On March 18, an unusual "winter typhoon" is hitting South Korea, causing extensive snowfall and fierce gusts because of a polar low-pressure system generated by extremely cold Arctic air. With temperatures dropping to as low as -40°C, this weather phenomenon is leading to severe blizzards throughout the nation. In Seoul, authorities have issued their most recent heavy snow alert ever recorded, predicting accumulations of up to 10 centimeters of snow. It’s worth noting that this is only the second instance in six years where such a potent polar low, characterized by wind velocities of around 20 meters per second—a strength akin to a tropical storm—has traversed the region.
On March 17, as reported by the Korea Meteorological Administration (KMA), a frigid air mass from the Arctic swept across the warmer waters of the West Sea during the night, leading to the formation of dense snow clouds. Consequently, much of South Korea faces severe snow warnings on March 18, surpassing Seoul's earlier record for the latest such alert established on March 9, 2010.
The forecast predicts snow accumulation ranging from 3 to 10 centimeters in Seoul and nearby districts, 3 to 30 centimeters in Gangwon Province, 1 to 15 centimeters in the Gyeongsang area, 1 to 10 centimeters in Chungcheong, 1 to 8 centimeters in the Honam region (including Gwangju and Jeolla provinces), and 1 to 5 centimeters atop Jeju Island's mountains. Snowfall rates could be as high as 3 to 5 centimeters per hour in Gangwon’s elevated zones, whereas other locations might face accumulations between 1 to 3 centimeters each hour. Additionally, some parts may receive rainfall amounting up to 10 to 20 millimeters.
Since March 16, Gangwon Province and the East Coast have experienced significant snowfall because of powerful easterly winds. By March 17, certain locations had recorded more than 40 centimeters of snow; specifically, Hongcheon saw accumulations up to 42.5 centimeters, Samcheok reported 38.4 centimeters, and Daegwallyeong measured 34 centimeters. Given forecasts predicting further snowfall, some parts may see totals typical for midwinter conditions.
The current snowstorm is caused by a polar low. The collision between freezing cold Arctic air and warmer sea temperatures of around 10°C generates extremely unstable weather patterns, leading to the formation of an intense rotating low-pressure area. As colder air is denser, it quickly descends, strengthening the whirlwind closer to ground level. Essentially, this phenomenon is known as a polar low—a type of low-pressure system born out of polar zones such as the Arctic region.
These systems unleash gale-force winds comparable to those seen during typhoons. Although typhoons necessitate wind speeds of at least 17 meters per second, some polar low-pressure systems advancing into land areas can create gusts as high as 20 meters per second. On March 18, powerful winds swept through Seoul, the metropolitan area, and Western parts of South Korea. As this system rapidly traverses the nation from west to east, it maintains wind velocities close to 15 meters per second, resulting in conditions similar to a typhoon but with snow rather than rainfall. The storm might also be accompanied by thunderstorms and lightning.
The chilly conditions will persist as the polar low-pressure system transports frigid Arctic air. On March 18, morning temperatures across the region will dip to between -3°C and 3°C, whereas afternoon readings will climb to somewhere within the span of 3°C to 9°C. Wind chills have plummeted to -4°C in Seoul and -8°C in Daejeon. Further cooling is anticipated for March 19th; overnight lows may plunge to anywhere from -6°C to 1°C, with peak daily temps oscillating around 6°C to 10°C.
For the first time in six years, since March 2019, a polar low has struck South Korea. During this event, severe gusts of wind accompanied by substantial snowfall blanketed Jeongseon in Gangwon with 15.9 cm, Pyeongchang received 15.1 cm, and Hongcheon experienced 14.3 cm. Similarly, winter-like precipitation impacted Gapyeong in Gyeonggi (accumulating up to 6 cm) as well as Bonghwa in North Gyeongsang Province (with an accumulation of 12.6 cm). Additionally, powerful winds led to the sinking of a 44-ton tugboat off the coast of Songi Island in Yeonggwang, resulting in one individual being reported missing. Furthermore, electrical outages forced a halt to operations on a Bundang Line train traveling between Wangsimni and Seoul Forest stations.