Rain, wind, thunder and lightning forecast for central regions

Visitors to Seoul Forest use a picnic mat to escape a shower on Tuesday afternoon. [YONHAP]

Heavy rain accompanied by strong winds, thunder and lightning will affect the central regions including the Seoul metropolitan area over the next couple of days, the national weather agency announced Thursday.

According to the Korea Meteorological Administration (KMA), rainstorms are expected to begin Thursday night and linger through early Friday morning before spreading to northwestern North Gyeongsang.

Weather officials also warned of the possibility of hail.

Between Thursday and Friday, the Seoul metropolitan area — Seoul, Incheon and Gyeonggi — northern North Gyeongsang and western Gangwon are forecast to get 10 to 50 millimeters (0.4 to 2 inches) of rain, with an hourly maximum of 20 to 30 millimeters of rain.

Some parts of Seoul could see more than 60 millimeters of rainfall in the two-day period, said the KMA.

Eastern Gangwon, southern South Chungcheong, southern North Chungcheong and northwestern North Gyeongsang are predicted to get 5 to 20 millimeters of rainfall between Thursday and Friday, while South Jeolla and North Jeolla are predicted to receive less than 5 millimeters.

Showers are expected sporadically in the Seoul metropolitan area on Saturday and Sunday.

The cloudy weather will likely persist throughout most of the country until Tuesday.

In Seoul on Friday and Saturday, the low is forecast to be 18 degrees Celsius (64.4 degrees Fahrenheit) and the high 28 degrees Celsius. On Sunday, the low will likely be 19 degrees and the high 28 degrees.

By and large, nationwide temperatures next week will be about the same as in previous years or slightly higher by up to three degrees Celsius, possibly reaching up to 32 degrees in some regions.

The upcoming sporadic rainfall is attributed to atmospheric instability caused by a stationary low-pressure system located north of the Korean Peninsula, which brings cold air from the north down into the atmosphere, weather officials explained.

“The cold air in the upper atmospheric layers descends to the surface, while the warm air heated at the surface rises,” said Park Jung-hwan, a meteorological analyst at the KMA. “The interaction between these two air masses with different properties creates highly unstable atmospheric conditions.”

As for Typhoon Guchol, which was seen passing through the Philippine Sea on Thursday afternoon, weather officials said it probably won’t affect Korea but rather travel westward across Japan’s southern waters.

BY JEONG EUN-HYE, LEE SUNG-EUN [lee.sungeun@joongang.co.kr]