The Central Weather Bureau lifted both the sea and land warnings for Tropical Storm Talim yesterday, but warned extremely heavy to torrential rain was likely to occur in central and southern areas because of the southwest monsoon.
The bureau downgraded Talim to a tropical depression, which was moving northeastward near the southern coast of South Korea.
Bureau forecaster Lin Hsiu-wen (林秀雯) said the southwesterly monsoon would gradually weaken today and tomorrow. While the rain was expected to ease, some regions should still be prepared for the possibility of heavy or extremely heavy rain, Lin said.
While Talim had weakened and moved away from Taiwan, residents in the south were still suffering from damage to roads and other infrastructure caused by the torrential rain. Flooding could still be seen in rural areas yesterday.
Two people died and one was injured amid the havoc wreaked by the storm, according to the Central Emergency Operation Center.
The bureau originally forecast that the accumulated rainfall in mountainous areas of southern Taiwan could reach 1,200mm to 1,500mm and that mountainous areas in central Taiwan could see 700mm to 1,100mm.
However, those estimates were higher than the actual rainfall and the bureau on Wednesday night had to quickly adjust its forecast down to between 800mm and 1,200mm in mountainous areas in the south and between 600mm to 900mm in central Taiwan.
Lin said rainfall estimates continue to be a major challenge for forecasters.
“We cannot afford to underestimate the dual influence of a tropical storm and the southwesterly monsoon,” she said. “In view of the disasters they could potentially bring, we decided to issue a rainfall estimate, like we did when another southwesterly monsoon hit the nation last week.”
Lin said that Talim moved faster than expected and its power continued to weaken as it moved away. The southwest monsoon caused only sporadic rather than continuous rain, causing the rainfall to accumulate much more slowly than last week, she said.
Statistics from the bureau showed the accumulated rainfall in Greater Kaohsiung’s Taoyuan District (桃源) from Monday to Thursday was 741mm. The accumulated rainfall in Chunrih (春日) and Majia (瑪家) townships in Pingtung County were 678mm and 590mm respectively.
Daniel Wu (吳德榮), former director of the bureau’s forecast center, said he did not think the bureau was to blame for overestimating the rainfall.
“In the past, the bureau would only give rainfall estimates after the typhoon arrived, which would be subject to change every three hours,” Wu said.
“The earlier you give the estimate, the greater the likelihood of error,” he added.
He said the bureau estimated the highest rainfall would be between 1,200mm and 1,500mm, but media had only focused on the 1,500mm part.
The bureau must take various factors into consideration when it makes rainfall estimates and the numbers need to be adjusted constantly depending on the actual situation, he said.
“The monsoon will continue to affect the nation for two more days, so who knows if the nation will see more rain?” Wu said.