Hurricane Hector (2018)
Hurricane Hector was a powerful and long-lived tropical cyclone that was the first to traverse all three North Pacific basins since Genevieve in 2014. The eighth named storm, fourth hurricane, and third major hurricane of the 2018 Pacific hurricane season, Hector originated from an area of low pressure that formed a couple hundred miles west-southwest of Mexico on July 28. Amid favorable weather conditions, a tropical depression formed a few days later on July 31. The depression continued strengthening and became Tropical Storm Hector on the next day. Hector became a hurricane on August 2, and rapidly intensified into a strong Category 2 hurricane later in the day. After weakening while undergoing an eyewall replacement cycle, Hector quickly strengthened into a Category 4 hurricane late on August 5. Over the next week, Hector fluctuated in intensity multiple times due to eyewall replacement cycles and shifting wind shear. Hector achieved its peak intensity on August 6, as a high-end Category 4 hurricane with winds of 155 mph. On the following day, the hurricane bypassed Hawaii approximately 200 mi to the south. Increasing wind shear resulted in steady weakening of the storm, beginning on August 11. At that time, Hector accumulated the longest continuous stretch of time as a major hurricane in the northeastern Pacific since reliable records began. Eroding convection and dissipation of its eye marked its degradation to a tropical storm on August 13. The storm subsequently traversed the International Dateline that day. Hector later weakened into a tropical depression on August 15, before dissipating late on August 16.
Hector prompted several islands in the Papahānaumokuākea Marine National Monument to issue tropical storm watches after the close pass by in Hawaii that warranted the issuance of a tropical storm warning for Hawaii County. Despite Hector having passed a couple hundred miles to the south of Hawaii, it still brought numerous adverse weather effects to Hawaii County and the surrounding islands.
Meteorological history
On July 26, the National Hurricane Center started watching an area of low pressure was forecast to form a couple hundred miles south-southwest of Mexico in a few days. Two days later, this forecast verified as a broad area of low pressure formed several hundred miles south-southeast of Acapulco. The system gradually developed over the next few days, which prompted the NHC to declare the system a tropical depression at 12:00 UTC on July 31. Initially, Hector was expected to travel in a northwesterly direction before shifting to a more westerly direction after the subtropical ridge expanded to the south. At midnight UTC on August 1, the depression intensified to a tropical storm, receiving the name Hector; based on an increase in curved banding features and a Dvorak intensity estimation. Despite a projected increase in wind shear, steady strengthening to a hurricane was expected.For the next several days, Hector generally traveled west without gaining much latitude while steadily intensifying, with microwave imagery revealing the emergence of a mid-level eye, an indication that rapid intensification was likely to take place. By 18:00 UTC on August 2, Hector had rapidly intensified to a Category 2 hurricane on the Saffir–Simpson scale with maximum sustained winds of 105 mph and a minimum barometric pressure of. At this time, Hector was a small hurricane, with hurricane force winds extending only 15 miles from the center. Because of an increase in northerly wind shear and the beginning of an eyewall replacement cycle, Hector weakened to a Category 1 hurricane on the afternoon of August 3.
After completing the eyewall replacement cycle, Hector quickly strengthened into a Category 3 hurricane on August 4. Hector then gradually strengthened throughout the day. Shortly before 15:00 UTC on that day, microwave data indicated that a second eyewall replacement cycle was occurring. Hector reached Category 4 status at 18:00 UTC, as the eye became more pronounced, and Hector acquired some characteristics of an annular hurricane. Despite gradual weakening having been forecast, Hector subsequently began to rapidly strengthen. Shortly after 06:00 UTC, Hector entered the Central Pacific Hurricane Center's warning zone after crossing the 140°W.
on August 7
Late on August 6, Hector intensified further and peaked with maximum sustained winds of 155 mph. Later on the same day, Hector weakened, due to interactions with drier air. As the weakening trend progressed, Hector's wind field began to expand. On August 8, Hector weakened to a Category 3 hurricane again. At 21:00 UTC, Hector made its closest approach to Hawaii, approximately south of Hilo with winds of. At the same time, microwave data indicated Hector had begun a third eyewall replacement cycle, which finished early on August 9, as satellite presentation of the hurricane immensely improved, with the eye warming. Unlike Hector's previous eyewall replacements, Hector maintained its intensity at that time. Early on August 10, Hector regained Category 4 status, and at 18:00 UTC on the same day, Hector reached its secondary peak intensity with winds of 140 mph as it began to turn west-northwestward, due to a subtropical ridge that formed to the north. On August 11, Hector began another weakening trend as increasing wind shear began to have an impact on the system, though by this time, the hurricane set the record for the longest consecutive duration as a major hurricane in the northeastern Pacific. Late on August 11, Hector weakened below major hurricane strength, a status it had held for nearly eight days, because of increasing wind shear while the storm took a turn to the northwest, due to the influence of the subtropical ridge.
Hector quickly weakened to Category 1 status on August 12, due to strong south-southwesterly shear. On August 13, Hector weakened further to a tropical storm. Later on the same day, Hector crossed over the International Date Line, exiting the Central Pacific basin and entering the West Pacific basin; the CPHC thus ceased issuing advisories on Hector and passed that responsibility to the Japan Meteorological Agency and the Joint Typhoon Warning Center. Hector continued weakening on the next day, amid continued southeasterly wind shear, lower oceanic heat content, and nearby dry air. The system became increasingly disorganized, and the JTWC issued its last advisory on Hector on August 15, as the system weakened into a subtropical depression. Afterward, Hector turned northward around the edge of the aforementioned subtropical ridge, while continuing to weaken. The JMA last noted Hector late on August 16, as the storm dissipated.
Preparations and impact
Although forecasts depicted Hector remaining south of Hawaii, concerns were raised over the safety of residents displaced by the ongoing eruption of Kīlauea. Many remained in temporary tent structures that could not withstand a hurricane; however, plans were made to relocate people to sturdier structures. A tropical storm watch was issued for Hawaii County on August 6; this was upgraded to a tropical storm warning early on August 8. The tropical storm warning was discontinued later that day as Hector stayed far offshore.On August 5, the ports of Hilo and Kawaihae were closed to inbound traffic as gale-force winds were expected to occur within the next 24 hours. On August 7, the acting mayor of Hawaii County, Wil Okabe, declared a state of emergency as Hector was approaching from the east. The next day, all absentee walk-in voting sites as well as Whittington, Punaluu, and Milolii Beach Parks in Hawaii County were closed as Hector passed by to the south. On August 8, high surf was reported along the south facing shores on the Big Island. In all, at least 90 people necessitated rescue on Oahu due to dangerous swells generated by the cyclone. All Hawaiian ports resumed normal operations on August 10.
On August 9–10, Johnston Atoll briefly received a tropical storm watch as Hector approached the atoll, On August 11, a tropical storm watch was issued for portions of the Papahānaumokuākea Marine National Monument from Lisianski Island to Pearl and Hermes Atoll, and on the next day, was issued for Kure Atoll and Midway Atoll and the waters between Midway Atoll and Pearl and Hermes Atoll. The watches were gradually cancelled as Hector weakened and moved away from the islands, with none remaining by August 13.