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Tropical Cyclone Habana Develops South of Diego Garcia

Tropical Cyclone Habana developed over the South Indian Ocean south of Diego Garcia on Thursday. At 10:00 a.m. EST on Thursday the center of Tropical Cyclone Habana was located at latitude 16.5°S and longitude 73.0°E which put it about 640 miles (1035 km) south of Diego Garcia. Habana was moving toward the east-southeast at 14 m.p.h. (22 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 1000 mb.

An area of low pressure over the South Indian Ocean south of Diego Garcia strengthened on Thursday and the system was designated as Tropical Cyclone Habana. The circulation around Habana was still organizing. A primary rainband wrapped around the eastern and southern sides of the center of circulation. Other bands of showers and thunderstorms were developing. Storms near the center of circulation began to generate upper level divergence which pumped mass away from the tropical cyclone. Winds to tropical storm force extended out 115 miles (185 km) on the eastern side of Tropical Cyclone Habana. Winds to tropical storm force extended out 65 miles (105 km) in the western half of Habana.

Tropical Cyclone Habana will move through an environment favorable for intensification during the next 48 hours. Habana will move over water where the Sea Surface Temperatures will be near 29°C. It will move near the southern part of an upper level ridge. The ridge will produce westerly winds which will blow toward the top of Habana. Those winds will cause some vertical wind shear and the shear will limit the rate at which Tropical Cyclone Habana intensifies.

Tropical Cyclone Habana will move south of a high pressure system over the tropical South Indian Ocean. The high will steer Habana toward the east during the next several days. On its anticipated track Tropical Cyclone Habana will remain far to the south of Diego Garcia.

Elsewhere over the South Indian Ocean Tropical Cyclone Marian was weakening gradually. At 10:00 a.m. EST on Thursday the center of Tropical Cyclone Marian was located at latitude 22.1°S and longitude 94.1°E which put it about 680 miles (1100 km) south-southwest of Cocos Island. Marian was moving toward the south-southeast at 9 m.p.h. (15 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 991 mb.

Tropical Cyclone Marian Spins Southwest of Cocos Island

Tropical Cyclone Marian continued to spin over the South Indian Ocean southwest of Cocos Island on Tuesday. At 10:00 a.m. EST on Tuesday the center of Tropical Cyclone Marian was located at latitude 18.8°S and longitude 90.0°E which put it about 650 miles (1045 km) southwest of Cocos Island. Marian was moving toward the east-southeast at 3 m.p.h. (5 km/h). The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (200 km/h). The minimum surface pressure was 958 mb.

The circulation around Tropical Cyclone Marian remained well organized on Tuesday morning. A circular eye with a diameter of 35 miles (55 km) was present at the center of Marian. The eye was surrounded a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Even though the circulation was well organized, satellite images of Tropical Cyclone Marian suggested that it could be starting to weaken. The temperature of the tops of thunderstorms was warming which indicated that those storms were not rising as high in the atmosphere. Microwave satellite imagery depicted breaks forming in the southwestern part of the eyewall of Marian.

Winds to hurricane/typhoon force extended out 65 miles (105 km) from the center of Tropical Cyclone 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 17.8. The Hurricane Size Index (HSI) was 21.6 and the Hurricane Wind Intensity Size Index (HWISI) was 39.4.

Tropical Cyclone Marian will move into an environment that will be less favorable for tropical cyclones during the next few days. Marian will move over water where the Sea Surface Temperatures will be near 27°C. An upper level trough over the South Indian Ocean will approach Tropical Cyclone Marian from the west. The trough will produce northwesterly winds which will blow toward the top of Marian. Those winds will cause more vertical wind shear. A combination of slightly cooler water and more vertical wind shear will cause Tropical Cyclone Marian to weaken during the next several days.

The upper level trough will begin to steer Tropical Cyclone Marian toward the southeast. On its anticipated track Marian will move farther away from Cocos Island. Tropical Cyclone Marian is forecast to remain west of Western Australia during the next five days.

Tropical Cyclone Marian Intensifies To Equivalent of Major Hurricane

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..

Tropical Cyclone Marian Intensifies to Equivalent of Hurricane/Typhoon

Tropical Cyclone Marian intensified to the equivalent of a hurricane/typhoon over the South Indian Ocean southwest of Cocos Island on Saturday. At 10:00 a.m. EST on Saturday the center of Tropical Cyclone Marian was located at latitude 16.4°S and longitude 93.0°E which put it about 370 miles (595 km) southwest of Cocos Island. Marian was moving toward the southwest at 12 m.p.h. (19 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 976 mb.

Tropical Cyclone Marian continued to exhibit more organization on Saturday. An eye was visible at the center of Marian at times on satellite images. 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 Marian. Storms near the core generated upper level divergence which pumped mass away from the tropical cyclone. Winds to hurricane/typhoon force extended out 30 miles (50 km) from the center of Marian. Winds to tropical storm force extended out 185 miles (295 km) from the center of circulation.

Tropical Cyclone Marian will move through an environment favorable for intensification during the next 24 hours. Marian will move over water where the Sea Surface Temperatures will be near 29°C. It will move under the western portion of an upper level ridge. The upper level winds will be weak during the next 24 hours and there will not be a lot of vertical wind shear. Tropical Cyclone Marian is likely to continue to intensify during the next 24 hours.

