Category Archives: Indian Ocean

Tropical Cyclone Halima Continues to Weaken

Tropical Cyclone Halima continued to weaken over the South Indian Ocean south of Diego Garcia on Sunday. At 11:00 p.m. EDT on Sunday the center of Tropical Cyclone Halima was located at latitude 21.7°S and longitude 80.7°E which put it about 1120 miles (1805 km) south-southeast of Diego Garcia. Halima was moving toward the southeast at 8 m.p.h (13 km/h). The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h). The minimum surface pressure was 996 mb.

An upper level trough over the South Indian Ocean continued to produce northwesterly winds that blew toward the top of Halima’s circulation. Those winds caused moderate vertical wind shear. The wind shear caused Tropical Cyclone Halima to continue to weaken. The inner end of a rainband wrapped around the center of Halima’s circulation, but the distribution of thunderstorms remained asymmetrical. Most of the thunderstorms were occurring in bands in the southern half of Tropical Cyclone Halima. Bands in the northern half of the circulation consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 100 miles (160 km) from the center of circulation.

Tropical Cyclone Halima will move through an environment that will continue to be unfavorable for intensification during the next 24 hours. Halima will move over water where the Sea Surface Temperatures are near 26˚C. However, the upper level trough will continue to produce moderate vertical wind shear. The wind shear will cause Tropical Cyclone Halima to continue to weaken during the next 24 hours.

The upper level trough will steer Tropical Cyclone Halima toward the east during the next 24 hours. On its anticipated track Tropical Cyclone Halima will move farther away from Diego Garcia. If the thunderstorms in the southern half of Halima’s circulation dissipate, then the tropical cyclone will only exist in the lower levels of the atmosphere. If that happens, then the winds in the lower levels could turn Tropical Cyclone Halima back toward the north.

Tropical Cyclone Halima Weakens South of Diego Garcia

Tropical Cyclone Halima weakened over the South Indian Ocean south of Diego Garcia on Saturday. At 11:00 p.m. EDT on Saturday the center of Tropical Cyclone Halima was located at latitude 20.0°S and longitude 76.4°E which put it about 890 miles (1440 km) south-southeast of Diego Garcia. Halima was moving toward the southeast at 17 m.p.h (28 km/h). The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h). The minimum surface pressure was 981 mb.

Tropical Cyclone Halima weakened on Saturday when it moved into an environment that included more vertical wind shear. An upper level trough over the South Indian Ocean produced northwesterly winds that blew toward the top of Halima’s circulation. Those winds produced moderate vertical wind shear. The wind shear affected the structure of Tropical Cyclone Halima. The former small eyewall became fragmented. In addition, the stronger thunderstorms were occurring in bands in the southern half of Halima’s circulation. Bands in the northern half of the circulation consisted primarily of showers and lower clouds. Winds to hurricane/typhoon force extended out 15 miles (25 km) from the center of Tropical Cyclone Halima. Winds to tropical storm force extended out 105 miles (165 km) from the center of circulation.

Tropical Cyclone Halima will move through an environment that will continue to be unfavorable for intensification during the next 36 hours. Halima will move over water where the Sea Surface Temperatures are near 26˚C. However, the upper level trough will continue to produce moderate vertical wind shear. The wind shear will cause Tropical Cyclone Halima to continue to weaken during the next 36 hours.

The upper level trough will continue to steer Tropical Cyclone Halima toward the southeast during the next 24 hours. On its anticipated track Tropical Cyclone Halima will move farther away from Diego Garcia.

Tropical Cyclone Halima Rapidly Intensifies to Equivalent of a Major Hurricane

Tropical Cyclone Halima rapidly intensified to the equivalent of a major hurricane over the South Indian Ocean south of Diego Garcia on Friday. At 11:00 a.m. EDT on Friday the center of Tropical Cyclone Halima was located at latitude 14.6°S and longitude 73.4°E which put it about 495 miles (795 km) south of Diego Garcia. Halima was moving toward the south-southwest at 6 m.p.h (10 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. (265 km/h). The minimum surface pressure was 918 mb.

