The Meteorological Department warns that Phetchabun, Phitsanulok, Mae Hong Son, and Tak are high-risk areas for heavy rainfall until 22 Aug 2021 GMT+7. El Niño is expected to cause repeated drought in the Northeast from Oct to Dec, while Bangkok shows no flood signals this year.
The accumulated rainfall in the upper Nan River basin has caused increased water levels in the Nan and Yom Rivers, resulting in flooding in some areas.
Thairath Online's special task force interviewed Mr. Somkuan Tonjan, Director of the Forecasting Division and Deputy Spokesperson of the Meteorological Department, regarding heavy rain prospects in the North. Currently, flooding persists in Nan, Chiang Rai, Chiang Mai, and Phayao provinces with light rain throughout the day, but not as intense as on 18 Aug. Rainfall remains light to moderate, requiring monitoring over the next 2-3 days.
It is forecasted that after 22 Aug, rainfall will decrease and conditions will improve, but caution is still needed regarding accumulated water and ongoing runoff. Some areas along the monsoon trough in the North may experience heavy rain again at the end of August, so the situation must be closely watched.
Assessments indicate that within the next two days, the most concerning areas to monitor are the lower North regions such as Phetchabun, Phitsanulok, parts of Mae Hong Son, and Mae Ramat District in western Tak Province bordering Myanmar, especially along the mountainous monsoon trough in the North.
The Nan River remains critical, but this wave arrived quickly. Water is gradually receding through Mueang District, and if no additional rain falls, the situation may return to normal after tomorrow. It is expected that no further significant rainfall will occur, as water levels are already decreasing.
In Sukhothai Province, some flooding has occurred partly because there are no flood-retention dams. Without upstream runoff from the North, severe flooding is unlikely, with only localized flooding when water flows down from the northern basin. Provided no additional rain falls, and considering Sukhothai had low water reserves earlier this year, it can still absorb the current water levels, so there is little cause for concern.
In Bangkok and its metropolitan area, rain continues to alternate between heavy and light in the evenings and nights, but there is nothing alarming or requiring special monitoring. Some days may see faster movement of rain clusters or stronger monsoons, but overall rainfall will gradually lessen.
Mr. Somkuan forecasted that this year's El Niño will peak in strength between October and December, reaching 3.1 on the scale, representing a very strong El Niño phase. After this peak, intensity will gradually weaken from January to March, swinging back to moderate levels, then easing further to a weak El Niño before the next rainy season begins.
El Niño’s peak severity coincides with Thailand’s dry season, when rainfall is naturally low. Therefore, the key factor to mitigate crisis risks will be rainfall replenishing reservoirs and dams during August and September before the dry season ends.
The Northeast is the most drought-prone region of concern, especially Nakhon Ratchasima, Buriram, and Surin provinces, where rainfall is below average and water storage sources are insufficient. This poses a high risk of severe water shortages for both agricultural use and daily consumption.
The Central region, though affected, is expected to manage through the crisis due to remaining water reserves in large dams such as Bhumibol and Sirikit, which can release water into the Chao Phraya basin to supply public water needs during August and September.
