Typhoon Wutip (2019)

Typhoon Wutip, known in the Philippines as Tropical Depression Betty, was the most powerful February typhoon on record, surpassing Typhoon Higos of 2015. The third tropical cyclone, second tropical storm, and the first typhoon of the 2019 Pacific typhoon season, Wutip originated from a low-pressure area on February 16, 2019, that generally tracked westward, passing just south of the Federated States of Micronesia (FSM), before organizing into a tropical depression on February 18. The depression was later classified a tropical storm a day later, attaining the name ''Wutip'' from the Japan Meteorological Agency. The storm gradually intensified as it turned northwest, before it underwent rapid intensification on February 23, while passing to the southwest of Guam, and reached its first peak intensity. With winds of 270 km/h (165 mph) estimated by the Joint Typhoon Warning Center, Wutip became the first Category 5-equivalent super typhoon on record in the month of February. Wutip underwent an eyewall replacement cycle shortly afterward and weakened. The storm finished its cycle on February 24, rapidly intensifying once again. Wutip reached a secondary peak intensity the following day, again attaining Category 5-equivalent winds. Thereafter, Wutip rapidly weakened for the rest of its lifespan from strong vertical wind shear, before dissipating over the Philippine Sea on March 2.

As tropical cyclone watches and warnings were issued and citizens sought shelter, Typhoon Wutip crossed the FSM and inflicted significant damage towards its agriculture and infrastructure, contaminating water sources across the affected islands with its floods and leaving 11,575 people in need of food. Later on, Wutip induced power outages in Guam and caused damage that added to the total of over $3.3 million (2019 USD). The Northern Mariana Islands received minor impact, and there were no casualties reported in any of the affected areas nonetheless. In response to the effects, both the FSM and Guam received aid from international governments and organizations.

The name "Wutip" (蝴蝶) proposed by Macau, meaning "butterfly" in Cantonese.

Meteorological history

Around mid-February 2019, a large mass of cumulonimbus clouds accumulated near the Marshall Islands. Initially disorganized, the slow-moving cluster consolidated into a more cohesive system. On February 16, the Japan Meteorological Agency (JMA) detected the system as a low-pressure area shifting westward. While southeast of Kosrae, vigorous convergence of trade winds north of the tropical disturbance spawned sporadic convection, or thunderstorms. The convection broadened over the system's large but weak circulation, as the disturbance situated over an area of low vertical wind shear and warm sea surface temperatures of , conditions which are conducive for tropical cyclogenesis. After more organizing, the JMA identified the system as a tropical depression on February 18, shortly before the Joint Typhoon Warning Center (JTWC) assigned it the numeral identifier ''02W'' the next day, when the storm had improved its convective banding around the defined circulation. As the storm developed from high ocean heat content (OHC) and outflow, the JMA and JTWC simultaneously ranked the newborn cyclone a tropical storm at 18:00 UTC, with the former giving it the name ''Wutip''.

On February 20, Wutip evolved into a severe tropical storm after attaining 10-minute sustained winds of , before strengthening into a typhoon by 18:00 UTC, according to the JMA, as a central dense overcast began to surface. With Wutip moving west-northwestward alongside a subtropical ridge to the north, improvement in organization became apparent with an eye formation detected on microwave imagery; on this basis, the JTWC upgraded Wutip to a typhoon early on February 21. The storm continued to significantly intensify over warm waters as rainbands tightened towards the deepened core. Its motion also mitigated the effects of wind shear, and additionally, a ragged eye emerged on satellite imagery. The very compact system then steered in a general northwestward direction, with the eye occasionally appearing throughout February 22. Despite a decrease in sea surface temperatures, low wind shear combined with an excellent poleward outflow channel commenced a period of rapid intensification on February 23. While southwest of Guam, Wutip presented a compact eyewall, and achieved its initial peak intensity at 12:00 UTC; the JMA estimated 10-minute sustained winds of and the lowest barometric pressure of around that time. The JTWC operationally estimated 1-minute sustained winds of , re-classifying Wutip as a super typhoon; however, post-season analysis determined that it had attained winds of 270 km/h (165 mph) two hours prior—making Wutip equivalent to a Category 5 hurricane on the Saffir–Simpson hurricane wind scale.

A moat—a clear ring outside the eyewall—separated the inner core from deep banding features, indicating the onset of an eyewall replacement cycle. During the process, the western portion eroded off the well-defined but warming eyewall as the eye cooled down, signaling a weakening trend. Development was further hampered by dry air entrainment and the storm's entrance to an environment of low OHC; conditions in the upper troposphere however, remained favorable. The moat separating the primary and secondary eyewall then became ill-defined. Upon completion the next day, the eyewall thickened, and its associated convection was replenished and reorganized, becoming well-defined and annular, resuming a trend of rapid intensification. Wutip again became a Category 5-equivalent super typhoon in 06:00 UTC of February 25, reaching a secondary peak intensity with 10-minute winds of and atmospheric pressure of assessed by the JMA, and 1-minute winds of assessed by the JTWC. Although maintaining deep convective rings, Wutip did not hold this intensity for long, and by the following day, weakened to below super typhoon strength. Cloud tops warmed up as the eye became cloud-filled. Following a significant increase in vertical wind shear, Wutip's structure began to rapidly deteriorate, no longer exhibiting an eye.

