Tropical Cyclone Marian intensified to the equivalent of a major hurricane over the South Indian Ocean southwest of Cocos Island on Sunday. At 10:00 a.m. EST on Sunday the center of Tropical Cyclone Marian was located at latitude 17.5°S and longitude 91.1°E which put it about 520 miles (835 km) southwest of Cocos Island. Marian was moving toward the southwest at 6 m.p.h. (10 km/h). The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 145 m.p.h. (235 km/h). The minimum surface pressure was 952 mb.
Tropical Cyclone Marian intensified rapidly into the equivalent of a major hurricane during the past 24 hours. A circular eye with a diameter of 35 miles (55 km) formed at the center of Marian. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Storms near the core of the circulation generated strong upper level divergence that pumped mass away from the tropical cyclone. Bands of showers and thunderstorms were revolving around the core of Tropical Cyclone Marian.
The area of the strongest winds expanded as Tropical Cyclone Marian intensified rapidly. Winds to hurricane/typhoon force extended out 45 miles (75 km) from the center of Marian. Winds to tropical storm force extended out 185 miles (295 km) from the center of circulation. The Hurricane Intensity Index (HII) for Tropical Cyclone Marian was 20.6. The Hurricane Size Index (HSI) was 17.7 and the Hurricane Wind Intensity Size Index (HWISI) was 38.3.
Tropical Cyclone Marian will move through an environment favorable for intensification during the next 12 hours. Marian will move over water where the Sea Surface Temperatures will be near 28°C. It will move under the western portion of an upper level ridge. The upper level winds will be weak during the next 12 hours and there will not be a lot of vertical wind shear. Tropical Cyclone Marian could intensify during the next 12 hours. Marian will move closer to upper level westerly winds in the middle latitudes early next week. The vertical wind shear will increase at that time and Tropical Cyclone Marian will weaken.
Tropical Cyclone Marian will move around the western part of a subtropical high pressure system during the next 36 hours. The high will steer Marian toward the southwest during the next 18 hours. On its anticipated track Tropical Cyclone Marian will move farther away from Cocos Island. After Marian moves around the western end of the high pressure system, the tropical cyclone will start to move toward the southeast..