Tropical Cyclone Halima rapidly intensified to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale during the past 24 hours. A small circular eye with a diameter of 10 miles (16 km) was at the center of Halima’s circulation. 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 Halima. Storms near the core of the circulation generated strong upper level divergence that pumped large quantities of mass away from the tropical cyclone. The removal of mass allowed the surface pressure to decrease rapidly.

The circulation around Tropical Cyclone Halima was small. Winds to hurricane/typhoon force extended out 25 miles (40 km) from the center of Halima. Winds to tropical storm force extended out 100 miles (160 km) from the center of circulation. The Hurricane Intensity Index (HII) for Tropical Cyclone Halima was 28.3. The Hurricane Size Index (HSI) was 9.4 and the Hurricane Wind Intensity Size Index (HWISI) was 37.7.

Tropical Cyclone Halima will move through an environment capable of supporting a strong tropical cyclone during the next 24 hours. Halima will move over water where the Sea Surface Temperatures are near 28˚C. It will move under the axis of an upper level ridge over the South Indian Ocean. The winds are weaker near the axis of the ridge and there will be little vertical wind shear. Tropical Cyclone Halima could continue to intensify during the next 24 hours. If the inner end of a rainband wraps around the existing small eye and eyewall, then concentric eyewalls could form. Concentric eyewalls would be the beginning of an eyewall replacement cyclone that would cause Halima to weaken.

Tropical Cyclone Halima will move around the western end of a high pressure system over the South Indian Ocean during the next 24 hours. The high pressure system will steer Halima toward the south. On its anticipated track Tropical Cyclone Halima will continue to move farther away from Diego Garcia.

Tropical Cyclone Halima Strengthens to Equivalent of Hurricane/Typhoon

Tropical Cyclone Halima strengthened to the equivalent of a hurricane/typhoon over the South Indian Ocean south of Diego Garcia on Thursday. At 11:00 a.m. EDT on Thursday the center of Tropical Cyclone Halima was located at latitude 13.2°S and longitude 74.3°E which put it about 435 miles (700 km) south-southeast of Diego Garcia. Halima was moving toward the west at 6 m.p.h (10 km/h). The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h). The minimum surface pressure was 979 mb.

Tropical Cyclone Halima intensified to the equivalent of a hurricane/typhoon on Thursday. A small circular eye with a diameter of 10 miles (16 km) formed at the center of Halima’s circulation. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Other strong thunderstorms were occurring in bands in the western half of Tropical Cyclone Halima. Bands in the eastern half of the circulation consisted primarily of showers and lower clouds. Storms near the center of Halima’s circulation generated upper level divergence that pumped mass away from the tropical cyclone. Winds to hurricane/typhoon force extended out 25 miles (40 km) from the center of Tropical Cyclone Halima. Winds to tropical storm force extended out 115 miles (185 km) from the center of circulation.

Tropical Cyclone Halima will move through an environment favorable for intensification during the next 36 hours. Halima will move over water where the Sea Surface Temperatures are near 28˚C. It will move under the axis of an upper level ridge over the South Indian Ocean. The winds are weaker near the axis of the ridge and there will be little vertical wind shear. Tropical Cyclone Halima will intensify during the next 36 hours and it could strengthen to the equivalent of a major hurricane.

Tropical Cyclone Halima will move around the western end of a high pressure system over the South Indian Ocean during the next 36 hours. The high pressure system will steer Halima toward the south. On its anticipated track Tropical Cyclone Halima will move farther away from Diego Garcia.

