Hurricane Douglas Prompts Watches for Hawaii

Hurricane Douglas prompted the issuance of Hurricane Watches for some of the Hawaiian Islands on Friday afternoon.  At 5:00 p.m. EDT on Friday the center of Hurricane Douglas was located at latitude 17.0°N and longitude 143.5°W which put it about 785 miles (1260 km) east of Hilo, Hawaii.  Douglas was moving toward the west-northwest at 18 m.p.h. (30 km/h).  The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 140 m.p.h. (225 km/h).  The minimum surface pressure was 967 mb.

Hurricane Watches were issued for Hawaii, Maui, Lanai, Molokai and Kahoolawe.

Hurricane Douglas continued on a track toward the Hawaiian Islands on Friday, which prompted the issuance of Hurricane Watches.  Douglas was weakening slowly as it moved over slightly cooler water.  In addition, Hurricane Douglas appeared to go through an eyewall replacement cycle which may have contributed to the weakening.  Even though it had weakened, Douglas remained a powerful, well organized hurricane.  There was a circular eye at the center of circulation.  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 core of Hurricane Douglas.  Storms near the core were generating upper level divergence which was pumping mass away from the hurricane.

Winds to hurricane force extended out 25 miles (40 km) from the center of circulation.  Winds to tropical storm force extended out 120 miles (195 km) from the center of Douglas.  The Hurricane Intensity Index (HII) for Hurricane Douglas was 20.6.  The Hurricane Size Index (HSI) was 9.9 and the Hurricane Wind Intensity Size Index (HWISI) was 30.5.  Hurricane Douglas was capable of causing localized major damage.

Hurricane Douglas will move through an environment less favorable for major hurricanes during the next several days.  Douglas will move over water where the Sea Surface Temperature is near 25°C.  So, Hurricane Douglas will not be able to extract as much energy from the upper ocean.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  The lack of wind shear will allow Hurricane Douglas to weaken gradually.

Hurricane Douglas will move south of a subtropical high pressure system over the Eastern and Central North Pacific Ocean.  The high will steer Douglas toward the west-northwest.  On its anticipated track Hurricane Douglas will approach Hawaii on Sunday.