The storm decelerated from a neutral point as it entered the southern edge of the westerlies, meeting higher levels of unfavorable wind shear. An upper-level trough situated to the west of the storm also reinforced wind shear, further disrupting convection, despite the robust outflow. By 12:00 UTC of February 27, Wutip had weakened back into a severe tropical storm. Convection later decreased significantly, prompting the JTWC to downgrade Wutip to tropical storm status. As Wutip turned west-northwestward, deep convection detached from the storm and dissipated, preventing additional development. By February 28, wind shear had completely exposed the well-organized circulation. The JMA downgraded Wutip to a tropical storm at 00:00 UTC, before downgrading it further to a tropical depression six hours later, though the JTWC had already assessed Wutip as a tropical depression beforehand. On the same day, Wutip crossed the 135° E boundary of the Philippine Area of Responsibility, receiving the local name ''Betty'' from the PAGASA—the national weather agency for the Philippines. The JTWC discontinued advisories on Wutip, whereas the JMA continued monitoring the depression until it had dissipated near east of the Philippines on March 2.

Records

Wutip was the most powerful typhoon in the month of February on record, surpassing Typhoon Higos of 2015, while also being the longest-lasting typhoon of that month as well. In addition, Wutip is the first and only tropical cyclone in the Northern Hemisphere with Category 5-equivalent winds during the month. Only seven Category 4- or Category 5-equivalent typhoons were recorded in the months of January and February since the late 1940s, including three other storms in February that attained Category 4 strength.

Preparations and impact

Federated States of Micronesia

Tropical storm watches and warnings were issued for the states of Chuuk, Pohnpei, and Yap of the Federated States of Micronesia by the National Weather Service (NWS) office in Tiyan, Guam, as Tropical Depression 02W approached the island nation on February 19; the tropical storm warning for Faraulep in Yap was later canceled. The advisories were upgraded to typhoon watches and warnings after the tropical depression had intensified into Tropical Storm Wutip on February 20, with forecasts stating that Wutip would soon strengthen into a typhoon. A Special Weather Statement was also released, advising residents to monitor the situation and take note of instructions. While schools, community halls, and gymnasiums were all used as shelter, some shelters did not provide food and water or proper restrooms.

Wutip passed over Chuuk, Pohnpei and Yap States with winds of more than —equivalent to a Category 2 hurricane—from February 19 to 22, and damaged or destroyed approximately 160 houses and displaced 165 people in Chuuk and Yap. In Pohnpei State, primary and secondary power lines were damaged. Besides having fallen trees, the main island of Pohnpei was entirely left without power before having it restored. The command post of Chuuk State was activated on February 20–21 under an issued executive order, as falling trees, flooding, and damage towards homes were being reported on the 21st. Displaced people were moved to typhoon shelters and also to families residing more inland, away from the shorelines. In Pattiw, 54 homes were destroyed and at least 69 were damaged. Schools were closed down as an effect of major damage as displaced families sheltered in them. In some of the affected islands of Yap, schools also sustained damage. Satellite imagery analysis after the storm revealed extensive damage to vegetation and limited damage to structures of the Northwest Islands.

The Northwest Islands and Mortlock Islands had over 90% of their crops damaged, likewise to Nukuoro of Pohnpei State; the main crop, taro, rottened and became no longer edible, though some of it was salvaged. Water sources for the outer islands of Houk, Puluwat, Tamatam and Pulap, along with the Mortlock Islands, were rendered undrinkable, contaminated by saltwater from the flooding. In Houk, sea water flooding killed vegetation, including taro, breadfruit and coconut—the main diet for the inhabitants besides fish. Wutip flooded a taro plantation in Oneop and downed breadfruit and banana trees with its winds. Structures there were unroofed and one structure had collapsed. Across the state of Yap, infrastructure, including dispensaries, and crops were damaged. Residents of Satawal, Lamotrek, Elato, Faraulep, and Piig necessitated water assistance, as their drinking sources were soon to be exhausted. Despite no casualties, Wutip ruined many crops with the saltwater floods it produced and, with the water sources contaminated, induced a high possibility of disease outbreaks in the affected areas. Overall, Wutip caused heavy preliminary damage in infrastructure and agriculture that cost at least $2 million.

Guam

The NWS announced a tropical storm watch for Guam on February 21. Guam was still reeling from Typhoon Mangkhut in the previous year as hundreds fled to emergency shelters; over 430 children and adults sought refuge at five different emergency shelters. Public schools were closed in preparation of Wutip on February 22. The same day, Cope North, an annual military exercise that takes place around Guam, was paused "as a precautionary measure due to hazardous and potentially damaging winds," according to the Pacific Air Forces. The NWS also upgraded the watch to a tropical storm warning on that day. A team of 18 from the Federal Emergency Management Agency (FEMA) assisted Guam with emergencies. Civil defense officials warned Guam residents that winds between and rainfall up to were expected, and advised them to stay indoors until the storm had passed. Lieutenant Governor Josh Tenorio put Guam and the military bases under Condition of Readiness (COR) 2, before upgrading it to COR 1. About 25 flights to and from Guam were canceled, leading to the loss of 4,993 seats.

As Wutip's rainbands began affecting the island, a heavy outer rainband remained largely in place over the southern side for several hours, and exhibited the meteorology phenomena training. Wutip was the first typhoon to affect Guam in the month of February since Typhoon Irma in 1953. On February 23, Antonio B. Won Pat International Airport recorded of rain from the storm, resulting in a flash flood warning being announced, while also setting a record for that date. The Guam Power Authority

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