Tropical Cyclone Billy passed south of Cocos Island on Tuesday. At 5:00 p.m. EDT on Tuesday the center of Tropical Cyclone Billy was located at latitude 17.8°S and longitude 94.8°E which put it about 385 miles (625 km) south-southwest of Cocos Island. Billy was moving toward the west-southwest at 12 m.p.h (19 km/h). The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h). The minimum surface pressure was 986 mb.

Tropical Cyclone Billy maintained its intensity over the South Indian Ocean on Tuesday as it passed south of Cocos Island. The inner end of a rainband wrapped around the center of circulation and an elliptical eye was evident on microwave satellite images. A band of strong thunderstorms surrounded the eye and the strongest winds were occurring in the southern part of the ring. A band of strong thunderstorms was south of the center of Billy. Bands in the other parts of the tropical cyclone consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 115 miles (185 km) in the southern half of Tropical Cyclone Billy. Winds to tropical storm force extended out 40 miles (65 km) in the northern half of the circulation.

Tropical Cyclone Billy will move through an environment unfavorable for intensification during the next several days. Billy will move over water where the Sea Surface Temperatures are near 26˚C. It will move north of an upper level trough over the South Indian Ocean. The trough will produce westerly winds that will blow toward the top of Billy’s circulation. Those winds will cause moderate vertical wind shear. There will be drier air north and west of Tropical Cyclone Billy. The drier air will also inhibit intensification. A combination of moderate vertical wind shear and drier air will cause Tropical Cyclone Billy to weaken gradually during the next several days.

Tropical Cyclone Billy will move around the northern part of a high pressure system centered west of Australia. The high pressure system will steer Billy toward the west-southwest during the next several days. On its anticipated track Tropical Cyclone Billy will move farther away from Cocos Island.

Tropical Cyclone Billy strengthened south-southeast of Cocos Island on Monday. At 5:00 p.m. EDT on Monday the center of Tropical Cyclone Billy was located at latitude 16.8°S and longitude 98.4°E which put it about 330 miles (530 km) south-southeast of Cocos Island. Billy was moving toward the southwest at 12 m.p.h (19 km/h). The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h). The minimum surface pressure was 983 mb.

A low pressure system over the South Indian Ocean south-southeast of Cocos Island strengthened on Monday and the Australian Bureau of Meteorology designated the system as Tropical Cyclone Billy. An eye was apparent on microwave satellite imagery at the center of Tropical Cyclone Billy earlier on Monday, but the eye was gone by later in the afternoon. A partial ring of thunderstorms surrounded the center of Billy’s circulation and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Tropical Cyclone Billy. Storms near the core generated upper level divergence that pumped mass away from the tropical cyclone. Winds to tropical storm force extended out 110 miles (175 km) from the center of Billy.

Tropical Cyclone Billy will move through an environment marginally favorable for intensification during the next 24 hours. Billy will move over water where the Sea Surface Temperatures are near 27˚C. It will move through a region where the upper level winds are weak and there will not be a lot of vertical wind shear. However, there appears to be drier air north and west of Tropical Cyclone Billy. The drier air seems to have been pulled into the core of Billy’s circulation and it may have contributed to the disappearance of the eye on Monday. The drier air will inhibit intensification. Tropical Cyclone Billy could strengthen if more thunderstorms develop around the center of circulation, but the drier air may prevent that from happening.

Tropical Cyclone Billy will move around the northern part of a high pressure system centered west of Australia. The high pressure system will steer Billy toward the west-southwest during the next several days. On its anticipated track Tropical Cyclone Billy will pass south of Cocos Island in 24 hours.