Tropical Cyclone Halima Forms South of Diego Garcia

Tropical Cyclone Halima formed south of Diego Garcia on Wednesday. At 11:00 a.m. EDT on Wednesday the center of Tropical Cyclone Halima was located at latitude 13.4°S and longitude 75.7°E which put it about 485 miles (780 km) south-southeast of Diego Garcia. Halima was moving toward the west-southwest at 9 m.p.h (15 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.

The circulation around a low pressure system over the South Indian Ocean south of Diego Garcia strengthened on Wednesday and the system was designated at Tropical Cyclone Halima. More thunderstorms formed west of the center of Halima’s circulation. The strongest thunderstorms were occurring in bands in the western half of Tropical Cyclone Halima. Bands in the eastern half of the circulation consisted primarily of showers and lower clouds. Storms near the center of circulation generated upper level divergence that pumped mass away from the tropical cyclone. Winds to tropical storm force extended out 90 miles (145 km) from the center of Halima.

Tropical Cyclone Halima will move through an environment favorable for intensification during the next 36 hours. Halima 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 ridge will produce easterly winds that will blow toward the top of Halima’s circulation. Those winds will cause some vertical wind shear, but the shear will not be enough to prevent intensification. Tropical Cyclone Halima will intensify during the next 36 hours and it could strengthen to the equivalent of a hurricane/typhoon.

Tropical Cyclone Halima will move around the western end of a high pressure system over the South Indian Ocean during the next 36 hours. The high pressure system will steer Halima toward the south. On its anticipated track Tropical Cyclone Halima will move farther away from Diego Garcia.

Elsewhere over the South Indian Ocean, Tropical Cyclone Charlotte weakened gradually northwest of Australia. At 11:00 a.m. EDT on Wednesday the center of Tropical Cyclone Charlotte was located at latitude 20.4°S and longitude 107.6°E which put it about 430 miles (695 km) west-northwest of Learmonth, Australia. Charlotte was moving toward the south-southwest at 13 m.p.h (20 km/h). The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h). The minimum surface pressure was 979 mb.

Tropical Cyclone Charlotte Spins Northwest of Australia

Tropical Cyclone Charotte was spinning over the South Indian Ocean northwest of Australia on Tuesday night. At 11:00 p.m. EDT on Tuesday the center of Tropical Cyclone Charlotte was located at latitude 18.5°S and longitude 108.7°E which put it about 435 miles (700 km) northwest of Learmonth, Australia. Charlotte was moving toward the south-southwest at 6 m.p.h (10 km/h). The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 105 m.p.h. (165 km/h). The minimum surface pressure was 973 mb.

Tropical Cyclone Charlotte continued to spin over over the South Indian Ocean northwest of Australia on Tuesday night. The environment around Charlotte became less favorable for a tropical cyclone on Tuesday evening and the tropical cyclone was beginning to be affected the different environment. The ring of thunderstorms around the eye weakened and the overall distribution of thunderstorms became asymmetrical. The strongest thunderstorms were occurring in bands in the southern half of the circulation around Tropical Cyclone Charlotte. Bands in the northern half of the tropical cyclone consisted primarily of showers and lower clouds. Storms near the center of circulation were still generating upper level divergence that pumped mass away to the southeast of the tropical cyclone. Winds to tropical storm force extended out 125 miles (200 km) from the center of Tropical Cyclone Charlotte.

Tropical Cyclone Charlotte will continue to be in an environment unfavorable for a tropical cyclone during the next several days. Charlotte will move over water where the Sea Surface Temperatures are near 28˚C. An upper level trough over the South Indian Ocean will approach Charlotte from the west. The trough will produce northwesterly winds that will blow toward the top of Charlotte’s circulation. Those winds will cause moderate vertical wind shear. The flow of air around Tropical Cyclone Charlotte could also pull drier air into the western and northern parts of the circulation. The wind shear and the drier air will cause Tropical Cyclone Charlotte to weaken during the next several days.

