Tropical Storm Fabio (2006)

Tropical Storm Fabio was a short-lived tropical cyclone that contributed to a period of heavy rainfall in Hawaii. The fourth named storm of the 2006 Pacific hurricane season, Fabio developed from a tropical wave on July 31 off the southwest coast of Mexico. It maintained a steady westward track throughout its duration, attaining peak winds of 50 mph (85 km/h) before weakening due to wind shear and dry air. The remnants of Fabio passed near Hawaii on August 7 after dissipating the previous day, though no significant damage or deaths were reported. However, rainfall from the system caused flash flooding and left 24 hikers stranded and in need of rescue by helicopter.

Meteorological history
A tropical wave moved off the west coast of Africa on July 15. It tracked westward across the Atlantic Ocean and Caribbean Sea, generating limited thunderstorms along its path. The wave crossed Central America into the eastern Pacific Ocean around July 25, and three days later developed a weak low pressure area about 515 miles (835 km) southwest of Manzanillo, Colima. The system developed an area of convection, which gradually organized over the next few days. By July 30, the National Hurricane Center (NHC) began noting the potential for tropical cyclogenesis. Late on July 31, the system acquired enough persistent deep convection to be designated a tropical depression, while located about 980 miles southwest of the southern tip of the Baja California peninsula.

Upon becoming a tropical cyclone, the depression was moving westward, influenced by a mid-level ridge to its north. Within six hours of developing, it attained tropical storm status and was named Fabio by the NHC. Located within an environment only marginally favorable for intensification, Fabio was forecast to strengthen only slightly. The convection organized into curved rainbands on August 1, and with its increased organization, the storm attained peak winds of 50 mph (85 km/h). Tropical Storm Fabio maintained its peak intensity for about 24 hours, during which its convection became shifted to the north of the circulation due to increased wind shear. By August 2, continued shear and increased dry air caused the convection to diminish greatly, before thunderstorms later increased to the west of the center. Later that day, the convection again decreased, leaving the circulation exposed from the thunderstorm activity; by that point, Fabio had weakened to tropical depression status. After the cyclone was unable to regenerate any significant convection for about 24 hours, the NHC declared Fabio a remnant low early on August 4. The low continued westward, degenerating into an open trough on August 6 about 450 mi (725 km) southeast of Hilo, Hawaii. The remnants moved across much of Hawaii on August 7, bringing locally heavy rainfall.

Preparations and impact
As a tropical cyclone, Fabio did not affect land. However, moisture from the remnant trough of low pressure combined with an upper-level low to produce thunderstorms and heavy rainfall across much of Hawaii. In Glenwood on the island of Hawaii, the system produced 2.89 inches (73 mm) of rainfall in one day; this was the highest daily rainfall total for the month on the island. The heaviest rainfall associated with the system fell on Mount Waiʻaleʻale on the island of Kauai, where 15.08 inches (383 mm) of rainfall fell in a 24 hour period; this 24 hour total alone was greater than all other monthly rainfall totals in the state. The rainfall led to flooding along the Hanalei River, which forced the closure of the Kuhio Highway when a bridge was flooded. On Oahu, the rainfall caused ponding on roadways and flooding along streams. One flooded stream stranded 24 hikers along a trail, who required rescue by helicopter.