Typhoon Jangmi, the season's sixth typhoon, is moving northeast from waters southwest of Okinawa, Japan, and is expected to indirectly affect South Korea by pushing in hot and humid air. Rain is forecast on Jeju Island and in southern regions on Friday and Saturday, while southeasterly winds carried by the typhoon will turn hot and dry as they pass over mountain ranges, bringing a heat wave to the Seoul metropolitan area on Saturday.
According to the Korea Meteorological Administration on Friday, Typhoon Jangmi was passing through waters about 250 kilometers south-southwest of Okinawa as of 9 a.m. that day, moving northeast. The typhoon is expected to strengthen to category 3 (strong) by Friday evening.
Rain will begin in Jeju before expanding to South Jeolla and South Gyeongsang provinces by Friday night. By early Saturday, the rain will extend to North Jeolla and southern North Gyeongsang provinces, before tapering off in North Jeolla by morning and in South Jeolla, southern North Gyeongsang, South Gyeongsang and Jeju by the afternoon.
Expected precipitation is 30 to 80 millimeters in Jeju (more than 150 millimeters in heavy mountainous areas and more than 120 millimeters in heavy non-mountainous areas), 20 to 60 millimeters in Gwangju, South Jeolla, Busan, Ulsan and South Gyeongsang (more than 80 millimeters in heavier areas of southern South Jeolla, Busan, the southern coast of South Gyeongsang and southwestern inland South Gyeongsang), 5 to 20 millimeters in southern North Jeolla, 5 to 10 millimeters in Daegu and southern North Gyeongsang, and around 5 millimeters in northern North Jeolla.
From Friday night through Saturday morning, as the influence of an upper-level atmospheric trough strengthens, heavy rainfall of 20 to 30 millimeters per hour may pour down at times, especially on Jeju and along the southern coast, requiring precautions to prevent damage.
Strong winds and high waves are expected on the southern seas due to Typhoon Jangmi. Swell waves are also expected to flow into Jeju Island and the southern coast, requiring caution against maritime safety accidents.
The Seoul metropolitan area and other northwestern parts of the country will become hotter due to the southeasterly winds blowing from the typhoon. This is because of the "föhn phenomenon," in which air becomes hot and dry as it crosses mountains.
Daytime temperatures in Seoul and other parts of the metropolitan area are expected to climb to 33 degrees Celsius on Saturday. However, a heat wave advisory is not expected to be issued, as humidity will not be high and the apparent temperature is forecast to be lower than the actual temperature. On Monday, an atmospheric trough is expected to pass over the northern part of the country, bringing showers to inland central regions and lowering temperatures to seasonal averages.
