September 24, 2010 10:44
Torrential downpours drenched Seoul on Tuesday with the highest amount of rainfall the capital had seen since records began in 1908.
The Gangseo region in southwestern Seoul and Gangnam area in the southern part saw 293 mm of rainfall, while 18 out of 25 districts received more than 200 mm of rain. Seven districts in the city, including Dobong and Nowon, received a lower amount but were still pelted with between 95.5 mm to 194 mm of rain.
But the Korea Meteorological Administration failed to predict the extreme weather, forecasting between 20 mm and 60 mm of rain until 11 a.m. on Tuesday only two to three hours before the skies opened. Not until 2 p.m. when the Gangseo district had already seen 100 mm of rain per hour and Jongno was being drenched with 70 mm of rain that the KMA issued a weather advisory forecasting more than 200 mm precipitation.
It was a classical case of isolated torrential downpours, which are characterized by heavy rainfall concentrated in a particular area. The rain, 85 percent of which fell between 1 p.m. to 5 p.m. on Tuesday, flooded many parts of the capital.
The main reason was a clash between two different air masses near Seoul. "A cold and dry high pressure front from Mongolia and other northern regions and a warm and moist high pressure front from the northern Pacific formed a narrow band centering on Seoul," the KMA said. "As a result, a huge rain cloud formed in Seoul and neighboring regions." The culprit was typhoon Malakas. Typically during this time of the year, the north Pacific high pressure front is pushed south by a cold high pressure front from the north, but the typhoon, which was located near the equator, prevented the north Pacific high pressure front from traveling south and caused it to clash with a high pressure front from the north, resulting in the heavy rains.
The downpours overloaded Seoul's drainage systems. The Gwanghwamun intersection in central Seoul was flooded, as were thousands of homes at lower elevations. A Seoul city official said, "The main drainage pipes and pump stations in Seoul are designed to handle 75 mm of rain an hour, which happens once every 10 years, and were therefore unable to handle the record amount of rainfall in the metropolitan area.
Experts say Seoul officials must take another look at the city's drainage systems since heavy rains have become frequent due to the effects of climate change.
According to the National Emergency Management Agency, the downpours flooded a total of 14,018 homes, including 8,199 in Seoul, 3,024 in Incheon and 2,777 in Gyeonggi Province. Also, 2,706 homes saw power outages due to lightning, while 11,919 people were left homeless.
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