[Square] Hail, If It Could Be Predicted

"In the autumn of 1624 (the 2nd year of King Injo's reign), a severe hailstorm occurred in the region from Jangdan (northern Gyeonggi) to Pyeongsan (Namhae), with large hailstones the size of a bowl and smaller ones the size of eggs."

As can be seen from ancient historical records, hail has been a consistent meteorological phenomenon since the Joseon Dynasty or even much earlier. According to the Samguk Sagi, the size of hail varied widely, being compared to chestnuts or eggs, and occasionally, hailstones were so large that they killed cattle and horses tied up on farms. In the past, hail was a threatening presence that caused damage to crops and livestock.

The situation remains similar in modern times. Over the past year, we have frequently heard reports of crop damage caused by unexpected hail. In Korea, hail typically occurs in spring and autumn when there is a large temperature difference between the upper and lower atmosphere, usually with hailstones about 1 cm in size.

However, in 2021, hail was observed regardless of the season from April to November, and in August, hailstones larger than 4 cm were recorded in Tongyeong along with a typhoon landfall. Especially in October and November, during the fruit and crop harvest season, hailstones larger than 2 cm accompanied by strong winds caused damage to over 600 hectares.

Although not officially recorded as accidents or damage, hundreds of cases were reported on social networking services (SNS) throughout 2021 of people experiencing inconvenience due to sudden hail while vacationing in valleys or by the sea, or even during light walks near their homes.

Hail can develop rapidly within an hour and cause significant damage to specific areas. This was the case between May 31 and June 1, 2017, when hail fell on 25 cities and counties across 7 provinces of the Korean Peninsula.

Hail fell locally for about an hour, covering a damage area of 8,031 hectares, which is 27 times the size of Yeouido in Seoul, marking a record-breaking scale. Since precipitation clouds that generate hail can develop in as little as 30 minutes, it is difficult to accurately predict the exact time and location of hail occurrence.

Since June, the Korea Meteorological Administration (KMA) has been providing hail risk information via push notifications through the Weather Alimi application. These push alerts use 3D radar data and meteorological information to notify in advance, at the eup, myeon, and dong administrative levels, areas expected to experience hailstones larger than 2 cm that could damage crops and fruit trees.

From autumn, hail-prone area information can be viewed as videos on the KMA website. Utilizing this information will help prevent safety accidents not only in agricultural fields and orchards but also in transportation sectors such as roads and aviation.

With climate change causing frequent unusual extreme weather events, hail is no longer a rare or uncommon phenomenon in Korea. The theme of this year’s World Meteorological Day, selected by the World Meteorological Organization (WMO), is ‘Early Warning and Early Action.’ This reflects a global consensus on the need to recognize the seriousness of hazardous weather and to actively respond and prepare for it.

In this context, the newly introduced hail information service by the KMA is expected to provide early warnings of hail possibilities, enabling the public to prepare in advance and thereby minimize damage caused by hazardous weather.

Park Kwang-seok, Administrator of the Korea Meteorological Administration

This content was produced with the assistance of AI translation services.