 The China Meteorological Administration released a press release after the storm and gave four reasons for the extensive damage . First , the storm decelerated after landfall and maintained its identity for 120 hours while moving south of due west . Secondly , the storm was asymmetric and rainfall concentrated in the southern semicircle . Also , the storm interacted with the active monsoon over the South China Sea , and the Hong Kong Observatory reported a 1 @-@ hour rainfall total of 115 @.@ 1 mm ( 4 @.@ 5 inches ) , a new record . Finally , previous rainfall had made the area wetter than normal and more prone to flooding . 
