[Weather] November snow for the first time in 117 years...Up to 20cm more tonight.

[Anchor]
This time, with a reporter, we will look into the cause of the November heavy snow and the weather forecast for the first time in 117 years.

Kim Min-kyung is in the YTN weather and disaster reporter studio. Welcome.

It never snowed so much in Seoul in November?

[Reporter]
That's right. In some parts of Seoul, snowfalls have been recorded more than 20cm, and ㅛ. The official snowfall in Seoul is based on the values measured at the weather station in Songwol-dong, Jongno. The year when it snowed the most in Seoul in November since the weather observation began was 1972. At that time, 12.4cm was recorded, and the amount of snow accumulated so far today was 18cm, which exceeded that record. Following the record of heavy snow in November for the first time in 117 years, a heavy snow warning was issued across Seoul today. It's been 14 years since January 4, 2010, when a heavy snow warning was issued in Seoul. In particular, the heavy snow warning was issued in November because the records before 1999 were difficult to confirm due to the Korea Meteorological Administration system, but it is the first time since then. [Anchor] There have been talks about why it's so hot in November, but why did the heavy snow fall all of a sudden?

[Reporter]
First of all, it's because of the cold air, not just the cold air, but the very strong cold air in the upper atmosphere. Shall we read the diary? I'll also show you a diary around the top 5km. The Korean Peninsula is here. So, around the Korean Peninsula and the central region, this yellow and red mass is the vortex of the upper cold air. Because of this whirlwind, it snowed like this. I prepared a video to explain it easily. You may have seen the water fall into a whirlwind when you take out the water plug after receiving water from the bathtub, but the cold air, like water draining from the bathtub, whirls down from the upper atmosphere to the ground in the shape of a funnel like an ice cream cone.

So, the cold air comes down from the north, and the cold air comes down from the top and the top, so the intensity of the cold is stronger than last week's sparkling cold. The problem with snow is that the air on the upper floor is colder than the air on the ground, and the colder the air, the heavier it is. As cold air comes down, clouds are created as the atmosphere becomes unstable as the cold air penetrates under the air that originally existed on the ground. The clouds made here became snow clouds, not rain clouds, because the temperature was so low.

[Anchor]
On top of that, the increased sea temperature due to warming also had a big impact?

[Reporter]
In general, when heavy snow falls in winter, one of the patterns is when there is a cold northwest wind from the northwest. In winter, the water temperature of the sea is warmer than the air temperature. Clouds develop as the cold wind passes through the relatively warm West Sea. Recently, the temperature of the sea around the Korean Peninsula has risen by 1.5 degrees in the past 100 years, which is 2.5 times higher than the global average. As a result, the temperature difference between the atmospheric temperature and seawater temperature widens, resulting in stronger cloud development.

[Anchor]
It's about 5:10 now. I think the way home from work will overlap now, what is the snow situation on the way home from work?

[Reporter]
Yes, let's look at the radar screen where you can see the movement of the snow clouds.It's a snow cloud at this time of the year. Seoul is a little out now, but snow clouds continue to come in from the northwest inland like this. Rain clouds are expected to continue to flow in like this on the way home from work, so traffic safety needs to be paid attention in places such as southern Gyeonggi Province and Chungcheong Province.

[Anchor]
But there's one more crisis tonight?

[Reporter]
That's right. I'll explain it by looking at the diary once again. It's a 5km situation on the top floor. As this low pressure turns counterclockwise, strong snow clouds are expected to enter the central part of the country and this time to parts of the southern part of the country again between tonight and tomorrow morning. This depression is called a trough, and clouds develop well here. Originally, the low pressure had to move from west to east, but the flow of the upper layer is very stagnant. That's why the low pressure keeps spinning like a cog in place, so now a rain cloud is coming in from the front end of the barometric valley, and I think the full-fledged barometric valley will affect Korea once again tonight.

[Anchor]
It falls more than 20cm in the Seoul metropolitan area? You're going to have to be prepared all night, but there are areas you need to be especially wary of?

[Reporter]
That's right. It's inland from Chungcheong. As mentioned earlier, as the cold northwest wind passes through the West Sea, snow clouds develop and snow falls on the west, especially on the west coast. The problem is that there are times when a lot of snow suddenly falls in Daejeon, Asan, Cheonan, and Cheongju, which are not in this area, but in the downtown areas of Chungcheong. It's called the "Asan Bay Effect." Do you want to see the graphic? When the wind blows below 290 degrees, snow clouds develop as they pass through the West Sea, so a lot of snow falls near the west coast of Chungnam or Honam. The problem is that when the wind direction is a little further north, and when it is 310 degrees or higher, clouds pass through Gyeonggi Bay, Asan Bay, and immediately enter Chungcheong inland. The problem is that the width of this cloud is very narrow, like a rain cloud in the shape of a rainy season band, making it very difficult for supercomputers to predict.

[Anchor]
That's why it's hard to predict. Are you saying that heavy snow falls in a short period of time in the Chungcheong area?

[Reporter]
That's right. Shall we look at the screen? You've seen a lot of these clouds during the rainy season. It is a cloud that develops strongly only in narrow and narrow areas. Let's look at the screen. This Asan Bay effect is quite high at 4-7 degrees, but this Gyeonggi Bay and Asan Bay are slightly lower at 0 to 3 degrees, so this narrow and thin band-shaped rain cloud band enters Chungcheong inland. Around December 30, 2020, snow accumulated in an instant of about 10cm in a short period of three hours in some parts of Sejong. Because of this, it's something you have to be very careful about.

[Anchor]
So heavy snow falls in Chungcheong inland in a short period of time, right?

[Reporter]
That's right.

[Anchor]
I'll have to be careful. Until when do you think it will snow this time?

[Reporter]
After overcoming the crisis once from tonight to tomorrow morning, it is expected to show a lull everywhere from tomorrow afternoon. However, snow clouds are expected to follow even after the barometric pressure trough, so southern Gyeonggi Province is expected to continue until late tomorrow night, and Chungcheong, Honam, and Jeju Island are expected to continue until the day after tomorrow.

[Anchor]
Then I'm worried about going to work tomorrow, so can I drive out?

[Reporter]
That's the biggest concern. This is because there are a lot of snow accumulated and it is cold during the day, so there are likely to be many areas where the accumulated snow does not melt and freezes as it is. Even in the middle of the day, the temperature in Seoul is still very low at 0.4 degrees. However, the temperature drops further tomorrow and the day after tomorrow. In Seoul, it will drop to minus 2 degrees Celsius tomorrow and minus 4 degrees Celsius the day after Friday. You won't worry too much on roads with good snow removal work, but you should pay special attention to icy roads on side roads and riversides, and especially invisible "road thin ice."

[Anchor]
And I heard it's heavy snow this time. What's the difference?

[Reporter]
Heavy snow' is called wet snow as clouds pass over the sea and wet snow. It's very humid, so it clumps up well. However, on the contrary, dry and squishy snow is called construction. There is a big difference in weight between this construction and wet snow, even if the same amount of snow falls. When 1m of snow accumulates in a space of 1m in width and length, the difference is almost twice as light snow, that is, 150kg for construction and 300kg for heavy wet snow. In particular, if 50cm of wet snow accumulates in a general greenhouse, the weight will soar up to 30 tons. There are two 15-ton trucks and 30 electric poles.

[Anchor]
It's said that up to 20cm more snow could fall tonight as well. I think we need to be thoroughly prepared. We've been with reporter Kim Min-kyung. Thank you very much. Thank you.