The tropical Eastern North Pacific Ocean continued to be very active on Tuesday with Hurricane Fernanda, Tropical Storm Greg and Tropical Depression Eight-E. At 11:00 p.m. EDT on Tuesday the center of Hurricane Fernanda was located at latitude 16.5°N and longitude 134.4°W which put it about 1375 miles east of Hilo, Hawaii. Fernanda was moving toward the northwest at 9 m.p.h. (15 km/h). The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h). The minimum surface pressure was 976 mb.
At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Greg was located at latitude 14.6°N and longitude 110.1°W which put it about 490 miles (785 km) southwest of Manzanillo, Mexico. Greg was moving toward the west at 10 m.p.h. (16 km/h). The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h). The minimum surface pressure was 1003 mb.
At 11:00 p.m. EDT on Tuesday the center of Tropical Depression Eight-E was located at latitude 14.8°N and longitude 119.9°W which put it about 860 miles (1385 km) southwest of the southern tip of Baja California. It was moving toward the west at 5 m.p.h. (8 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 1007 mb.
Although Hurricane Fernanda is the strongest of the three tropical cyclones over the Eastern North Pacific Ocean, it is slowly weakening as it moves over cooler Sea Surface Temperatures (SSTs). Hurricane Fernanda is over water where the SSTs are near 26.5°C and it will move over cooler water as it moves west toward Hawaii.
Tropical Storm Greg strengthened on Tuesday as it moved over water where the SSTs are near 29°C. A primary rainband wrapped around the western side of the center of circulation. Additional showers and thunderstorms formed closer to the center. Greg is also expected to move west as it moves south of a subtropical ridge.
The future of Tropical Depression Eight-E is less certain. Upper level divergence from Hurricane Fernanda is creating strong vertical wind shear over the stop of the depression. The strong wind shear is causing the circulation of the depression to be poorly organized. There are few showers and thunderstorms in the northern portion of the circulation because of the strong shear. The stronger upper level winds could shear the top of the circulation away from the lower level circulation of the depression. It is also possible that Tropical Storm Greg could catch up to the depression and absorb the remnants of the depression into its circulation.
Hurricane Fernanda weakened slowly as it moved farther west over the Eastern North Pacific Ocean on Sunday. At 11:00 p.m. EDT on Sunday the center of Hurricane Fernanda was located at latitude 13.0°N and longitude 129.2°W which put it about 1440 miles (2315 km) west-southwest of the southern tip of Baja California. Fernanda was moving toward the west-northwest at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 140 m.p.h. (220 km/h). The minimum surface pressure was 960 mb.
Hurricane Fernanda completed at least one eyewall replacement cycle in which an outer eyewall formed around the original eyewall. Eventually, the inner eyewall dissipated and a larger eye formed inside the outer eyewall. The eyewall replacement cycle weakened Hurricane Fernanda when the stronger, inner eyewall dissipated. Although Hurricane Fernanda is weaker, it is still a powerful hurricane. There is a circular eye at the center of circulation. A ring of strong thunderstorms still surrounds the eye and the strongest winds are occurring in that ring of storms. Additional bands of showers and thunderstorms are revolving around the core of the circulation. Thunderstorms in the core of Hurricane Fernanda are generating strong upper level divergence which are pumping out mass in all directions.
Hurricane Fernanda is moving over water where the Sea Surface Temperature (SST) is near 29°C. The upper level winds are weak and there is little vertical wind shear. Fernanda will gradually move over cooler SSTs. When Fernanda moves over the cooler SSTs, it will extract less energy from the ocean and the hurricane will continue to weaken. The weakening could occur very gradually because the wind shear is limited.
Hurricane Fernanda is moving south of a subtropical high pressure system which is steering the hurricane toward the west-northwest. The subtropical high is expected to steer Fernanda toward the west-northwest during the next several days.
