Oho (2015)

A tropical disturbance in a monsoon trough south of Hawaii developed into Tropical Depression Seven-C at 0600 UTC on 3 October 2015 about 520 nautical miles south of Honolulu. The system became Tropical Storm Oho later that day and followed a generally northeastward path while accelerating. Oho strengthened steadily through 6–7 October, reached peak intensity on 7 October, and then moved over much cooler waters and into stronger wind shear. It lost tropical characteristics and became a post-tropical/extratropical low by 1200 UTC 8 October, then continued northeastward, producing an intense extratropical low that moved into southwest Alaska near Icy Bay on 10 October before dissipating over western Canada later that day.

Oho did not make any landfalls while it was a tropical cyclone. Its center remained well offshore of the Hawaiian Islands and there were no coastal watches or warnings required during the tropical phase. The remnant extratropical low later moved ashore in southwest Alaska near Icy Bay on 10 October.

The storm’s maximum sustained winds reached 95 knots (about 110 mph) and its minimum central pressure fell to 957 mb at 1200 UTC on 7 October, making Oho a Category 2 hurricane at peak intensity on the Saffir–Simpson scale.

There were no reports of storm surge or measured tropical-storm-force or greater surface winds associated with Oho while it was tropical, and the report lists no rainfall totals or surge measurements tied to the hurricane affecting populated locations. After Oho became extratropical and intensified, it produced strong winds over the North Pacific, but the official report does not attribute specific surge heights or rainfall totals to named cities or counties.

There were no reported deaths, injuries, or damage attributed to Hurricane Oho. The storm was notable for having formed from a monsoon-trough disturbance—an uncommon genesis mechanism for the Central North Pacific—and for undergoing aircraft-observed intensification to hurricane strength. Forecasts of Oho’s genesis were successfully raised in advance, but track forecasts had larger-than-average errors early in its life because the low formed within the monsoon trough and initial center positions were uncertain; intensity forecasts performed reasonably well at longer lead times.