[Anchor]
During the ongoing hot weather, Gangneung and Sokcho experienced extreme tropical nights with minimum temperatures exceeding 30 degrees last night.
Two high-pressure systems bringing the heatwave are covering the Korean Peninsula, leading to a high possibility of prolonged heatwaves in the near future. Let’s find out more about the current situation with our reporting team.
Reporter Kim Mingyeong is here.
Firstly, let’s look at the tropical nights. Another extreme tropical night occurred?
[Reporter]
It occurred in Gangneung and Sokcho last night.
Gangneung experienced it for the second time following July 21st, while Sokcho had its first extreme tropical night this year.
Especially in Sokcho, the overnight minimum temperature was recorded at 30.6 degrees, making it the hottest night on record with the highest minimum temperature, breaking the record.
[Anchor]
We’ve heard of tropical nights, but extreme tropical nights are somewhat unfamiliar. When does it occur?
[Reporter]
A tropical night refers to when the minimum temperature does not drop below 25 degrees from 6 p.m. to 9 a.m. the next day.
An extreme tropical night refers to when the minimum temperature is above 30 degrees. The term “extreme tropical night” is a Japanese term, while the Korea Meteorological Administration only officially uses the term tropical night.
[Anchor]
Why is it not commonly used in Korea?
[Reporter]
It was a rare phenomenon in Korea. Tropical nights occur most frequently in Gangneung on the east coast of Gangwon Province.
Due to the phenomenon called the “Pyeon Effect,” where temperatures rise as the wind passes over the Taebaek Mountains, temperatures increase further. Since the observation of extreme tropical nights in Gangneung began in 1911, it has occurred only 13 times.
After first occurring in July 1942 with 31.1 degrees, it happened again in 2008, and the rest were observed after 2010. A notable point is that it has occurred three years in a row, with already two occurrences this year.
[Anchor]
However, it also occurred in Sokcho today. Is it occasionally observed in other regions as well?
[Reporter]
Yes. The overnight minimum temperature in Sokcho was recorded at 30.6 degrees, marking an extreme tropical night.
Sokcho last experienced this on August 4, 2018, with a minimum temperature of 30 degrees. Seoul also had extreme tropical nights during the unprecedented heatwave in 2018.
On August 1 and 2, 2018, it was observed for two consecutive days with minimum temperatures of 30.3 and 30.4 degrees. Although extreme tropical nights have only occurred in Gangneung and Sokcho so far this year, there is a possibility of nationwide occurrences in August.
[Anchor]
Extreme tropical nights have only occurred in Gangneung and Sokcho, while tropical nights have occurred throughout the country?
[Reporter]
Tropical nights occurred in 25 locations nationwide, where the overnight minimum temperatures exceeded 25 degrees.
Gangneung has been experiencing tropical nights for 10 consecutive days since July 19, while Seoul has had 8 consecutive tropical nights. Until yesterday, the nationwide average duration of tropical nights was 7 days. In the same period, the record-breaking heatwave in 2018 had 6 days, indicating that this year’s heatwave is progressing faster.
[Anchor]
Shall we also look at the heatwave situation during the day?
[Reporter]
Currently, a heatwave warning is issued for most regions across the country, except for some parts of Gangwon Province and mountainous areas in Jeju.
Heatwave alerts are in place for most inland areas, including southern Gyeonggi, Chungcheong, Honam, and Yeongnam. Seoul, which has been under a heatwave alert for four days, has been downgraded to a heat advisory since 10 a.m. today.
The sky in Seoul appears cloudier than in other regions, providing shade from the strong sunlight. However, the humidity remains high, and while it is not at an alert level, it will still feel hot and humid, with a perceived temperature of over 30 degrees.
[Anchor]
Why is it so hot these days?
[Reporter]
Let me explain with the weather map.
This is an upper-level weather map at 5 to 6km in the atmosphere.
The North Pacific High is completely covering Korea, while another weather map at 10 to 12 km shows the extension of a high-pressure system from northern China covering the peninsula.
In simple terms, just like being suffocated under a thick blanket, Korea is covered by thick layers of high-pressure systems, trapping hot air in the atmosphere.
[Anchor]
It’s not even August yet, but could this heat surpass the historic heatwave of 2018?
[Reporter]
In 2018, Hongcheon recorded 41 degrees, setting the record for the highest temperature. Seoul also recorded 39.6 degrees, the hottest in 111 years.
The unprecedented heatwave occurred because the North Pacific High developed earlier and stronger than the average year, leading to an early end to the rainy season. Additionally, with the strong development of the North Pacific and Tibetan Highs, the peninsula was completely covered from the upper to lower atmosphere.
However, this year, the timing of the North Pacific High’s expansion is later compared to 2018, and the rainy season has not officially ended yet, indicating a lower likelihood of extreme heat compared to 2018.
Nevertheless, with record-high temperatures and sea temperatures, there are still variables to consider.
[Anchor]
Let’s talk about rain. Why is it raining so heavily these days?
[Reporter]
Would you like to see some footage first?
These videos were submitted to YTN. On July 10, a video was filmed near Jamsil in Seoul. Clouds can be seen mainly in the north with cloud columns rising in some areas.
Another picture from Wonju, Gangwon Province, went viral on social media. Clouds developed strongly in one area, resembling a “spear-rain shower” due to the intense vertical development of rain clouds caused by the temperature difference between the scorching ground and the cold upper atmosphere during summer.
[Anchor]
Many people are wondering if the heavy showers during the daytime are microbursts. Can you clarify?
[Reporter]
The rain currently observed in Korea differs from microbursts.
Microbursts occur in low-latitude, tropical climates like Southeast Asia, where there is no cold air. During the daytime, the accumulated heat dissolves due to instability in the atmosphere, leading to the formation of strong rain clouds and rainfall.
As warm air continuously flows into Korea in the lower atmosphere and cold air descends in the upper atmosphere, these two different air masses collide, creating highly unstable conditions. When combined with the daytime heat, rain clouds develop even stronger.
So, it’s like squeezing a long towel in the bathtub. If you twist only the lower part, a little water may come out. This is the case with microbursts. However, twisting the entire towel all the way down will release more water. Similarly, in Korea’s case, the collision of cold air in the upper atmosphere adds to the characteristics of rainfall in our country.
[Anchor]
Lastly, let’s discuss the end of the rainy season.
The rainy season ends when the North Pacific High expands, completely covering Korea and pushing the front upwards.
As seen, the North Pacific High has extended to northern North Korea, indicating that the rainy season has practically ended.
However, the Korea Meteorological Administration mentioned that there are still variables related to the end of the rainy season and plans to announce an official position through tomorrow’s briefing.
*[Your report becomes the news]*
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