Guillermo (2009)

Hurricane Guillermo formed from a tropical wave in the eastern Pacific and became a tropical depression on August 12, 2009, about 570 nautical miles south-southwest of the southern tip of Baja California. It strengthened to a tropical storm later that day and moved generally west to west-northwest. Guillermo underwent rapid strengthening mid-life, became a major hurricane on August 15, and then gradually weakened as it moved northwest across the central Pacific. The system lost tropical characteristics by August 19 and its remnant low was absorbed by a cold front on August 23.

Guillermo did not make landfall. It stayed well offshore throughout its life and remained far to the north of the Hawaiian Islands as it weakened and transitioned to an extratropical cyclone.

The storm’s maximum intensity was 110 knots (127 mph) with a minimum central pressure of 954 mb, reached at 1200 UTC on August 15. At peak it was a Category 3 hurricane on the Saffir-Simpson scale.

Storm surge and rainfall impacts on land were not reported because Guillermo remained over open water and no coastal watches or warnings were required. There are no specific surge heights or rainfall totals for cities or counties associated with this storm.

There were no confirmed deaths, no reports of damage, and no injuries tied to Guillermo. The cyclone did produce measurable winds reported by two ships (38 kt and 37 kt) while it was north of Hawaii, but those observations did not correspond to land impacts.

A notable aspect of Guillermo was its rapid intensification into a major hurricane over open water and its unusually long persistence as a tropical storm at relatively high latitude in the central Pacific. Forecasts fairly well predicted its track, with official track errors below recent averages at most lead times, but the rapid strengthening was not well forecast and caused larger-than-normal intensity forecast errors.