Tropical Cyclone Grant weakened as it moved over the South Indian Ocean northeast of Rodrigues on Thursday. At 10:00 p.m. EST on Thursday the center of Tropical Cyclone Grant was located at latitude 15.7°S and longitude 67.1°E which put the center about 370 miles (600 km) northeast of Rodrigues. Grant was moving toward the west-northwest at 5 m.p.h. (8 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 997 mb.
Tropical Cyclone Grant weakened rapidly on Thursday. An upper level ridge over the South Indian Ocean produced easterly winds that blew toward the top of Grant’s circulation. Those winds caused strong vertical wind shear. The strong wind shear caused Tropical Cyclone Grant to weaken rapidly.
The strong vertical wind shear also affected the structure of Tropical Cyclone Grant. Thunderstorms were still occurring in bands in the western half of Grant’s circulation. Bands in the eastern half of Grant consisted primarily of showers and lower clouds. Storms near the center of Grant still generated upper level divergence that pumped mass away to the west of the tropical cyclone. However, the removal of mass in the upper levels was much less than the convergence of mass in the lower levels of the atmosphere. So, the surface pressure increased rapidly on Thursday.
The circulation around Tropical Cyclone Grant was small. Winds to tropical storm force extended out 100 miles (160 km) from the center of Grant’s circulation.
Tropical Cyclone Grant will move through an environment that will be marginally favorable for intensification during the next 24 hours. Grant will move over water where the Sea Surface Temperatures are near 28°C. It will move under the northern part of an upper level ridge over the South Indian Ocean. The upper level ridge will continue to produce easterly winds that will blow toward the top of Grant’s circulation. Those winds will cause moderate vertical wind shear. The moderate wind shear will inhibit intensification. Tropical Cyclone Grant is likely to maintain its intensity during the next 24 hours.
Tropical Cyclone Grant will move around the northern side of a high pressure system over the South Indian Ocean. The high pressure system will steer Grant toward the west during the next 24 hours. On its anticipated track, Tropical Cyclone Grant will pass north of Rodrigues on Saturday. Grant will pass north of Mauritius and La Reunion on Monday.
Elsewhere over the South Indian Ocean, Tropical Cyclone Iggy moved farther away from Christmas Island. At 10:00 p.m. EST on Thursday the center of Tropical Cyclone Iggy was located at latitude 15.4°S and longitude 106.5°E which put the center about 425 miles (685 km) south-southeast of Christmas Island. Iggy was moving toward the south-southeast at 8 m.p.h. (13 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 1000 mb.
