Why Did a Summer's Worth of Rain Fall in Two Days? Behind the 912mm Deluge

[Anchor]

The record-breaking torrential rain that battered South Gyeongsang Province was caused by a low-pressure system formed after Typhoon Dolphin dissipated.

Reporter Jeong Gu-hui explains why such extreme downpours pounded South Gyeongsang Province and how much longer the rain is expected to continue.

[Reporter]

What brought the heavy rain to the South Gyeongsang region today (August 17) is a low-pressure system.

Low-pressure systems rotate counterclockwise in the Northern Hemisphere.

As a result, southwesterly winds blow on the eastern side of the low-pressure system, pumping up warm water vapor from the south.

Looking at the radar imagery from 2 a.m. today, when heavy rain was pouring in Geoje, strong southwesterly winds were indeed blowing, confirming that rain clouds formed over the South Sea were flowing into the southern coast of South Gyeongsang Province.

In particular, it can be seen that these clouds developed even more strongly the moment they hit Geoje.

What is the reason?

Water vapor flows in carried by the wind.

However, when strong winds enter inland areas, their speed drops sharply due to friction with the ground.

As the inflow speed of water vapor suddenly slows down, more water vapor accumulates than escapes, causing lower-level convergence. This leads to the development of intense rain clouds.

Simply put, the amount of water vapor surges due to a bottleneck effect.

As a result, a torrential downpour of 912 mm was dumped on Geoje over the past two days—yesterday and today—while Busan recorded 222 mm and Miryang, which suffered from severe drought, recorded 132 mm, showing that precipitation surged closer to the coast.

Geoje's average summer precipitation is 935 mm, meaning that a full season's worth of summer rain poured down in just two days.

In addition, the current water temperature of the southern coast is around 28°C (82°F), and the warm sea supplying more water vapor is also pointed to as a contributing factor.

Furthermore, blocked by a high-pressure system stationed over Japan, the low-pressure system could not move eastward and its stagnation prolonged, continuously generating rain clouds under its influence.

Since it is expected to completely move out of the influence of this low-pressure system by tomorrow, up to 60 mm of additional rain is forecast for the southern coast of South Gyeongsang Province, and up to 30 mm for the inland areas of South Gyeongsang and southern North Gyeongsang Province through tomorrow.

(Video edited by: Kim Jin-won, Design by: Park Tae-young)
※ Please note: This article was translated by AI and may contain errors.