Weekly Weather Summary
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September 17, 2021 - September 23, 2021Max. Rainfall AmountMax. Temperature
Thailand
The monsoon trough lay across the northern and upper northeastern parts on the first day of the period then it moved southward to lie across the central, eastern and lower northeastern parts during the second half of the period. It lay toward the low pressure cell over Cambodia on Sep 20. which later moved to cover the lower central Thailand before moving into the Gulf of Martaban on Sep 22. In addition, the southwest monsoon prevailed over the Andaman Sea, southern part and the Gulf of Thailand throughout the period. These conditions caused plentiful rainfall over upper Thailand during the middle and the end of the period with flooding continued in many areas while southern part received rainfall mainly along the west coast. By the way, the active low pressure cell in the middle South China Sea intensified into a tropical depression and tropical storm “DIANMU (2115)” covering the coast of middle Vietnam on the last day of the period.    
Northern Part
Fairly widespread rain except for isolated to scattered rain on 18 and 19 Sep. Heavy rainfall in some areas throughout the period and very heavy rainfall in some places on 20 Sep. Flooding continued from the previous period at Tak, Phitsanulok, Kamphaeng Phet, Pichit, and Phetchabun provinces. Land slide occurred at Chiang Rai province on 20 Sep. 130.7 mm at Ramkhamhaeng National Park Sukhothai on 20 Sep.   
Northeastern Part
Isolated to scattered rain with heavy rainfall in some areas during early period then increasing in rainfall to fairly widespread rain with heavy rainfall in several areas and very heavy rainfall in some areas. Flooding continued from the previous period at Nakhon Ratchasima and Loei provinces. Flash flood occurred at Chaiyaphum province on 18 Sep. Gusty wind occurred at Ubon Ratchathani and Surin provinces on 19 Sep. 150.0 mm at Kanthararom Si Sa Ket on 19 Sep.   
Central Part
Isolated to scattered rain with heavy rainfall in some areas during early period then increasing in rainfall to fairly widespread rain and heavy to very heavy rainfall in some areas. Flooding occurred from the previous period at Phra Nakhon Si Ayutthaya province with gusty wind at Samut Sakhon and Ang Thong provinces on 19 Sep. 154.5 mm at Ban Pong Ratchaburi on 20 Sep.   
Eastern Part
Isolated to scattered rain during early period then increasing in rainfall to fairly widespread rain and heavy to very heavy rainfall in some areas. Flooding continued from the previous period in Prachin Buri province. Flash flood occurred in Chantaburi province on 18 Sep. and gusty wind at Nakhon Nayok province on 19 Sep. 162.2 mm at Tha Mai Chanthaburi on 21 Sep.   
Southern Part (East Coast)
Isolated to scattered rain except for fairly widespread rain on 19 and 21 Sep and heavy rainfall in some areas almost the period. 90.0 mm at Chaiya Surat Thani on 20 Sep.   
Southern Part (West Coast)
Fairly widespread rain with heavy rainfall in some areas mainly in the upper portion except for isolated rain on 17 and 23 Sep. Gusty wind occurred at Trang province on 19 Sep. 110.0 mm at Suk Samran Ranong on 20 Sep.   
Metropolitan
Isolated to scattered rain during early period then increasing in rainfall to fairly widespread rain with heavy rainfall in several areas and very heavy rainfall in some areas. 102.2 mm at Wat Dan School Khet Yannawa on 19 Sep. (150.5 mm at Thetsaban 1 School Samut Prakan on 20 Sep.)    
Weekly total Rainfall and Weekly mean minimum temperature Map
Issued Date September 24, 2021