Tropical Cyclone Djoungou strengthened to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale over the South Indian Ocean on Sunday. At 4:00 p.m. EST on Sunday the center of Tropical Cyclone Djoungou was located at latitude 22.5°S and longitude 82.3°E which put it about 1150 miles (1855 km) south-southeast of Diego Garcia. Djoungou was moving toward the southeast at 33 m.p.h. (54 km/h). The maximum sustained wind speed was 140 m.p.h. (220 km/h) and there were wind gusts to 165 m.p.h. (265 km/h). The minimum surface pressure was 942 mb.

A small circular was visible at the center of Tropical Cyclone Djoungou earlier on Sunday, but the eye was no longer evident on Sunday afternoon. The eye was surrounded by a ring of 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 Djoungou. Storms near the core generated strong upper level divergence that pumped lmass away from the tropical cyclone.

The size of the circulation around Tropical Cyclone Djoungou increased on Sunday. Winds to hurricane/typhoon force extended out 70 miles (110 km) from the center of Djoungou’s circulation. Winds to tropical storm force extended out 200 miles (320 km) from the center of circulation. The Hurricane Intensity Index (HII) for Tropical Cyclone Djoungou was 28.2. The Hurricane Size Index (HSI) was 25.7 and the Hurricane Wind Intensity Size Index (HWISI) was 53.9.

Tropical Cyclone Djoungou will move through an environment unfavorable for a strong tropical cyclone during the next 36 hours. Djoungou will move over water where the Sea Surface Temperatures are near 26°C. It will move under the eastern part of an upper level trough over the South Indian Ocean. The upper level trough will produce strong northwesterly winds that will blow toward the top of Djoungou’s circulation. Those winds will cause strong vertical wind shear. Strong vertical wind shear and cooler water will cause Tropical Cyclone Djoungou to weaken rapidly during the next 36 hours.

Tropical Cyclone Djoungou will move around the southern side of a high pressure system over the South Indian Ocean. The high pressure system will steer Djoungou toward the east-southeast during the next 36 hours. On its anticipated track, Tropical Cyclone Djoungou will move far to the south of the Cocos Islands in 36 hours.

Elsewhere over the South Indian Ocean, a tropical depression formed northwest of Mauritius. At 1:00 p.m. EST on Sunday the center of the tropical depression was located at latitude 15.5°S and longitude 5363°E which put it about 405 miles (650 km) northwest of Port Louis, Mauritius. The tropical depression was moving toward the east-northeast at 11 m.p.h. (17 km/h). The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h). The minimum surface pressure was 1004 mb.