Typhoon Yutu
Typhoon Yutu, known in the Philippines as Typhoon Rosita, was an extremely powerful tropical cyclone that caused catastrophic destruction on the islands of Tinian and Saipan in the Northern Mariana Islands, and later impacted the Philippines. It is the strongest typhoon ever recorded to impact the Mariana Islands, and is tied as the second-strongest tropical cyclone to strike the United States and its unincorporated territories by both wind speed and barometric pressure. It also tied Typhoon Kong-rey as the most powerful tropical cyclone worldwide in 2018.
The twenty-sixth named storm and the twelfth typhoon of the 2018 Pacific typhoon season, Yutu originated as a tropical disturbance moving westward around the Marshall Islands on October 18. It became a tropical depression two days later, before strengthening further into a tropical storm on October 22, receiving the name Yutu from the Japan Meteorological Agency. Favorable conditions led to a period of rapid intensification as it moved west-northwestward, and by October 24, Yutu had achieved its peak intensity; the JMA estimated 10-minute maximum sustained winds of and a lowest central pressure of, while the Joint Typhoon Warning Center assessed 1-minute winds of. An eyewall replacement cycle ensued, weakening Yutu, before it made landfall over Tinian on October 25. Substantial outflow allowed the storm to re-strengthen, making it reach a secondary peak on October 26. As Yutu approached the Philippines the following day, PAGASA assigned it the local name Rosita as it reached less favorable conditions. The storm made a second landfall over Dinapigue, Isabela by October 29 before entering the South China Sea. It continued to weaken while turning northward, until it had dissipated by November 3.
An emergency was declared for the Northern Mariana Islands as Yutu approached the archipelago, while tropical cyclone warnings and watches were raised. Winds of and gusts of swept across Tinian and Saipan, causing devastating damage throughout the Northern Mariana Islands that amounted over, far exceeding that of Typhoon Soudelor in 2015. The storm destroyed up to 6,000 homes and toppled 962 power poles in Saipan and Tinian, leaving the islands without power for months. Health centers and airports in the two islands sustained serious damage. Two women were killed in Saipan and 121–133 people were injured. Yutu caused power outages to Rota and Guam, with damage to the latter island estimated at US$750,000. In response to the disaster, a major disaster declaration from U.S. President Donald Trump was signed; the Northern Mariana Islands received aid from organizations and local and federal governments.
Tropical Cyclone Wind Signals were issued throughout Luzon while the Philippines was still recovering from Typhoon Mangkhut, leading to pre-emptive evacuation of 32,519 people. Yutu brought rainfall of on the island, flooding low-lying areas. Yutu affected 567,691 people across the nation, displacing a majority of them after damaging 66,165 homes. The storm killed 32 people in the country, 21 of which died in Natonin from one of at least eleven landslides, and also injured two. Power outages occurred across Luzon, with most of it restored by October 31. Agricultural damage in the Philippines amounted to ₱2.904 billion. Elsewhere, a man in Hong Kong died while surfing in high waves as a typhoon signal was hoisted.
Meteorological history
Typhoon Yutu originated on October 18, 2018, from an area of atmospheric convection, or thunderstorms, near. Having an unorganized center with scattered convection, the tropical disturbance situated around warm waters of and low vertical wind shear, acquiring dual outflow channels aloft—all of which aided in development. Moving westward during October 20, the system received excellent equatorward outflow, while intense convection wrapped into its elongated center. By 18:00 UTC, the JMA reported that the disturbance had intensified into a tropical depression near the Marshall Islands. Eighteen hours later on October 21, the United States Joint Typhoon Warning Center designated the consolidating system 31W. A subtropical ridge to the southwest steered the storm west-northwestward, towards the Mariana Islands. Radial outflow was limited by a weak tropical upper tropospheric trough cell to the northwest, though the cell soon diminished the next day. At 00:00 UTC, both the JMA and JTWC classified the system a tropical storm, with the former assigning it the name Yutu.Yutu expanded in size, with the strongest convection to the east and south of the center; an intense rainband to the south later developed, marking the beginning of a period of explosive intensification. Deep convection bloomed, obscuring the center and significantly improving its structure with substantial poleward and radial outflow. At 18:00 UTC, the JMA upgraded Yutu to a severe tropical storm, and six hours later on October 23, both the JMA and JTWC classified the storm a typhoon. A pinhole eye began to develop, becoming apparent on satellite imagery, with banding features continuously tightening towards the center. A large area of intense thunderstorms persisted to the north of the center, as very favorable conditions fueled the typhoon. Over a region of high ocean heat content, the eye became well-defined and expanded to. Although it soon contracted to, by 00:00 UTC of October 24, Yutu was classified a super typhoon by the JTWC. The eye became wide, with extremely deep convective bands to the north and south of it. By 12:00 UTC, the JMA and JTWC reported that Yutu had attained its peak intensity; the former estimated 10-minute maximum sustained winds of and a barometric pressure of, and the latter estimated 1-minute winds of, making Yutu equivalent to a Category 5 hurricane on the Saffir–Simpson scale. Operationally, the JTWC estimated winds of —based on Dvorak estimates of T7.5, which utilized satellite appearance to determine intensity.
