of Hilo, Hawaii. The disturbance entered the Central Pacific Basin on September 26 as a mixture of low-level clouds and larger cumulus clouds. A subtropical ridge located north of the Hawaiian Islands caused the system to track westward over the next few days. A surface low formed by 12:00 UTC on September 27 as the system was located 805 mi (1,295 km) southeast of Hilo. The system became Tropical Depression One-C around 12:00 UTC on September 29 while it was around 690 mi (1,110 km) south of Honolulu, Hawaii. Convection or thunderstorm activity formed near the system's low-level circulation center, and a banding featuresignificantly elongated, curved bands of rain clouds became established over the southern and eastern portions of the depression. Six hours later, the system strengthened into a tropical storm, receiving the name Walaka from the Central Pacific Hurricane Center (CPHC). The nascent tropical storm was located in an environment of warm sea surface temperatures, low vertical wind shear, and humid air. After forming, the cyclone's banding features degraded, although its convection persisted. Meanwhile, the ridge continued to steer Walaka westward. Around this time, Walaka began a stint of rapid intensification. Convection became more abundant around the storm's low-level center during the morning of September 30. Walaka's cloud tops cooled; the tropical cyclone intensified into a hurricane by 18:00 UTC. A cloud-filled eye emerged on visible satellite imagery by early October 1 as Walaka continued to strengthen. Walaka became a Category 3 major hurricane around 12:00 UTC on October 1, the fourth storm to do so in the Central Pacific in 2018. At that time, the hurricane possessed a prominent eye surrounded by a sizeable ring of cold clouds. Walaka turned towards the west-northwest as it moved around the southwestern edge of the ridge. Walaka peaked as a Category 5 hurricane, with maximum sustained winds of 160 mph (260 km/h) and a minimum central pressure of , at 00:00 UTC on October 2. Walaka's peak intensity made it the second Category 5 hurricane of the 2018 Pacific hurricane season. Around that time, the cyclone had a clear, 23-mile (37 km) wide eye surrounded by cool cloud tops. Meanwhile, microwave imagery and ASCAT data showed the formation of concentric eyewalls, signaling that an eyewall replacement cycle had commenced. A strengthening upper-level low located north of Walaka was causing the hurricane to begin a more northward track. Walaka maintained its peak