Darby Rapidly Intensifies to a Major Hurricane

Hurricane Darby rapidly intensified to a major hurricane over the Eastern North Pacific Ocean between Mexico and Hawaii on Monday morning. At 11:00 a.m. EDT on Monday the center of Hurricane Darby was located at latitude 14.6°N and longitude 123.4°W which put it about 1050 miles (1690 km) west-southwest of the southern tip of Baja California. Darby was moving toward the west at 15 m.p.h. (24 km/h). The maximum sustained wind speed was 125 m.p.h. (200 km/h) and and there were wind gusts to 150 m.p.h. (240 km/h). The minimum surface pressure was 965 mb.

Hurricane Darby continued to intensify rapidly on Monday morning. A circular eye with a diameter of 12 miles (19 km) was at the center of Hurricane Darby. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the small core of Hurricane Darby. Storms near the core generated strong upper level divergence that pumped mass away from the hurricane. Winds to hurricane force extended out 15 miles (25 km) from the center of Darby’s circulation. Winds to tropical storm force extended out 60 miles (95 km) from the center of circulation.

The circulation around Hurricane Darby was small but very symmetrical. Darby looked like a small, annular hurricane. The Hurricane Intensity Index (HII) for Hurricane Darby was 23.6. The Hurricane Size Index (HSI) was 5.4 and the Hurricane Wind Intensity Size Index (HWISI) was 29.0.

Hurricane Darby will move through an environment favorable for intensification during the next 18 hours. Darby will move over water where the Sea Surface Temperatures are near 28˚C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Hurricane Darby could continue to intensify during the 18 hours. The small size of the circulation around Hurricane Darby means that the intensity could continue to change rapidly if the environmental conditions change. If the inner end of a rainband wraps around the small core of Darby’s circulation, then an eyewall replacement cycle could cause Hurricane Darby to weaken.

Hurricane Darby will move around the southern side of a high pressure system over the Eastern North Pacific Ocean. The high pressure system will steer Darby toward the west during the next 24 hours. On its anticipated track Hurricane Darby will move farther away from Baja California. Darby will cross into the Central Pacific Ocean later this week.