Tag Archives: 20S

Tropical Cyclone Bianca Weakens Rapidly

Tropical Cyclone Bianca weakened rapidly over the South Indian Ocean west of Australia on Wednesday.  At 4:00 a.m. EST on Wednesday the center of Tropical Cyclone Bianca was located at latitude 25.7°S and longitude 102.7°E which put the center about 730 miles (1175 km) west of Carnarvon, Australia.  Bianca was moving toward the south-southeast at 7 m.p.h. (11 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 999 mb.

Tropical Cyclone Bianca weakened rapidly over the South Indian Ocean west of Australia on Wednesday.  An upper level trough west of Australia produced strong northwesterly winds that blew across the top of Tropical Cyclone Bianca.  Those winds caused strong vertical wind shear.  The vertical wind shear blew the upper part of Bianca’s circulation to the southeast of the circulation in the lower levels.

The circulation of Tropical Cyclone Bianca consisted of bands of showers and lower clouds that were revolving around the low level center of circulation.  Strong vertical wind shear was blowing the tops off of clouds that rose higher into the atmosphere.

The circulation around Tropical Cyclone Bianca was small.  Winds to tropical storm force extended out 100 miles (160 km) from the center of Bianca’s circulation.

Tropical Cyclone Bianca will move through an environment that will be unfavorable for intensification during the next 24 hours.  Bianca will move over water where where the Sea Surface Temperatures are near 23°C.  It will move under the eastern side of an upper level trough over the South Indian Ocean.  The upper level trough will continue to produce strong northwesterly winds that will blow across the top of Bianca’s circulation.  Those winds will cause strong vertical wind shear.  Cooler water and strong vertical wind shear will cause Tropical Cyclone Bianca to continue to weaken during the next 24 hours.

Since the circulation around Tropical Cyclone Bianca exists only in the lower levels of the atmosphere, Bianca will be steered by the weather features near the surface.  Bianca will move around the northern side of a high pressure system over the South Indian Ocean.  The high pressure system will steer Bianca toward the west during the next 24 hours.  On its anticipated track, Tropical Cyclone Bianca will move farther away from Western Australia.

Tropical Cyclone Bianca Strengthens to Equivalent of Major Hurricane

Tropical Cyclone Bianca strengthened to the equivalent of a major hurricane on Monday night.  At 4:00 a.m. EST on Tuesday the center of Tropical Cyclone Bianca was located at latitude 22.3°S and longitude 102.0°E which put the center about 765 miles (1235 km) west of the Exmouth, Australia.  Bianca was moving toward the south-southwest at 11 m.p.h. (17 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 962 mb.

Tropical Cyclone Bianca strengthened to the equivalent of a major hurricane over the South Indian Ocean west of Australia on Monday night.  A circular eye with a diameter of 20 miles (32 km) was at the center of Bianca’s circulation.  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 revolved around the center of Bianca’s circulation.  Storms near the center of Bianca generated upper level divergence that pumped mass away from the tropical cyclone.

The circulation around Tropical Cyclone Bianca was small.  Winds to hurricane/typhoon force extended out 25 miles (40 km) from the center of Bianca’s circulation.  Winds to tropical storm force extended out 100 miles (160 km) from the center of Tropical Cyclone Bianca.

The Hurricane Intensity Index (HII) for Tropical Cyclone Bianca was 20.6.  The Hurricane Size Index (HSI) was 9.3 and the Hurricane Wind Intensity Size Index (HWISI) was 29.9.

Tropical Cyclone Bianca will move into an environment that will become unfavorable for intensification during the next 24 hours.  Bianca will move over water where where the Sea Surface Temperatures are near 26°C.  It will move under the eastern side of an upper level trough over the South Indian Ocean.  The upper level trough will produce northwesterly winds that will blow toward the top of Bianca’s circulation.  Those winds will cause the vertical wind shear to increase.  Tropical Cyclone Bianca will weaken when the vertical wind shear increases.

Tropical Cyclone Bianca will move around the western part of a high pressure system over the South Indian Ocean.  The high pressure system will steer Bianca toward the south during the next 24 hours.  On its anticipated track, Tropical Cyclone Bianca will move parallel to the coast of Western Australia.

