

Provinces expected to be affected from October 5–7

October 5

Provinces expected to be affected by very heavy rain

• North: Kamphaeng Phet and Sukhothai

Provinces expected to be affected by heavy rain

• North: Chiang Mai, Chiang Rai, Lamphun, Lampang, Phayao, Nan, Phrae, Uttaradit, Tak, Phitsanulok, Phichit and Phetchabun
• Northeast: Loei, Nong Bua Lamphu, Khon Kaen, Chaiyaphum, Nakhon Ratchasima, Buri Ram and Surin
• Central: Nakhon Sawan, Uthai Thani, Chai Nat, Sing Buri, Ang Thong, Phra Nakhon Si Ayutthaya, Lop Buri, Saraburi, Suphan Buri, Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Sakhon and Samut Songkhram, as well as Bangkok and its vicinity
• East: Nakhon Nayok, Prachin Buri, Sa Kaeo, Chachoengsao, Chon Buri and Rayong
• South: Phetchaburi, Prachuap Khiri Khan, Chumphon, Surat Thani, Nakhon Si Thammarat, Phuket, Krabi, Trang and Satun

October 6

Provinces expected to be affected by heavy rain

• North: Mae Hong Son, Chiang Mai, Chiang Rai, Lamphun, Lampang, Phayao, Nan, Phrae, Sukhothai, Tak, Kamphaeng Phet, Phitsanulok and Phichit
• Central: Nakhon Sawan, Uthai Thani, Chai Nat, Kanchanaburi, Ratchaburi, Suphan Buri, Nakhon Pathom, Samut Sakhon and Samut Songkhram, as well as Bangkok and its vicinity
• East: Chon Buri, Rayong, Chanthaburi and Trat
• South: Phetchaburi, Prachuap Khiri Khan, Chumphon, Surat Thani, Nakhon Si Thammarat, Phatthalung, Songkhla, Ranong, Phang Nga, Krabi and Trang

October 7

Provinces expected to be affected by heavy rain

• North: Mae Hong Son, Chiang Mai and Tak
• Central: Kanchanaburi and Ratchaburi
• East: Chon Buri, Rayong, Chanthaburi and Trat
• South: Phetchaburi, Prachuap Khiri Khan, Chumphon, Surat Thani, Phatthalung, Songkhla, Pattani, Yala, Narathiwat, Ranong and Trang

Bangkok faces 80% chance of thunderstorms

For the 24-hour period from 6pm on October 5 to 6pm the following day, the regional forecast is:

• North: Thunderstorms over 70% of the area, with heavy rain, gusty winds and hail in some places. Very heavy rain is forecast in Kamphaeng Phet and Sukhothai. Minimum temperatures of 21–25C and maximum temperatures of 33–37C.
   
• Northeast: Thunderstorms over 60% of the area, with heavy rain and gusty winds in some places, particularly in Loei, Nong Bua Lamphu, Khon Kaen, Chaiyaphum, Nakhon Ratchasima, Buri Ram and Surin. Minimum temperatures of 21–23C and maximum temperatures of 33–35C.
   
• Central: Thunderstorms over 70% of the area, with heavy rain, gusty winds and hail in some places. Minimum temperatures of 24–27C and maximum temperatures of 34–36C.
   
• East: Thunderstorms over 70% of the area, with heavy rain and gusty winds in some places. Minimum temperatures of 24–26C and maximum temperatures of 32–35C.
   
• South, east coast: Thunderstorms over 60% of the area, with heavy rain in some places. Minimum temperatures of 22–24C and maximum temperatures of 33–35C.
   
• South, west coast: Thunderstorms over 40% of the area, with heavy rain in some places. Minimum temperatures of 23–25C and maximum temperatures of 32–34C.
   
• Bangkok and vicinity: Thunderstorms over 80% of the area, with heavy rain and gusty winds in some places. Minimum temperatures of 25–26C and maximum temperatures of 33–35C.