General weather patterns:
From 14 to 20 April 2020, there was no rainfall in the LMB. The weather outlook bulletins (3 months weather forecast) and maps issued by the Thailand Meteorology Department (TMD) were used to verify the weather condition in the LMB. They stated that from April to May 2020, sweltering and dry weather with little humidity will occurs with very hot weather on some days, As a result, summer thunderstorms occur influencing the rain amount of this month to increasemore than that of the past month.
However, sometime coldly high-pressure air masses from China will meet hot air masses already prevailing over LMB, resulting in abnormal rain. They also stated that summer thunderstorms will often occur at short durations over the LMB in April and early May. Figure 1 presented the weather map on 15 and 19 April 2020