Tropical Cyclone Bianca Strengthens to Equivalent of Hurricane/Typhoon

Tropical Cyclone Bianca strengthened to the equivalent of a hurricane/typhoon over the South Indian Ocean on Sunday night.  At 4:00 a.m. EST on Monday the center of Tropical Cyclone Bianca was located at latitude 19.3°S and longitude 103.3°E which put the center about 645 miles (1040 km) southeast of the Cocos Islands.  Bianca was moving toward the southwest at 13 m.p.h. (21 km/h).  The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 985 mb.

Tropical Cyclone Bianca rapidly intensified to the equivalent of a hurricane/typhoon over the South Indian Ocean southeast of the Cocos Islands during Sunday night.  The inner end of a rainband wrapped around the center of Bianca’s circulation.  A circular eye formed at the center of Tropical Cyclone Bianca.  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 revolved around the center of Bianca’s circulation.  Storms near the center of Bianca generated upper level divergence that pumped mass away from the tropical cyclone.  The removal of mass caused the surface pressure to decrease.

The circulation around Tropical Cyclone Bianca was small.  Winds to hurricane/typhoon force extended out 20 miles (3o km) from the center of Bianca’s circulation.  Winds to tropical storm force extended out 75 miles (120 km) from the center of Tropical Cyclone Bianca.

Tropical Cyclone Bianca will move through an environment favorable for intensification during the next 24 hours.  Bianca will move over water where where the Sea Surface Temperatures are near 27°C.  It will move under the middle of an upper level ridge over the South Indian Ocean.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Tropical Cyclone Bianca is likely to continue to intensify during the next 24 hours.

Tropical Cyclone Bianca will move around the northwestern part of a high pressure system over the South Indian Ocean.  The high pressure system will steer Bianca toward the southwest during the next 24 hours.  On its anticipated track, Tropical Cyclone Bianca will remain far to the southeast of the Cocos Islands.

Tropical Cyclone Alfred Forms over the Coral Sea

Tropical Cyclone Alfred formed over the Coral Sea on Sunday.  At 4:00 a.m. EST on Sunday the center of Tropical Cyclone Alfred was located at latitude 14.3°S and longitude 153.7°E which put the center about 560 miles (900 km) east-northeast of Cairns, Australia.  Alfred was moving toward the east at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 990 mb.

A low pressure system over the Coral Sea strengthened on Sunday and the Australian Bureau of Meteorology designated the system as Tropical Cyclone Alfred.  The circulation around Tropical Cyclone Alfred exhibited more organization on Sunday.  More thunderstorms formed near the center of Alfred’s circulation.  More thunderstorms also developed in bands revolving around the center of Tropical Cyclone Alfred.  Storms near the center of Alfred generated upper level divergence that pumped mass away from the tropical cyclone.  The removal of mass caused the surface pressure to decrease.

The circulation around Tropical Cyclone Alfred was fairly large.  Winds to tropical storm force extended out 180 miles (290 km) from the center of Alfred’s circulation.

Tropical Cyclone Alfred will move through an environment favorable for intensification during the next 24 hours.  Alfred will move over water where where the Sea Surface Temperatures are near 29°C.  It will move under the middle of an upper level ridge over the Coral Sea.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Tropical Cyclone Alfred will intensify during the next 24 hours.

Tropical Cyclone Alfred will move around the southern side of a high pressure system that is near the Equator.  The high pressure system will steer Alfred toward the east during the next 24 hours.  On its anticipated track, Tropical Cyclone Alfred will move farther away from Australia.  Alfred is like to start to move toward the south early next week.

Elsewhere, Tropical Cyclone Bianca formed over the South Indian Ocean northwest of Australia.  At 4:00 a.m. EST on Sunday the center of Tropical Cyclone Bianca was located at latitude 17.0°S and longitude 106.9°E which put the center about 590 miles (950 km) northwest of Exmouth, Australia.  Bianca was moving toward the west-southwest at 15 m.p.h. (24 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 998 mb.

Tropical Cyclone Gamane Brings Wind and Rain to Northern Madagascar

Tropical Cyclone Gamane brought strong winds and heavy rain to northern Madagacar on Wednesday. At 11:00 a.m. EDT on Wednesday the center of Tropical Cyclone Gamane was located at latitude 13.5°S and longitude 49.1°E which put it about 25 miles (40 km) south of the Ambilobe, Madagascar. Gamane was moving toward the southwest at 6 m.p.h. (10 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 991 mb.

