Typhoon Krathon


Typhoon Krathon, known in the Philippines as Super Typhoon Julian, was a powerful and erratic typhoon which impacted Taiwan and the Philippines in late September and early October 2024. Krathon, whose name refers to the santol fruit, was the first storm to make landfall on Taiwan's densely populated western plains since Typhoon Thelma in 1977. It was also the first storm to hit Kaohsiung in October and the first since Tropical Storm Trami in 2001 to weaken into a tropical depression over Taiwan. Additionally, it was the wettest tropical cyclone in Basco, Batanes, bringing more than two months' worth of rainfall for September and surpassing the previous record set by Typhoon Ruth in 1991 and the strongest typhoon to hit the province since Typhoon Chanthu in 2021.
The eighteenth named storm, the second violent typhoon of the season, and the second super typhoon of the annual typhoon season, Krathon developed into a tropical depression near Kadena Air Base, Japan, on September 26, and was classified as a tropical storm by the Japan Meteorological Agency on September 28 as it moved southwestward along the southeastern periphery. Krathon reached minimal typhoon status on September 29 after developing a broad, ragged eye. The typhoon moved north-northwestward between two subtropical highs before shifting west-northwestward and passing near Sabtang, Batanes. Early on October 1, the JMA reported that the storm had reached its peak intensity, with ten-minute sustained winds of and a central pressure of. It subsequently peaked as a Category 4-equivalent super typhoon on the Saffir-Simpson scale, with one-minute sustained winds of. As Krathon moved into the northern South China Sea, an eyewall replacement cycle began, which was evident in radar imagery, with the secondary eyewall nearly encircling the inner eye. Once the eyewall replacement cycle was complete, Krathon began warming cloud tops and displayed a weakened cloud-filled eye feature that caused upwelling and a decrease in ocean heat content. On October 3, Krathon made landfall near Siaogang District in Kaohsiung, Taiwan, with its spiral bands of deep convection gradually weakening as it moved north-northeastward into central Taiwan, near the western edge of the Central Mountain Range. After making landfall, the system rapidly slowed down and deteriorated, exhibiting minimal convective activity. The JMA continued to monitor the system as it emerged over the South China Sea before dissipating on the same day.
Ahead of the storm, a Tropical Cyclone Wind Signal was issued for various areas in the Philippines, with a red alert for Calayan and Santa Ana in Cagayan. Krathon resulted in at least five deaths, three people missing, and eight injured in the Philippines. Meanwhile, Taiwan's Central Weather Administration issued maritime warnings for the Bashi Channel, leading to the evacuation of more than 11,000 people and the mobilization of nearly 40,000 soldiers for rescue efforts; at least 13 people were killed across the island, including nine from the Antai Tian-Sheng Memorial Hospital fire in Pingtung County. Overall, 18 people were killed, 731 were injured and one was missing by Krathon, leaving at least US in damages.

