General weather patterns
The weather outlook bulletins for the 3 months (Jul-Aug-Sep) and weather maps issued by the Thailand Meteorology Department (TMD) were used to verify the weather condition in the LMB. From 21 to 20 July 2020, there were no heavy rainfalls over the Lower Mekong Basin (LMB). The TMD expected of low pressures and air mass cells will develop around the Mekong Region at the end of July and continue to August and September which can bring above-average rainfall in the Mekong region. They also predicted of scattered to fairly widespread thundershowers with isolated heavy rain from August to September 2020. It also that will be some tropical cyclones move to dissipate nearby the LMB, which will have abundance of rainfall. Figure 1 presented the weather map on 26 July 2020.
According to the Asian Specialized Meteorological Centre (ASMC), the increased shower rainfall over the Mekong sub-region, above-normal rainfall and hotspot activities will be happened in August and September 2020. In the southern ASEAN region, rainfall over most parts of the equatorial region is predicted to be above normal in August-September 2020.
Consequently, from August to September 2020, there will increasing chance of moderate rainfall to above average rainfall for most parts of the Asian countries especially in the Mekong region. Figure 2 showed the rainfall outlook from 27 July to 09 August 2020 in Southeast Asia, which showed the above-normal rainfall for the Mekong region.
Source: Mekong River Commission