Tropical Cyclone Charlotte will move around the western part of a high pressure system over Australia during the next 36 hours. The high pressure system will steer Charlotte toward the south. On its anticipated track Tropical Cyclone Charlotte will move parallel to the coast of Western Australia. Charlotte will remain west of the coast during the next 36 hours.

Tropical Cyclone Charlotte Strengthens to Equivalent of Hurricane/Typhoon

Tropical Cyclone Charlotte strengthened to the equivalent of a hurricane/typhoon over the South Indian Ocean northwest of Australia on Monday afternoon. At 5:00 p.m. EDT on Monday the center of Tropical Cyclone Charlotte was located at latitude 16.4°S and longitude 109.6°E which put it about 500 miles (805 km) northwest of Learmonth, Australia. Charlotte was moving toward the southwest at 9 m.p.h (15 km/h). The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 105 m.p.h. (165 km/h). The minimum surface pressure was 973 mb.

Tropical Cyclone Charlotte continued to intensify on Monday. A small circular eye formed at the center of Charlotte’s circulation. 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 small core of Tropical Cyclone Charlotte. Storms near the core generated upper level divergence that pumped mass away from the tropical cyclone. Winds to hurricane/typhoon force extended out 15 miles (25 km) from the center of circulation. Winds to tropical storm force extended out 140 miles (225 km) from the center.

Tropical Cyclone Charlotte will move through an environment favorable for intensification during the next 24 hours. Charlotte will move over water where the Sea Surface Temperatures are near 29˚C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Tropical Cyclone Charlotte is likely to continue to intensify during the next 24 hours. An upper level trough over the South Indian Ocean will approach Charlotte from the west in a day or so. The trough will produce northwesterly winds and those winds will cause the vertical wind shear to increase. Tropical Cyclone Charlotte will start to weaken when the wind shear increases.

Tropical Cyclone Charlotte will move around the northwestern part of a high pressure system over Australia during the next 24 hours. The high pressure system will steer Charlotte toward the southwest. On its anticipated track Tropical Cyclone Charlotte will move parallel to the coast of Western Australia during the next 24 hours. Charlotte will remain far away from the coast during the next several days.

Tropical Cyclone Charlotte Develops Quickly Northwest of Australia

Tropical Cyclone Charlotte developed quickly over the South Indian Ocean northwest of Australia on Sunday. At 11:00 p.m. EDT on Sunday the center of Tropical Cyclone Charlotte was located at latitude 14.9°S and longitude 111.5°E which put it about 550 miles (890 km) north-northwest of Learmonth,, Australia. Charlotte was moving toward the southwest at 15 m.p.h (24 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 985 mb.

A low pressure system over the South Indian Ocean northwest of Australia strengthened quickly on Sunday and the Australia Bureau of Meteorology designated the system as Tropical Cyclone Charlotte. The circulation around Tropical Cyclone Charlotte organized rapidly. The inner end of a rainband wrapped around the southern and western sides of the center of circulation and an eye appeared to be forming. Bands of showers and thunderstorms were revolving around the core of Charlotte’s circulation. Storms near the core generated upper level divergence that pumped mass away from the tropical cyclone. Winds to tropical storm force extended out 140 miles (225 km) from the center of circulation.

Tropical Cyclone Charlotte will move through an environment favorable for intensification during the next 24 hours. Charlotte will move over water where the Sea Surface Temperatures are near 30˚C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Tropical Cyclone Charlotte is likely to continue to intensify rapidly during the next 24 hours. Charlotte is likely to strengthen to the equivalent of a hurricane/typhoon during the next 12 hours.

Tropical Cyclone Charlotte will move around the northwestern part of a high pressure system over Australia during the next 24 hours. The high pressure system will steer Charlotte toward the west-southwest. On its anticipated track Tropical Cyclone Charlotte will move parallel to the coast of Western Australia during the next 24 hours. Charlotte will remain well away from the coast on Monday.

Tropical Cyclone Billy Passes South of Cocos Island

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 Storm Billy Strengthens South-southeast of 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.