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 in late October 2018. It was the strongest typhoon ever recorded to impact the Mariana Islands before Typhoon Bavi in 2026, 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, behind Bavi. 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 depression moving westward around the Marshall Islands on October 20, becoming a tropical storm by October 22 and receiving its name 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 as it made landfall over Tinian on October 25. An eyewall replacement cycle ensued, before the storm re-strengthened as it approached Luzon, which then entered marginal conditions; it made a second landfall over Dinapigue, Isabela by October 29 before entering the South China Sea, where it weakened 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 (US$55.160 million). Elsewhere, a man in Hong Kong died while surfing in high waves as a typhoon signal was hoisted.
Meteorological history
On October 18, 2018, an unorganized tropical disturbance formed near , attaining scattered convection, or thunderstorms, over conducive conditions for tropical cyclogenesis of low vertical wind shear and warm sea surface temperatures, in addition to dual outflow channels aloft. Moving westward during October 20, deepening convection wrapped into the elongated low-level circulation. By 18:00 UTC, the Japan Meteorological Agency (JMA) ranked the storm system a tropical depression near the Marshall Islands. Eighteen hours later on October 21, the United States Joint Typhoon Warning Center (JTWC) designated it 31W. A subtropical ridge to the southwest steered the storm west-northwestward, towards the Mariana Islands. Excellent outflow around the storm was limited by a weak tropical upper tropospheric trough (TUTT) 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 naming it Yutu. The strongest convective activity occurred to the east and south as Yutu expanded in size; an intense rainband to the south later developed, marking the beginning of a period of explosive intensification. Convection bloomed over the center, significantly improving its structure. 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 was later apparent on satellite imagery. Amid very favorable conditions, with the addition of high ocean heat content, the eye became well-defined. By 00:00 UTC of October 24, Yutu was classified a super typhoon by the JTWC. Yutu presented extremely deep convective bands to the north and south, and 12 hours later, had reached its peak intensity; the JMA estimated 10-minute maximum sustained winds of and a barometric pressure of . The JTWC assessed 1-minute winds of , revised from preliminary estimates of based on Dvorak estimates of T7.5—which utilized satellite appearance to determine intensity. Between 14:00 UTC and 18:00 UTC (00:00 ChST and 04:00 ChST of October 25), 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 at the time, surpassing Typhoon Soudelor in 2015. Additionally, the JTWC reported a lowest central pressure of at 18:00 UTC. After striking the Mariana Islands, an eyewall replacement cycle occurred, halting any strengthening. Mid-level dry air thinned the east side of the eyewall, with an anticyclone to the east obstructing outflow during October 25. After completing the cycle on October 26, the eye grew to and became well-defined once again, as low easterly wind shear and excellent outflow persevered despite the anticyclone. Strengthening resumed albeit with less outflow to the east, and by 18:00 UTC, the JMA and the JTWC reported that Yutu had reached a second peak; 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 (PAR) at 00:00 UTC of October 27, receiving the local name Rosita from PAGASA. Steering westward towards Luzon, Yutu remained over warm waters, though the eye turned ragged. Yutu briefly entered a region of high vertical wind shear. On October 28, convection eroded off the eastern edge of Yutu from westerly dry air, as cloud tops warmed and the eye contracted; on this basis, the JTWC assessed that Yutu had weakened 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. After outflow had reduced, rainbands began collapsing while Yutu drifted west-southwestward. On October 29, the eye turned cloud-filled, constricting most convection to the southern eyewall. 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. Over the next day inland, the storm continued to rapidly decay; despite this, the system 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 northern banding, but weakened into a tropical storm at 18:00 UTC, according to the JTWC. At 06:00 UTC of October 31, 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, stockpiling convection over its southern quadrant. Moreover, moderate wind shear was subdued by strong poleward outflow, making conditions favorable for intensification again. 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 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.
Preparations Mariana Islands
On October 20, the National Weather Service (NWS) office in Tiyan, Guam released a Special Weather Statement on the pre-Yutu disturbance after a Tropical Cyclone Formation Alert from the JTWC was issued, stating that it could impact the Mariana Islands by midweek. Two days later, the NWS instated a tropical storm watch for Rota and a typhoon watch on Saipan and Tinian. As Tropical Storm Yutu continued towards the archipelago, tropical storm watches were added on Guam, Alamagan, Pagan, and Agrihan. With forecasts stating that Yutu would become a typhoon, the watches for Saipan and Tinian were upgraded to warnings on October 23; all tropical storm watches were upgraded to warnings later that day, and the typhoon watch for Rota was upgraded to a warning also. After Yutu had made landfall, all warnings and watches were canceled on October 25 as it moved away. In the month prior to Yutu, Typhoon Mangkhut struck the Mariana Islands, prompting emergency officials to stockpile supplies. With relief supplies largely unused, storage facilities on Guam had 220,000 liters of water and 260,000 meals readily available.
Condition of Readiness (COR) 2 was hoisted in Rota, Saipan, and Tinian on October 23, before it was upgraded to COR 1 the next day after Yutu had become a super typhoon. Governor Ralph Torres ordered all government offices to shut down in preparation of Yutu. Additionally, Northern Marianas College campuses were closed on October 23. The Chief Judge of the District Court, Ramona Villagomez Manglona, closed the federal court. Attorney General Edward Manibusan warned retailers against price gouging. Public schools canceled classes across the three main islands. Seven were used as shelter to accommodate 326 people; some of them were filled quickly. Hundreds of cars lined up at gas stations. U.S. President Donald Trump declared an emergency for the Northern Islands on October 24, which allowed the Federal Emergency Management Agency (FEMA) to deploy personnel to both Tinian and Saipan ahead of the storm. The Department of Fire and Emergency Medical Services in Saipan deployed a team in preparations. All flights in the Northern Marianas were canceled, though the Saipan International Airport remained open. The Commonwealth Utilities Corp. shut its water distribution system to conserve water tanks. Several businesses were closed, hotel constructions were suspended, and banks, restaurants, and other shops were boarded. Imperial Pacific suspended its casino. The United States Postal Service closed its offices in Saipan and Rota. United States Coast Guard ports were closed across Saipan, Tinian, Rota, and also Guam.