Between 14:00 UTC and 18:00 UTC, Yutu struck Tinian and the southern portion of Saipan at peak intensity, becoming the most powerful storm on record to impact the Northern Mariana Islands, surpassing Typhoon Soudelor in 2015. Additionally, the JTWC reported a lowest central pressure of at 18:00 UTC. After striking the Mariana Islands, cold cloud tops began to warm, signaling a weakening trend. Furthermore, microwave imagery revealed concentric eyewalls, indicating the onset of an eyewall replacement cycle. During the process, the eastern periphery of the eyewall thinned under the influence of dry air in the middle troposphere, as wind shear became moderate during October 25. The primary eyewall then eroded, as an anticyclone east of the storm obstructed outflow. The cycle was then completed, evident by a Special Sensor Microwave Imager/Sounder image. Yutu was more asymmetric, with its movement influenced by the subtropical ridge to the north and a large, weak mid-latitude shortwave trough associated with it. During October 26, the eye again became well-defined and expanded to, as low easterly wind shear and excellent outflow persisted despite the anticyclone. Convection near the center became symmetrical, cloud tops cooled, and the eye contracted and became cloud-filled. The eye then sharpened and became wide as convective bands wrapped very tightly into the intense center. By 18:00 UTC, the JMA and the JTWC reported that Yutu had attained its secondary peak intensity; the JMA estimated winds of and a minimum barometric pressure of, and the JTWC gave Yutu the same wind estimate as the previous peak.
Over the Philippine Sea, Yutu crossed the 135°E boundary of the Philippine Area of Responsibility at 00:00 UTC of October 27, receiving the local name Rosita from the Philippine Atmospheric, Geophysical and Astronomical Services Administration. Cloud tops reached as Yutu remained over warm waters, steering westward, though the eye became ragged. Yutu then briefly entered a region of high vertical wind shear, weakening the storm. The eye enlarged further to on October 28, though poleward outflow weakened. Intense thunderstorms eroded off the eastern edge of Yutu from dry air, which wrapped into the storm's circulation from the west, with cloud tops warming and the eye contracting; on this basis, the JTWC assessed that Yutu had weakened to below super typhoon strength at 12:00 UTC. Sea surface temperatures had also decreased in the cold wakes of previous Typhoons Mangkhut, Trami, and Kong-rey advected by the North Equatorial Current, contributing to the degrading of Yutu. While approaching Luzon, rainbands began to collapse, after outflow had reduced. Meanwhile, Yutu steered west-southwestward along the southern edge of the subtropical ridge. During October 29, the eye became ill-defined and cloud-filled, with most convection in the southern eyewall and limited in the northern part of it. Between 20:00 UTC and 21:00 UTC, Yutu made landfall over Dinapigue, Isabela, Philippines, with winds of estimated by PAGASA. The JTWC, however, reported that Yutu had made landfall at 19:50 UTC. The storm continued to rapidly decay tracking westward inland over the next day. Despite this, the system still remained organized as it began to emerge over the South China Sea, though it weakened into a severe tropical storm at 06:00 UTC according to the JMA.
Moving away from the Philippines, Yutu re-consolidated from improved banding over the northern flank, but weakened into a tropical storm at 18:00 UTC, according to the JTWC. Rainbands were limited to the north and south quadrants of the storm during October 31. At 06:00 UTC, the JMA downgraded Yutu to a tropical storm. Meanwhile, the storm left the PAR at 08:00 UTC. Exhibiting a partially exposed center, Yutu turned northwestward along the subtropical ridge. Regardless, the system stockpiled convection over its southern quadrant. Moreover, moderate wind shear was subdued by strong poleward outflow, making conditions favorable for intensification. By November 1, Yutu had briefly strengthened to near typhoon-force winds of, according to the JTWC. However, Yutu began experiencing moderate to high wind shear turning northward, limiting outflow and displacing deep convection to the northeast of the poorly defined center. By November 2, the JMA reported that Yutu had weakened into a tropical depression at 06:00 UTC; the JTWC followed suit in downgrading the system six hours later. After the storm had lost all of its convection from unfavorable wind shear while southeast of Hong Kong, the JTWC reported that Yutu had degenerated into a tropical disturbance at 18:00 UTC, whereas the JMA continued monitoring the system until it had dissipated on November 3 at 06:00 UTC.