15°C temperature swings, possible fall typhoon

Clear fall weather will bring chilly mornings and warm afternoons this week, while a potential typhoon remains under watch for later this month.

Korea can expect typical fall weather throughout this week. Temperatures could swing by as much as 15 degrees Celsius (27 degrees Fahrenheit) between chilly mornings and warm afternoons.

A potential fall typhoon moving north, however, could disrupt the stretch of mild, settled weather after this week.

Seoul’s morning low fell to 19.3 degrees Celsius (66.7 degrees Fahrenheit) on Monday, according to the Korea Meteorological Administration (KMA). The daily high reached 26.1 degrees Celsius.

The southern parts of the country saw highs around 30 degrees Celsius. 

The wide gap between daytime and nighttime temperatures is expected to persist for the time being.

Clear skies are forecast to push Seoul’s daytime temperature to 29 degrees Celsius on Wednesday. A much cooler night is expected to create an even wider temperature swing.

Rain is expected on Jeju Island on Friday and Saturday, according to the KMA’s medium-range forecast. Most of the rest of the country should see mostly clear or cloudy skies through the weekend.

“Daytime and nighttime temperatures will differ by 10 to 15 degrees Celsius across most of the country for the time being,” the KMA said.

One of the biggest uncertainties that could disrupt the settled fall weather is a potential typhoon.

A total of 10 typhoons developed last month, the most on record for the month. An unusually active typhoon season this summer depleted much of the water vapor over tropical waters. At the same time, ocean temperatures have fallen somewhat and left less energy available for new typhoons.

Recently, however, tropical disturbances that can develop into typhoons have begun appearing again. This has raised the possibility of renewed activity.

Some numerical weather models project that a tropical disturbance in the western Pacific, named “Invest 90W,” could develop into a typhoon and move north toward waters south of Japan around this weekend.

It is too early to tell whether the disturbance will develop into a typhoon or what path it might take. Even so, experts say the possibility of a fall typhoon should not be overlooked.

“The energy depleted over the summer is building back up, so we are entering another period when we need to watch closely for typhoons moving north,” said Kang Nam-young, a climatology professor at Kyungpook National University. “In the fall, the jet stream can create a path that steers typhoons toward the Korean Peninsula, so we need to remain vigilant through September, the peak of typhoon season.”

BY CHON KWON-PIL [lee.soojung1@joongang.co.kr]