Tropical Cyclone Gamane rapidly intensified to the equivalent of a hurricane/typhoon before it made landfall on the coast of northern Madagascar near Iharana on Tuesday night. The circulation around Gamane was small at the time of landfall. Winds to hurricane/typhoon force extended out 25 miles (40 km) from the center of Tropical Cyclone Gamane at the time of landfall. Winds to tropical storm force only extended out 65 miles (105 km) from the center of Gamane’s circulation.

Tropical Cyclone Gamane weakened after the center of circulation moved over land. However, the circulation around Tropical Cyclone Gamane remained well organized. Thunderstorms were still occurring near the center of Gamane’s circulation. Bands of showers and thunderstorms were revolving around the center of circulation. Storms near the center of Gamane generated upper level divergence that pumped mass away from the tropical cyclone. Winds to tropical storm force extended out 65 miles (105 km) from the center of Tropical Cyclone Gamane.

Tropical Cyclone Gamane will move around the western end of a high pressure system over the South Indian Ocean. The high pressure system will steer Gamane toward the south during the next 24 hours. On its anticipated track, Tropical Cyclone Gamane will move toward the south over northern Madagascar. Gamane will continue to weaken while the center of circulation is over land. Even though Tropical Cyclone Gamane will weaken, it will continue to drop heavy rain over parts of northern Madagascar. Heavy rain will cause floods in some locations.

An upper level trough southwest of Madagascar will start to steer Tropical Cyclone Gamane toward the southeast in a day or so. The center of Gamane is likely to move back over the Southwest Indian Ocean on Friday. Tropical Cyclone Gamane could strengthen once the center of circulation moves back over water. Gamane could affect La Reunion and Mauritius during the weekend.

Tropical Cyclone Gamane Forms Near Northern Madagascar

Tropical Cyclone Gamane formed over the South Indian Ocean near northern Madagascar on Monday night. At 8:00 a.m. EDT on Tuesday the center of Tropical Cyclone Gamane was located at latitude 12.2°S and longitude 50.7°E which put it about 90 miles (145 km) east of the Antsiranana, Madagascar. Gamane was moving toward the northwest at 4 m.p.h. (6 km/h). The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h). The minimum surface pressure was 989 mb.

A low pressure system over the South Indian Ocean near northern Madagascar strengthened during Monday night and Meteo France La Reunion designated the system as Tropical Cyclone Gamane. The circulation around Tropical Cyclone Gamane was organizing quickly. Numerous thunderstorms formed near the center of Gamane’s circulation. Bands of showers and thunderstorms were revolving around the center of circulation. Storms near the center generated upper level divergence that pumped mass away from the tropical cyclone. Winds to tropical storm force extended out 85 miles (135 km) from the center of Tropical Cyclone Gamane.

Tropical Cyclone Gamane will move through an environment favorable for intensification during the next 24 hours. Gamane will move over water where the Sea Surface Temperatures are near 29°C. It will move under the axis of an upper level ridge over the Southwest Indian Ocean. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. Part of the circulation around the western side of Gamane will move over northern Madagascar, which is the only factor that could inhibit intensification. Tropical Cyclone Gamane will intensify during the next 24 hours. Gamane could intensify rapidly at times. Tropical Cyclone Gamane is likely to strengthen to the equivalent of a hurricane/typhoon, if the center of circulation remains over water.

Tropical Cyclone Gamane will move around the western side of a high pressure system over the South Indian Ocean. The high pressure system will steer Gamane slowly toward the south-southwest during the next 24 hours. On its anticipated track, the center of Tropical Cyclone Gamane will move close to the coast of northeastern Madagascar. The center of circulation could pass very close to Iharana, Sambava, Antalaha, and Ambohitralanana.

Tropical Cyclone Gamane will bring strong winds to the coast of northeastern Madagascar. Gamane will also drop heavy rain over parts of northeastern Madagascar. Tropical Cyclone Gamane will move slowly during the next 24 hours. So, prolonged heavy rain is likely to cause floods in some locations.

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.

Former Tropical Cyclone Esther Drops Heavy Rain Over Northwestern Australia

Former Tropical Cyclone Esther dropped heavy rain over parts of northwestern Australia on Wednesday.  At 10:00 p.m. EST on Wednesday the center of Tropical Cyclone Esther was located at latitude 15.3°S and longitude 130.8°E which put it about 240 miles (390 km) south of Darwin, Australia.  Esther was moving toward the west at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 996 mb.

