Taiwan experiences 1st full week of 'extremely heavy' rain since 1998

Taipei, Aug. 4 (CNA) Taiwan saw its first full week of "extremely heavy" rain since 1998 last week, the Taiwan's Central Weather Administration (CWA) said Monday.

According to the CWA, extremely heavy rain is defined as when "24-hour accumulated rainfall exceeds 200 millimeters, or 3-hour accumulated rainfall exceeds 100 mm."

The CWA made the revelation at a news conference after lifting the weeklong rain advisory which the CWA had named the "0728 Southwesterly Airflow Extremely Heavy Rain Incident."

At the presser, the CWA's director of the weather forecasting center Chen Yi-liang (陳怡良) said the week between July 28 and Aug. 4 was the first time since 1998 when observation stations in the central and southern parts of Taiwan measured over 200 mm of rain every day.

Chen said that both short bursts and extended rain blanketed the entirety of southern and central Taiwan, with 17 municipalities across Nantou, Yunlin, Chiayi and Pingtung counties as well as Tainan and Kaohsiung experiencing extremely torrential rain, which, according to the CWA, is when "24-hour accumulated rainfall exceeds 500 mm."

Chen went on to explain that during the week, certain areas saw torrential rain when precipitation reached over 200 mm in three hours.

Such weather patterns lasted for five days straight in a number of locations in the center and the south, Chen said, adding that the accumulated calculation of rain came close to the record set by Typhoon Morakot in 2009.

According to CWA statistics, the 2009 typhoon set a record of 3,060 mm over five days clocked in at Chiayi County's Alishan Township.

From July 28 to 2 p.m. Aug. 4, the most amount of rain observed was 2,873.5 mm in Kaohsiung's Duona forest trail, according to the CWA.

At the Monday presser, Chen said that rain reached torrential and "extremely torrential" levels in certain areas in two waves, the first between July 28 and 31 and the second from Aug. 1 to 3

Chen said the main reason behind the weeklong rain was due to the changes between strengthening and weakening of southwesterly airflow above the Bashi Channel.

The effects of the airflow was most prevalent between last Wednesday and Thursday when it covered central and southern Taiwan in significant rainfall.

Due to the decreased chance of large-scale and drastic heavy rain, the CWA lifted the advisory of the week-long rain at noon Monday.