Typhoon Mitag, known in the Philippines as Typhoon Onyok, was a moderately strong tropical cyclone that severely affected

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the nort ...

East China East China () is a geographical and a loosely defined cultural region that covers the eastern coastal area of China. A concept abolished in 1978, for economical purposes the region was defined from 1949 to 1961 by the Chinese Central Governme ...

and

South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...

in early October 2019. The 23rd depression and the 8th typhoon of the

2019 Pacific typhoon season The 2019 Pacific typhoon season was the costliest Pacific typhoon season on record, just ahead of the previous year. The season featured fairly above-average tropical cyclone activity for the second consecutive year, producing 29 named storms, ...

, Mitag developed from a low pressure system near the Micronesia Islands on September 24. Tracking generally northwestward, the system gradually organised and the

Japanese Meteorological Agency The , abbreviated JMA, is an agency of the Ministry of Land, Infrastructure, Transport and Tourism. It is charged with gathering and providing results for the public in Japan that are obtained from data based on daily scientific observation and ...

issued its first advisory on Tropical Depression 19W on September 27. It continued northeastward, gradually organizing and becoming less broad. It was then upgraded to Tropical Storm Mitag on September 28. The storm quickly intensified, becoming a Category 1 typhoon just a day later. It further intensified into a Category 2 typhoon, passing very close to

. It weakened thereafter, making landfall near

Zhoushan Zhoushan , formerly romanized as Chusan, is an urbanized archipelago with the administrative status of a prefecture-level city in the eastern Chinese province of Zhejiang. It consists of an archipelago of islands at the southern mouth of H ...

in East China on October 1 before weakening back to a poorly organized tropical storm. It later made landfall in South Korea on October 2 before becoming

extratropical Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are low-pressure areas which, along with the anticyclones of high-pressure areas, drive the weather over much of the Earth. Extratropical cyclones are capable of p ...

in the

Japan Sea The Sea of Japan is the marginal sea between the Japanese archipelago, Sakhalin, the Korean Peninsula, and the mainland of the Russian Far East. The Japanese archipelago separates the sea from the Pacific Ocean. Like the Mediterranean Sea, it h ...

on October 3.

Meteorological history

Mitag developed from a low pressure system near the Micronesia Islands on September 24. Tracking generally northwestward, the system gradually organised and the

issued its first advisory on Tropical Depression 19W on September 27. Traipsing toward the Philippines and eventually entering the Philippine Area of Responsibility the next day with the Philippine Atmospherical, Geological and Astronomical Services Administration routinely named it Onyok. The JMA followed suit after the system intensified to become a tropical storm, naming it Mitag on September 28. The JTWC's projected track path lead Mitag toward the

Ryukyu Islands The , also known as the or the , are a chain of Japanese islands that stretch southwest from Kyushu to Taiwan: the Ōsumi, Tokara, Amami, Okinawa, and Sakishima Islands (further divided into the Miyako and Yaeyama Islands), with Yonaguni ...

, all while strengthening. Mitag, while gaining latitude, strengthened quickly on September 29 and within just hours became a severe tropical storm, and shortly after, a category 1 typhoon later on that same day. Mitag 2019-10-02 0235Z

Developing a visible circulation and with thick bands of strong convection, it swiftly became a category 2 typhoon on the evening of September 30, with a small, clouded eye developing as it passed just east of

. Due to a sudden increase in wind shear and decrease in

sea surface temperature Sea surface temperature (SST), or ocean surface temperature, is the ocean temperature close to the surface. The exact meaning of ''surface'' varies according to the measurement method used, but it is between and below the sea surface. Air mass ...

s, Mitag began to quickly degrade after becoming a category 2 typhoon, and weakened to a category 1 typhoon before making its first mainland landfall on

, exiting the Philippine Area of Responsibility. The land interaction disrupted Mitag by quite some margin, and it weakened to a tropical storm relatively quickly during landfall. It quickly moved northeast towards South Korea as it began to enter its

transition on the evening of October 1. Mitag made its second landfall on South Korea on October 2 whilst surprisingly holding onto tropical storm strength and remaining a poorly organized tropical cyclone. Shortly after land interaction with South Korea, its low-level circulation center was continually exposed by westerly wind shear and its cloud tops became displaced, leading to it weakening below tropical depression status on October 3 and becoming

the next day.

Preparations and Impact

The Philippines

As Mitag was initially forecast to come near the Philippines, a Signal 1 warning was raised for a portion of

Luzon Luzon (; ) is the largest and most populous island in the Philippines. Located in the northern portion of the Philippines archipelago, it is the economic and political center of the nation, being home to the country's capital city, Manila, as ...

and the

Batanes Batanes, officially the Province of Batanes ( ivv, Provinsiya nu Batanes; Ilocano: ''Probinsia ti Batanes''; fil, Lalawigan ng Batanes, ), is an archipelagic province in the Philippines, administratively part of the Cagayan Valley region. It i ...

and the

Babuyan The Babuyan Islands ( ), also known as the Babuyan Group of Islands, is an archipelago in the Philippines, located in the Luzon Strait north of the main island of Luzon and south of Taiwan via Bashi Channel to Luzon Strait. The archipelago consi ...

Islands as the storm passed just northeast of the country as a category 1 typhoon. The PAGASA also noted that in its path it would bring showers and isolated thunderstorms over the

Cagayan valley Cagayan Valley ( ilo, Tanap ti Cagayan; fil, Lambak ng Cagayan), is an administrative region in the Philippines, located in the northeastern section of Luzon Island. It is composed of five Philippine provinces: Batanes, Cagayan, Isabela, Nue ...

in its passing, and rough sea conditions as well. As forecast, the storm's outer bands produced heavy rainfall, rough sea conditions, and gusty winds in Northern Luzon, but no damage was reported.

Taiwan

As Mitag approached Taiwan from the southeast, an Orange Tropical Cyclone Alert was raised for Taiwan on September 29, the second-highest possible. On the same day, the Taiwanese government ordered a total closure of all financial markets and schools in the country as Mitag advanced towards Taiwan, while airlines in the country also cancelled dozens of flights amid warnings of floods and high winds issued by the country's meteorological agency.

South Korea

References