Korea braces for 'water bomb' as Typhoon Pulasan approaches

Typhoon Pulasan, the 14th typhoon of the season, is expected to bring heavy rainfall of up to 300 millimeters (11.8 inches) and typhoon-level winds across the country through the weekend.

Monitor at the Central Disaster and Safety Countermeasure Headquarters at the Government Complex Seoul in Jongno District, central Seoul [NEWS1]

Typhoon Pulasan, the 14th typhoon of the season, is expected to bring heavy rainfall of up to 300 millimeters (11.8 inches) and typhoon-level winds across the country through the weekend.

Rainfall alerts gradually expanded across most regions of the country on Friday, according to the Korea Meteorological Administration (KMA). From midnight to 4 p.m. on Friday, Mount Halla in Jeju received 289.5 millimeters of rain, Suncheon in South Jeolla saw 166 millimeters, and Sancheong in South Gyeongsang recorded 140 millimeters.

Heavy rain warnings have been issued for the five islands of the Yellow Sea and the eastern regions of Gangwon, while Seoul and some parts of the central and southern areas are under heavy rain watch.

The KMA issues heavy rain watches when precipitation is expected to exceed 60 millimeters for three hours or 110 millimeters for 12 hours. The numbers are increased to 90 and 180, respectively, for heavy rain warnings.

Firefighters rescue individuals who were trapped in a building following a nearby road flooding in Paju on July 18. [NEWS1]

Nation braces for 300-millimeter 'water bomb'

The rain is expected to continue until Sunday, and its intensity will likely exceed initial predictions. This is because Typhoon Pulasan, which made landfall in China and weakened into a tropical depression, is now heading toward the southern part of the Korean Peninsula. The tropical depression is expected to pass between Jeju and the south coast via the Yellow Sea on Saturday. It will add heat and moisture to the peninsula, potentially causing heavy rainfall.

"A large amount of moisture is flowing into the front of the tropical depression, while cold air is descending from the north, so we expect a strong rain band to form from the collision of cold and warm air masses," said Gong Sang-min, an official from the Korea Meteorological Administration.

Rain clouds are likely to concentrate on the east coast and mountainous areas of Gangwon, where some areas are expected to record cumulative rainfall of over 300 millimeters. The southern coast of South Gyeongsang may also see over 200 millimeters of rain, while Seoul and the surrounding metropolitan area are expected to receive up to 150 millimeters. Although the rain will gradually subside on Sunday, it may continue in the eastern regions of Gangwon and southern areas of the Korean Peninsula until nighttime.

Firefighters respond to flooded areas in South Gyeongsang on July 14. [GYEONGSANGNAM-DO PROVINCIAL FIRE HEADQUARTERS]

Watch out for winds and lightning

In addition to the rain, typhoon-level winds are expected as the tropical depression passes. Powerful winds exceeding 70 km per hour are forecast for Jeju and the southern coast over the weekend, while winds in other regions may reach around 55 km per hour, raising concerns about wind damage. There is also a possibility of lightning accidents in some areas.

"Strong winds could disrupt aircraft and ship operations," said Gong. "It's crucial to thoroughly inspect structures like high-rise construction sites, greenhouses, banners, wind turbines, and electric pylons." He also urged precautions for coastal areas, as high tides are expected until Saturday due to the lunar gravitational pull, increasing the risk of flooding in low-lying coastal regions.

Cheonggyecheon trail is flooded with rain as heavy downpour drenched Seoul on July 17. [YONHAP]

Temperatures to drop 10 degrees in two days

Along with the autumn downpour, temperatures will drop sharply. According to the KMA, Saturday and Sunday will be three to five degrees lower than Friday, with temperatures close to this year’s average highs of 23 to 27 degrees.

In Seoul, the daytime high is expected to remain at 21 degrees on Saturday. This marks a drop of over 10 degrees from the 32.6 degrees recorded on Thursday in two days. Morning temperatures will also drop below 20 degrees, bringing a cool breeze.

Typical autumn weather is expected to continue next week, with most daytime temperatures staying below 30 degrees nationwide and temperature differences between day and night widening by about 10 degrees.

BY CHUN KWON-PIL, KIM MIN-YOUNG [kim.minyoung5@joongang.co.kr]