Hurricane Fernanda intensified rapidly to Category 4 on the Saffir-Simpson Scale on Friday. At 5:00 p.m. EDT on Friday the center of Hurricane Fernanda was located at latitude 10.7°N and longitude 119.7°W which put it about 1060 miles (1710 km) southwest of the southern tip of Baja California. Fernanda was moving toward the west at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 130 m.p.h. (215 km/h) and there were wind gusts to 155 m.p.h. (250 km/h). The minimum surface pressure was 960 mb.
A clear circular eye formed at the center of Hurricane Fernanda. The eye is surrounded by a ring of very strong thunderstorms and the strongest winds are occurring in the eyewall. Additional bands of showers and thunderstorms formed outside the core of Fernanda. There are more bands in the eastern half of the hurricane, but the overall circulation is fairly symmetrical. The thunderstorms in the core of Fernanda are generating strong upper level divergence which is pumping mass away from the hurricane.
Fernanda is a small hurricane. Winds to hurricane force only extend out about 25 miles (40 km) from the center of circulation. Winds to tropical storm force only extend out about 70 miles (110 km) from the center. The Hurricane Intensity Index (HII) is 25.1. The Hurricane Size Index (HSI) is 9.0 and the Hurricane Wind Intensity Size Index (HWISI) is 34.1. The indices indicate that Hurricane Fernanda is somewhat similar in size and strength to Hurricane Charley in 2004 when Charley was approaching the southwest coast of Florida.
Hurricane Fernanda will remain in an environment very favorable for intensification for another 24 to 48 hours. It will move over water where the Sea Surface Temperature (SST) is near 28.5°C. The upper level winds are weak and there is little vertical wind shear. Hurricane Fernanda has a chance to intensify into a Category 5 hurricane on the Saffir-Simpson Scale before it moves into a less favorable environment. When a hurricane becomes as intense as Hurricane Fernanda is, an outer rainband can wrap around the eye and an eyewall replacement cycle can occur. If an eyewall replacement cycle occurs in Hurricane Fernanda, then fluctuations in intensity may also happen. Eventually Fernanda will move over cooler SSTs and the hurricane will start to weaken.
Hurricane Fernanda is moving south of a subtropical ridge and the ridge is steering the hurricane a little south of due west. A general westward motion is forecast to continue during the next few days. On its anticipated track Hurricane Fernanda will continue to move farther away from Mexico. Fernanda could approach Hawaii by the end of next week.
Former Tropical Storm Fernanda rapidly intensified into a hurricane on Thursday. At 5:00 p.m. EDT on Thursday the center of Hurricane Fernanda was located at latitude 11.2°N and longitude 116.0°W which put it about 900 miles (1450 km) south-southwest of the southern tip of Baja California. Fernanda was moving toward the west at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155 km/h). The minimum surface pressure was 990 mb.
A primary rainband wrapped around the center of circulation and an eye appeared intermittently on visible satellite images on Thursday afternoon. The improved organization of the inner core of Fernanda allowed it to intensify rapidly into a hurricane. The distribution of thunderstorms become more symmetrical and circulation exhibited a more circular appearance. Thunderstorms in the inner core began to generate strong upper level divergence which pumped out mass in all directions. The divergence of mass allowed the surface pressure to decrease and the wind speeds to increase rapidly.
Hurricane Fernanda will move through an environment that will be favorable for further intensification during the next two days. Fernanda will move over water where the Sea Surface Temperature (SST) is near 29°C. An upper level ridge northeast of Fernanda is producing easterly winds which are blowing toward the top of the hurricane. However, the speed of the upper level winds decreased on Thursday and there is less vertical wind shear. A combination of a well organized inner core, warm SSTs and reduced vertical wind shear resulted in rapid intensification of Fernanda into a hurricane. Rapid intensification could continue for another 24 to 36 hours and Fernanda is forecast to become a major hurricane on Friday.
A subtropical ridge to the north of Fernanda is steering the hurricane toward the west and a general westerly motion is expected to continue for several more days. On its anticipated track Hurricane Fernanda will move farther away from Mexico.