Hurricane Dora passed south of Johnston Island early on Thursday. At 5:00 a.m. EDT on Thursday the center of Hurricane Dora was located at latitude 12.1°N and longitude 169.8°W which put it about 320 miles (510 km) south of Johnston Island. Dora was moving toward the west at 22 m.p.h. (35 km/h). The maximum sustained wind speed was 140 m.p.h. (225 km/h) and there were wind gusts to 165 m.p.h. (265 km/h). The minimum surface pressure was 950 mb.

The structure of Hurricane Dora showed signs of changing early on Thursday. The eye at the center of Dora’s circulation got smaller and the eye was more difficult to see on infrared satellite images. Several new bands of thunderstorms developed in the eastern and northern parts of Hurricane Dora. Dora was still a powerful hurricane. Storms near the center of Dora generated upper level divergence that pumped mass away from the hurricane.

The size of the circulation around Hurricane Dora increased a little as its structure began to change. Winds to hurricane force extended out 30 miles (50 km) from the center of Dora’s circulation. Winds to tropical storm force extended out 115 miles (185 km) from the center of circulation. The Hurricane Intensity Index (HII) was 28.3. The Hurricane Size Index (HSI) was 9.9 and the Hurricane Wind Intensity Size Index (HWISI) was 38.2. Hurricane Dora was similar in size and intensity to Hurricane Charley when Charley hits southwest Florida in 2004.

Hurricane Dora will move through an environment that will be favorable for a major hurricane during the next 24 hours. Dora 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 Dora could be starting an eyewall replacement cycle. If an eyewall replacement cycle is beginning, then Dora is likely to weaken during the next 24 hours, even though the hurricane will be in a favorable environment. Since the circulation around Hurricane Dora is so small, any changes in the environment will have large effects on the intensity of Dora.

Hurricane Dora will move south of a subtropical high pressure system over the North Pacific Ocean. The high pressure system will steer Dora toward the west-northwest during the next 24 hours. On its anticipated track, Hurricane Dora will be move west of the International Date Line on Friday.