Hurricane Fernanda Intensifies Rapidly to Category 4

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.

Leave a Reply

Your email address will not be published. Required fields are marked *