Hurricane Hector

Category 4 major hurricane (SSHWS/NWS)
Hurricane Hector at peak intensity southeast of Hawaii on August 6
Formed	July 31, 2018
Dissipated	August 16, 2018
Highest winds	1-minute sustained: 155 mph (250 km/h)
Lowest pressure	936 mbar ( hPa); 27.64 inHg
Fatalities	None
Damage	Minimal
Areas affected	Hawaii, Johnston Atoll
Part of the 2018 Pacific hurricane and typhoon seasons

Origins, development, and initial peak

Hurricane Hector's origins can be traced to a low-latitude disturbance that was located north of French Guiana and Suriname around July 22. The disturbance's path prior to that time is uncertain because convective activity was subdued across the tropical Atlantic due to the presence of dry Saharan air. Additionally, the Intertropical Convergence Zone dipped southward and exhibited no fluctuations; a combination of both events made it impossible to trace the disturbance to a particular tropical wave. Hector's precursor began producing convection while traveling westward over South America, entering the Eastern Pacific basin by July 25. A low-pressure trough formed on the next day south of Central America and southern Mexico. ^[1] The National Hurricane Center (NHC) first mentioned the possibility of tropical development on July 26. ^[2] Located within a favorable environment fueled by a kelvin wave and the Madden–Julian oscillation, ^[1] the disturbance gradually became more organized over the next five days as it continued generally westward. ^[3] The system strengthened into a tropical depression around 12:00 UTC on July 31 while about 805 mi (1,295 km) south-southwest of the southern tip of the Baja California Peninsula. ^[1] At that time, the system was travelling west-northwest under the influence of a deep-layer ridge to its north. Initially, the depression was irregularly shaped and its circulation elongated, ^[4] however, it steadily improved in organization over the next 12 hours, becoming Tropical Storm Hector at 00:00 UTC on August 1. ^{[1] [5]}

After strengthening into a tropical storm, increasing easterly wind shear caused Hector to remain disorganized for several hours, with most of its convection displaced to the south and west. ^[6] Warm sea surface temperatures of 81–82 °F (27–28 °C) allowed Hector to begin a 30-hour period of rapid intensification at 12:00 UTC. ^[1] Around that time, the low- and mid-level centers were becoming more aligned and curved banding features were increasing. The system also turned westward as the aforementioned ridge built to the north of Hector. ^{[7] [8]} Over the next several hours, Hector significantly improved in organization, with its low-level center becoming markedly embedded within the deep convection and the development of a mid-level eye. ^[9] Hector intensified into a Category 1 hurricane on the Saffir-Simpson scale around 12:00 UTC, developing a small eye on satellite imagery. ^{[1] [10]} Six hours later, the storm reached its initial peak intensity as a Category 2 hurricane with maximum sustained winds of 105 mph (165 km/h) and a minimum central pressure of 975 mbar (28.79 inHg). ^[1] Shortly after, Hector began weakening, with its eye becoming cloud filled and the northern eyewall eroding due to northerly shear. ^{[11] [1]} Hector's structure continued to degrade over the next several hours with the eye becoming nearly indistinguishable from its surroundings and the formation of a secondary concentric eyewall structure. ^[12] The storm bottomed out as a Category 1 hurricane at approximately 12:00 UTC on August 3 as it continued to travel due west. ^[1]

Strengthening and peak intensity

Soon after, Hector began to strengthen as it traversed an area of slightly cooler sea temperatures, low wind shear, and elevated mid-level moisture. The storm's eye cleared out on satellite imagery as convection intensified in the eyewall. ^[13] Hector became a Category 3 major hurricane around 00:00 UTC on August 4, while located approximately 1,680 miles (2,705 km) west-southwest of the southern tip of Baja California. ^[1] Later in the day, the system began to undergo an eyewall replacement cycle. At the same time, the storm continued to track westward. ^[14] Six hours later, around 18:00 UTC, the eyewall cycle had completed, with only one eyewall remaining. At that time, the cyclone was also beginning to acquire some annular characteristics. ^[15] The hurricane's structure began to decay on August 5, with the eye becoming less distinct by 12:00 UTC. Meanwhile, microwave imagery showed two concentric eyewalls, indicating that Hector was entering a second eyewall replacement cycle. ^[16] Hector became a Category 4 hurricane at 18:00 UTC after completing the eyewall cycle. ^[1] The hurricane exhibited a symmetric central dense overcast with few banding features elsewhere, a characteristic of an annular tropical cyclone. ^[17]

Hector began to move slightly north of west due to a weakness in a subtropical ridge located to the northeast of the Hawaiian Islands. The hurricane crossed the 140th meridian west shortly after 06:00 UTC on August 6, entering the Central Pacific Hurricane Center's (CPHC) area of responsibility. ^[1] At that time, Hector possessed a distinct eye surrounded by −94 to −112 °F (−70 to −80 °C) clouds. ^[18] About six hours later, a 53rd Weather Reconnaissance Squadron plane recorded a stepped frequency microwave radiometer (SFMR) wind speed of 158 mph (254 km/h) as it surveyed the cyclone. Hector reached its peak intensity with maximum sustained winds of 155 mph (250 km/h) and a minimum central pressure of 936 mbar (27.64 inHg) around 18:00 UTC. ^[1] The storm turned towards the west-northwest shortly after as the ridge continued to weaken. ^[19] The hurricane maintained peak intensity for about six hours before beginning to weaken as it entered an area of mid-level dry air. Despite slightly degradating in structure, the Hector still maintained a 12 mi (19 km) wide eye. ^[20]

Passage south of Hawaii and secondary peak

Weakening and demise

See also

• Other tropical cyclones with the same name
• List of Category 4 Pacific hurricanes
• List of Hawaii hurricanes
• Hurricane Dora (1999) – another hurricane that traversed all three North Pacific basins
• Hurricane Ioke – a storm that set similar longevity records
• Hurricane Lane (2018) – Category 5 hurricane that became Hawaii's wettest tropical cyclone on record

References

External links

Wikimedia Commons has media related to Hurricane Noah/Sandbox8.

• The National Hurricane Center's advisory archive on Hurricane Hector
• The Central Pacific Hurricane Center's advisory archive on Hurricane Hector