The circulation around former Tropical Cyclone Esther remained very well organized on Wednesday even though it had been moving across northern Australia for several days.  There was a distinct low level center of circulation.  The circulation was surrounded by bands of showers and thunderstorms.  Strong thunderstorms developed south of Darwin in a band in the northern part of the circulation.  The Darwin harbor reported a wind gust of 44 m.p.h. (72 km/h).  The Wyndham airport reported a wind gust of 39 m.p.h. (63 km/h).

Former Tropical Cyclone Esther could strengthen back into a tropical cyclone if the center of circulation moves over the South Indian Ocean west of Australia.  Esther will move through an environment favorable for intensification during the next day or two.  The Sea Surface Temperature near the west coast of Australia is near 30°C.  Esther will move under an upper level ridge where the winds are weak and there is little vertical wind shear.  Former Tropical Cyclone Esther could intensify rapidly if the center of circulation moves completely over water.

Former Tropical Cyclone Esther will move around the western end of a high pressure system over Australia during the next several days.  The high will steer Esther toward the west during the next 24 to 48 hours.  It will turn more toward the south when it reaches the western end of the high pressure system.  On its anticipated track the center of former Tropical Cyclone Esther will pass near the southern end of the Joseph Bonaparte Gulf.

Elsewhere over the South Indian Ocean, Tropical Cyclone Ferdinand churned northwest of Australia.  At 10:00 p.m. EST the center of Tropical Cyclone Ferdinand was located at latitude 16.6°S and longitude 114.3°E which put it about 400 miles (645 km) north of Learmonth, Australia.  Ferdinand was moving toward the west at 3 m.p.h. (5 km/h).  The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 115 m.p.h. (185 km/h).  The minimum surface pressure was 966 mb.

Tropical Cyclone Ferdinand Strengthens to Equivalent of Hurricane/Typhoon

Tropical Cyclone Ferdinand strengthened to the equivalent of a hurricane/typhoon over the South Indian Ocean northwest of Australia on Monday night.  At 10:00 p.m. EST on Monday the center of Tropical Cyclone Ferdinand was located at latitude 15.4°S and longitude 117.0°E which put it about 520 miles (840 km) north-northeast of Learmonth, Australia.  Ferdinand was moving toward the southwest at 5 m.p.h. (8 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 975 mb.

The circulation around Tropical Cyclone Ferdinand exhibited much greater organization on Monday.  A very small circular eye formed at the center of circulation.  The eye was surrounded by a ring of strong thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms.  Storms around the eye generated upper level divergence which was pumping mass away form the tropical cyclone.  Bands of showers and thunderstorms were revolving around the core of Ferdinand.  Winds to hurricane/typhoon force extended out 25 miles (40 km) from the center of circulation.  Winds to tropical storm force extended out 70 miles (100 km) from the center.

Tropical Cyclone Ferdinand will move through an environment favorable for intensification during the next 24 to 36 hours.  Ferdinand will move over water where the Sea Surface Temperature is near 29°C.  It will move under an upper level ridge over the South Indian Ocean northwest of Australia.  The upper level winds will be weak and there will be little vertical wind shear.  Tropical Cyclone Ferdinand will continue intensify and it could strengthen to the equivalent of a major hurricane during the next 24 to 36 hours.

Tropical Cyclone Ferdinand will move north of a high pressure system over the South Indian Ocean.  The high will steer Ferdinand slowly toward the west-southwest during the next several days.  On its anticipated track Tropical Cyclone Ferdinand will remain well to the northwest of Western Australia.

Elsewhere, Tropical Cyclone Esther was moving westward over the Northern Territory of Australia.  At 10:00 p.m. EST on Monday the center of Tropical Cyclone Esther was located at latitude 17.3°S and longitude 135.4°E which put it about 125 miles (200 km) east of Newcastle Waters, Australia.  Esther was moving toward the west at 7 m.p.h. (11km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 997 mb.  Tropical Cyclone Esther was dropping locally heavy rain over parts of the Northern Territory.  A Flood Watch was in effect for the Coastal Carpentaria Rivers, Barkly and the Western Top End.