For the thirty-seventh (37th) week of 2021, a total of 33 disasters (2 reports on drought, 19 floods, 5 landslides, 1 storm, and 6 wind-related) affected the region. Cambodia, Indonesia, the Philippines, Thailand, and Viet Nam have reportedly been affected. In Cambodia, prolonged heavy rainfall caused flooding in several cities in Banteay Meanchey as reported by the National Committee on Disaster Management (NCDM). Flooding caused by heavy rainfall and the overflowing rivers as well as droughts and severe winds have been reported by Indonesia’s Badan Nasional Penanggulangan Bencana (BNPB). Thailand’s Department of Disaster Prevention and Mitigation (DDPM) reported that the monsoon trough together with the western monsoon caused flooding and landslides in 14 provinces. Meanwhile in the Philippines, heavy rain due to the Inter-Tropical Convergence Zone was reported by the National Disaster Risk Reduction and Management Council (NDRRMC). Lastly, in Viet Nam, thunderstorms and whirlwinds affected 8 provinces as reported by the Viet Nam Disaster Management Agency (VNDMA).
According to DDPM, due to the influence of the monsoon trough across the north and the upper northeastern region together with the western monsoon over the Andaman Sea, the South, and the Gulf of Thailand, heavy to very heavy rainfall has reportedly occurred in 14 provinces since 16 Sep 2021. Flooding and landslides have reportedly affected 15.6K households (78.1K persons) across the following provinces: Chiang Mai, Lampang, Tak, Sukhothai, Phetchabun, Phichit, Kamphaeng, Phet, Chaiyaphum, Loei, Nakhon Ratchasima, Prachinburi, Chanhaburi, Ayutthaya, and Nakhon Si Thammarat. The situation has been resolved in 10 provinces (DDPM).
For the past week, data from the ASEAN Specialised Meteorological Centre (ASMC) showed noticeable high 7-day average rainfall in the Southwestern coast of Myanmar, in northern Viet Nam, Papua of Indonesia, and sparsely across the whole region. As of reporting, there are no tropical cyclone advisories in the region according to JTWC.
Three (3) significant earthquakes (M≥5.0) were recorded in the region by Indonesia’s Badan Meteorologi Klimatologi dan Geofisika (BMKG) and the Department of Meteorology and Hydrology (DMH). Volcanic activity was reported for Mount Semeru and Ibu (Alert level II) in Indonesia according to Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) and Taal Volcano (Alert Level 2), and Mount Kanlaon (Alert Level 1) according to the Philippine Institute of Volcanology and Seismology (PHIVOLCS).
According to the ASMC, for the coming week, wetter conditions are expected to continue over much of the Maritime Continent, parts of Mainland Southeast Asia, and the northern half of the Philippines with the highest probability over the southeastern Maritime Continent. For the regional assessment of extremes, there is a small increase in chance for a very heavy rainfall event in parts of northeastern Mainland Southeast Asia, southern tip of the Philippines, and central Maritime Continent and a moderate increase in chance in the eastern Maritime Continent. There is also a small increase in chance for extreme cold conditions in parts of Sulawesi, southern Borneo, and southern Philippines. A negative Indian Ocean Dipole (IOD) has developed over the Indian Ocean. At the seasonal timescale, negative IOD events tend to bring wetter conditions to the southern Maritime Continent.