Meteorological history

The origins of Typhoon Krathon can be traced back to September 26, when the Japan Meteorological Agency reported a tropical depression south-southwest of Kadena Air Base, Japan, characterised by a partially exposed low-level circulation centre with persistent deep convection in the southern semicircle and formative banding to the north. The United States Joint Typhoon Warning Center issued a tropical cyclone formation alert on September 27, noting that convective banding was wrapping into the centre and that the environmental analysis indicated a favourable environment for development due to low vertical wind shear, good equatorward outflow aloft, and warm sea surface temperatures of. On that same day, the Philippine Atmospheric, Geophysical and Astronomical Services Administration announced that the system had developed into a tropical depression named Julian, as it formed within the Philippine Area of Responsibility; the depression was moving slowly south-southwestward due to weak steering flow.At 09:00 UTC, the JTWC upgraded the tropical depression, designating the system as 20W, noting an obscured low-level circulation centre that was assumed to be in the centre of rotating bands of convection organising into vortical hot towers. Satellite imagery indicated that the storm was steadily consolidating, with spiral bands of deep convection extending across three quadrants of the system and encircling the low-level circulation centre. On September 28, the depression intensified into a tropical storm named Krathon by the JMA, fueled by low vertical wind shear, warm sea surface temperatures, and high ocean heat content, while moving southwestward along the southeastern periphery of a mid-level subtropical high; however, Krathon slowed down over the last six hours and was located within a col region between two deep-layer subtropical highs, with satellite imagery indicating an improving appearance due to the development of a central dense overcast feature over the circulation centre.File:Radar imagery of Typhoon Krathon from the Taiwan Central Weather Administration.webm|left|thumb|244x244px|CWA radar imagery of Krathon tracking over the Balintang Channel before eventually making landfall over the southwestern coast of Taiwan
At around 18:00 UTC, the JMA upgraded the system to a severe tropical storm, utilizing the Dvorak technique to assess its intensity based on satellite imagery. Krathon displayed strong equatorward outflow alongside a weaker polar channel, while the observed cirrus cloud suggested that a more radial outflow was beginning to develop as the system intensified. Early the next day, both the JMA and the JTWC upgraded it to a minimal typhoon after it had opened a broad, raggedly-defined eye, which had since become cloud-filled, and the system was moving north-northwestward between two mid-level subtropical highs. On September 30, Krathon's eye, measuring in diameter, was visible on infrared satellite imagery, surrounded by warm temperatures of, as the storm gradually moved west-northwestward and passed near Sabtang, Batanes. The typhoon displayed a distinct circular shape in the cloud tops across the eyewall region, with a contracting eye that was obscured in the center. At 18:00 UTC, the JTWC reported that the system had peaked as a Category 4-equivalent super typhoon after Krathon attained 1-minute sustained winds of. Early on October 1, the JMA upgraded Krathon to a violent typhoon, estimating its peak intensity with a minimum central pressure of and 10-minute maximum sustained winds of.
As it moved into the northern area of the South China Sea, the cloud top temperatures of Krathon sharply decreased over the past six hours amid warm conditions. An eyewall replacement cycle became apparent in radar imagery, with the secondary eyewall almost completely encircling the inner eye. Once the eyewall replacement cycle was complete, Krathon began warming cloud tops and displayed a weakened cloud-filled eye feature that caused upwelling and a decrease in ocean heat content, and it was moving southwest of Taiwan, located between a subtropical ridge to the east and another ridge over southern China and northern Vietnam. The following day, satellite imagery revealed that the system remained symmetrical; however, warming cloud tops became exposed due to increasing vertical wind shear. On October 3 at 12:40 p.m. local time, Krathon made landfall near Siaogang District in Kaohsiung, Taiwan, with its spiral bands of deep convection gradually weakening as it moved north-northeastward into central Taiwan, near the western edge of the Central Mountain Range. This made Krathon the first storm to make landfall on Taiwan's densely populated western plains since Typhoon Thelma in 1977. After making landfall, the system rapidly slowed down and deteriorated, exhibiting minimal convective activity and ultimately weakening to a minimal tropical storm. The JTWC discontinued warnings on the system as it moved inland, where the rugged southeastern mountain ranges of Taiwan eroded much of the deep convection associated with the circulation center as it weakened to a tropical depression. The Central Weather Administration noted that Krathon was the first storm to hit Kaohsiung in October, and the first since Tropical Storm Trami in 2001 to weaken into a tropical depression over Taiwan. The JMA continued to monitor the system as it emerged into the South China Sea, where it remained nearly stationary between two mid-level subtropical highs before dissipating on the same day.

Preparations

Philippines

Shortly after PAGASA upgraded the storm, Tropical Cyclone Wind Signal No. 1 was issued for Batanes, Cagayan, Isabela, Apayao, Abra, Kalinga, the eastern and central portions of Mountain Province, the eastern portion of Ifugao, Ilocos Norte, the northern portion of Ilocos Sur, the northern portion of Aurora, northern and eastern Nueva Ecija, Pangasinan, La Union, Quirino, Benguet, and the Polillo Islands. As Krathon intensified into a severe tropical storm, Signal No. 2 was raised for the northeastern portion of Cagayan and the eastern portion of the Babuyan Islands. As the storm continued to intensify, PAGASA raised Signal No. 3 for the northeastern portion of the Babuyan Islands On September 29, various local government units announced the suspension of classes on September 30 because of inclement weather caused by the storm, while PAGASA raised Signal No. 4 in Batanes, Babuyan Island, and Calayan Island.
The Commission on Elections ordered an extension of voters' registration for the 2025 Philippine general election, which was due to end on September 30, in areas affected by the storm. Around 1,110 people were evacuated across Cagayan Valley. A red alert warning was declared in the municipalities of Calayan and Santa Ana in Cagayan. The Ambuklao, Binga and Magat Dams opened their gates in anticipation of an increase in water levels due to the storm. According to the NDRRMC, ten people were preemptively evacuated.