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Powerful cyclone that brought cold, snow, hail to Korea heads to Japan

Published: 14 Apr. 2025, 22:11

A passerby holds firmly onto her umbrella due to strong winds in Gwangju on April 14. [YONHAP]

A powerful cyclone that brought unseasonal cold, snow, strong winds, hail and yellow dust to the Korean Peninsula and China over the weekend is now heading toward Japan.

On Monday, Japan’s Meteorological Agency warned that a mass of frigid air — with temperatures below minus 30 degrees Celsius (minus 22 degrees Fahrenheit) — is expected to flow above Honshu at an altitude of 5.5 kilometers (3.4 miles). The agency urged caution across the country, advising people to seek shelter inside buildings when storm clouds approach, as there is a risk of lightning, tornadoes, gusty winds and heavy rain.

The low-pressure system sweeping across Korea, China and Japan is a cut-off low, which refers to when the jet stream that circulates around the upper Arctic atmosphere becomes detached. When the polar jet stream turns into a meandering state like a snake and dips into the mid-latitudes, portions can break off and develop into separate low-pressure systems. These cyclones soon after trap polar air masses of minus 30 degrees or lower and rotate at high altitudes.

When such a cut-off low reaches the mid-latitudes during the warmer spring season, the stark temperature difference between upper and lower atmosphere layers — often up to 50 degrees Celsius — triggers intense convective activity. This leads to the formation of cumulonimbus, or thunderclouds, capable of producing downpours, thunder, lightning, hail and damaging winds.

The latest system brought record-setting winds in parts of China. According to China’s English-language, state-run Global Times, winds in Tianjin peaked at 43.2 meters per second on April 12 — the highest recorded in April since 1951. In Beijing, 843 trees toppled, and 30 vehicles and six homes were damaged. In Anhui Province, a 55-year-old woman was killed when a tree fell on her.

In Korea, gusts exceeding 20 meters per second were reported in several regions, causing damage to signs and structures. On Sunday, peak gusts in coastal areas such as Yeosu, South Jeolla; Yangyang, Gangwon; and Busan — as well as inland locations like Hwaseong, Gyeonggi — reached over 30 meters per second. Wind speeds of that magnitude are strong enough to knock over people, derail trains or uproot trees.

In Uijeongbu, Gyeonggi, a broken tree branch struck power lines, causing outages in 858 households. In Suwon, Gyeonggi, a falling signboard damaged a parked car.

While cut-off lows are not unheard of in spring, meteorologists in China have raised concerns that climate change is amplifying the severity of extreme weather during this season. Just before the system hit Beijing, daytime temperatures soared to 27 degrees Celsius — nearly summer levels. The greater the temperature difference between the upper and lower layers of the atmosphere, the more unstable air conditions become.

A firefighter tends to a collapsed tree in Suncheon, South Jeolla, on April 13. [NEWS1]

Japan also expects the inflow of warm, moist air accompanying the cut-off low will intensify weather conditions beyond forecasts. Experts warn that as climate change weakens and distorts the jet stream, these types of lows are likely to become more frequent.

In Korea, the low-pressure system is expected to continue influencing the weather through Tuesday, even when it passes through Japan. As of Monday afternoon, strong wind advisories were issued for the western coasts of Chungcheong and Jeolla, as well as the southern sea and cities, including Busan and Ulsan. Heavy snow warnings are in effect for mountainous areas of Gangwon.

“The scale of the low-pressure system is large enough to impact Korea even as it passes over Japan,” said an official from the Korea Meteorological Administration. “Rain and strong winds are expected to continue through the morning of Wednesday.”

Translated from the JoongAng Ilbo using generative AI and edited by Korea JoongAng Daily staff.

BY JEONG EUN-HYE [[email protected]]