Tropical Cyclone Halima Rapidly Intensifies to Equivalent of a Major Hurricane

Tropical Cyclone Halima rapidly intensified to the equivalent of a major hurricane over the South Indian Ocean south of Diego Garcia on Friday. At 11:00 a.m. EDT on Friday the center of Tropical Cyclone Halima was located at latitude 14.6°S and longitude 73.4°E which put it about 495 miles (795 km) south of Diego Garcia. Halima was moving toward the south-southwest at 6 m.p.h (10 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 918 mb.

Tropical Cyclone Halima rapidly intensified to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale during the past 24 hours. A small circular eye with a diameter of 10 miles (16 km) was at the center of Halima’s 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 Tropical Cyclone Halima. Storms near the core of the circulation generated strong upper level divergence that pumped large quantities of mass away from the tropical cyclone. The removal of mass allowed the surface pressure to decrease rapidly.

The circulation around Tropical Cyclone Halima was small. Winds to hurricane/typhoon force extended out 25 miles (40 km) from the center of Halima. Winds to tropical storm force extended out 100 miles (160 km) from the center of circulation. The Hurricane Intensity Index (HII) for Tropical Cyclone Halima was 28.3. The Hurricane Size Index (HSI) was 9.4 and the Hurricane Wind Intensity Size Index (HWISI) was 37.7.

Tropical Cyclone Halima will move through an environment capable of supporting a strong tropical cyclone during the next 24 hours. Halima will move over water where the Sea Surface Temperatures are near 28˚C. It will move under the axis of an upper level ridge over the South Indian Ocean. The winds are weaker near the axis of the ridge and there will be little vertical wind shear. Tropical Cyclone Halima could continue to intensify during the next 24 hours. If the inner end of a rainband wraps around the existing small eye and eyewall, then concentric eyewalls could form. Concentric eyewalls would be the beginning of an eyewall replacement cyclone that would cause Halima to weaken.

Tropical Cyclone Halima will move around the western end of a high pressure system over the South Indian Ocean during the next 24 hours. The high pressure system will steer Halima toward the south. On its anticipated track Tropical Cyclone Halima will continue to move farther away from Diego Garcia.