Tropical Cyclone Batsirai Rapidly Intensifies to Equivalent of a Major Hurricane

Tropical Cyclone Batsirai rapidly intensified to the equivalent of a major hurricane on Tuesday night. At 10:00 p.m. EST on Tuesday the center of Tropical Cyclone Batsirai was located at latitude 18.3°S and longitude 57.9°E which put it about 155 miles (250 km) northeast of Port Louis, Mauritius. Batsirai was moving toward the southwest at 11 m.p.h. (17 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. (270 km/h). The minimum surface pressure was 915 mb.

Tropical Cyclone Batsirai rapidly intensified to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale on Tuesday night. The core of Batsirai contracted around a tiny pinhole eye. 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 Batsirai. Storms near the core generated strong upper level divergence that large quantities of mass away from the tropical cyclone. The removal of that much mass allowed the surface pressure to decrease rapidly.

Tropical Cyclone Batsirai increased in size as it intensified rapidly. Winds to hurricane/typhoon force extended out 45 miles (75 km) from the center of Batsirai. Winds to tropical storm force extended out 195 miles (315 km) from the center of circulation. The Hurricane Intensity Index (HII) for Tropical Cyclone Batsirai was 28.3. The Hurricane Size Index (HSI) was 18.3 and the Hurricane Wind Intensity Size Index (HWISI) was 46.6.

Tropical Cyclone Batsirai will move through an environment capable of supporting a strong tropical cyclone during the next 48 hours. Batsirai will move over water where the Sea Surface Temperatures are near 29˚C. It will move under the northern part of an upper level ridge over the Southwest Indian Ocean. The ridge will produced easterly winds that will blow toward the top of Batsirai’s circulation. Those winds will cause some vertical wind shear and the wind shear could inhibit additional intensification. If the inner end of a rainband wraps around the existing eye and eyewall, then an eyewall replacement cycle could begin. If an eyewall replacement cycle occurs Tropical Cyclone Batsirai is likely to weaken, at least temporarily.

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-southwest during the next several days. On its anticipated track the center of Tropical Cyclone Batsirai will pass north of Mauritius during the next 12 hours. Although the strongest winds in Batsirai will pass north of Mauritius, it could experience tropical storm force winds and locally heavy rain. Locally heavy rain could cause flash floods in some locations. Tropical Cyclone Batsirai will be north of La Reunion in 24 hours. Batsirai could reach the east coast of Madagascar within 72 hours. Tropical Cyclone Batsirai could still be the equivalent of a major hurricane when it reaches Madagascar.