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Tropical Cyclone Batsirai Rapidly Intensifies to Equivalent of Hurricane/Typhoon

Tropical Cyclone Batsirai rapidly intensified to the equivalent of a hurricane/typhoon over the South Indian Ocean on Thursday morning. At 7:00 a.m. EST on Thursday the center of Tropical Cyclone Batsirai was located at latitude 17.9°S and longitude 79.7°E which put it about 1090 miles (1760 km) east-northeast of Rodrigues. Batsirai was moving toward the west-southwest at 25 m.p.h. (40 km/h). The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (200 km/h). The minimum surface pressure was 968 mb.

Tropical Cyclone Batsirai rapidly intensified from a tropical storm to the equivalent of a Category 2 hurricane on the Saffir-Simpson Scale after it developed over the South Indian Ocean on Wednesday night. A tiny pinhole eye with a diameter of 8 miles (13 km) quickly formed at the center of Batsirai’s circulation. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. The strongest winds were occurring about 6 miles (10 km) from the center of circulation. Bands of showers and thunderstorms were revolving around the core of Tropical Cyclone Batsirai. Storms near the core generated strong upper level divergence that pumped mass away from the tropical cyclone.

The circulation around Tropical Cyclone Batsirai was very small. Winds to hurricane/typhoon force extended out 25 miles (40 km) from the center of Batsirai. Winds to tropical storm force extended out 50 miles (80 km) from the center of circulation. The Hurricane Intensity Index (HII) for Tropical Cyclone Batsirai was 17.8. The Hurricane Size Index (HSI) was 8.6 and the Hurricane Wind Intensity Size Index (HWISI) was 24.4.

Tropical Cyclone Batsirai will move through an environment favorable for intensification during the next 24 hours. Batsirai will move over water where the Sea Surface Temperatures are near 29˚C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Tropical Cyclone Batsirai could continue to intensify rapidly during the next few hours. However, if the inner end of a rainband wraps around the existing eye and eyewall, then an eyewall replacement cycle could cause Batsirai to weaken. Since the circulation around Batsirai is very small, if the tropical cyclone moves into a less favorable environment, it could weaken rapidly.

Tropical Cyclone Batsirai will move north of a high pressure system over the South Indian Ocean. The high pressure system will steer Batsirai toward the west during the next few days. On its anticipated track Tropical Cyclone Batsirai could approach Rodrigues, Mauritius, La Reunion and eventually Madagascar next week. Batsirai could be the equivalent of a hurricane/typhoon when it approaches those places.