Tropical Cyclone Marian will move around the western part of a subtropical high pressure system. The high will steer Marian toward the southwest during the next 36 hours. On its anticipated track Tropical Cyclone Marian will move farther away from Cocos Island. Marian could recurve back toward Australia next week after it moves around the western end of the high pressure system.

Tropical Cyclone Marian Strengthens South of Cocos Island

Tropical Cyclone Marian strengthened south of Cocos Island on Friday. At 10:00 a.m. EST on Friday the center of Tropical Cyclone Marian was located at latitude 14.9°S and longitude 96.4°E which put it about 190 miles (310 km) south of Cocos Island. Marian was moving toward the west at 17 m.p.h. (28 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 979 mb.

The circulation around an area of low pressure over the South Indian Ocean south of Cocos Island exhibited much more organization on Friday and the Australian Bureau of Meteorology designated the system as Tropical Cyclone Marian. Marian organized quickly during the past few hours. An eye was beginning to appear at the center of Marian on infrared satellite images. The inner end of a rainband was wrapping around the eye and the strongest winds were occurring in the developing eyewall. Thunderstorms near the center of Marian generated upper level divergence that pumped mass away from the tropical cyclone. Winds to tropical storm force extended out 200 miles (320 km) in the southern half of Tropical Cyclone Marian. Winds to tropical storm force extended out 120 miles (195 km) in the northern half of Marian.

Tropical Cyclone Marian will move through an environment favorable for intensification during the next 36 hours. Marian will move over water where the Sea Surface Temperatures will be near 29°C. It will move under the northern portion of an upper level ridge. The ridge will produce easterly winds which will blow toward the top of the circulation. However, the winds speeds will be similar at different levels in the atmosphere and there will not be a lot of vertical wind shear. Tropical Cyclone Marian will intensify into the equivalent of a hurricane/typhoon during the next 24 hours.

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

Tropical Cyclone Herold Brings Wind, Rain to Rodrigues

Tropical Cyclone Herold brought wind and rain to Rodrigues on Tuesday.  At 5:00 p.m. EDT on Tuesday the center of Tropical Cyclone Herold was located at latitude 21.4°S and longitude 64.1°E which put it about 125 miles (200 km) south-southeast of Port Mathurin, Mauritius.  Herold was moving toward the southeast at 21 m.p.h. (34 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 978 mb.

The core of Tropical Cyclone Herold passed west of Rodrigues on Tuesday, but it came close enough to that island to bring gusty winds and locally heavy rain.  A weather station at the Plaine Corail airport on Rodrigues reported a wind gust of 80 m.p.h. (130 km/h).

Although Tropical Cyclone Herold began to weaken on Tuesday.  It remained strong enough to generate wind gusts to hurricane/typhoon force over parts of Rodrigues.  Microwave satellite imagery indicated the there was still an eye at the center of Herold, although the eye was not evident on conventional infrared images.  The eye was surround by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Winds to hurricane/typhoon force extended out 50 miles (80 km) from the center of circulation.  Winds to tropical storm force extended out about 150 miles (240 km) from the center.

Tropical Cyclone Herold will continue to weaken during the next several days.  An upper level trough near Madagascar and an upper level ridge over the South Indian Ocean will interact to produce strong northwesterly winds which will blow toward the top of Herold.  Those winds will cause strong vertical wind shear and they will cause the tropical cyclone to weaken.

The upper level trough and ridge will steer Tropical Cyclone Herold toward the southeast.  On its anticipated track Herold will move quickly away from Rodrigues.  Weather conditions on that island will gradually improve as Tropical Cyclone Herold moves farther away.

Tropical Cyclone Herold Passes North of Mauritius

Tropical Cyclone Herold passed north of Mauritius on Monday.  At 5:00 p.m. EDT on Monday the center of Tropical Cyclone Herold was located at latitude 17.3°S and longitude 57.6°E which put it about 230 miles (370 km) north of Port Louis, Mauritius.  Herold was moving toward the east-southeast at 20 m.p.h. (32 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 972 mb.

The circulation around Tropical Cyclone Herold remained well organized on Monday.  Microwave satellite imagery indicated that there was an eye at the center of circulation, but the eye was not visible on conventional satellite images.  The eye was surround by a narrow 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 Herold.  Many of the stronger thunderstorms were in bands south and east of the center of circulation.  Winds to hurricane/typhoon force extended out 35 miles (55 km) from the center.  Winds to tropical storm force extended out 130 miles (215 km) from the center of circulation.

Tropical Cyclone Herold may have reached its maximum intensity.  Herold will move over water where the Sea Surface Temperature is near 28°C.  So, there will be plenty of energy in the upper layer of the South Indian Ocean to support intensification.  However, an upper level trough near Madagascar and an upper level ridge over the South Indian Ocean will interact to produce strong northwesterly winds which will blow toward the top of Tropical Cyclone Herold.  Those winds will cause moderate vertical wind shear and they will likely prevent further intensification.  In fact the wind shear is likely to be strong enough to cause Herold to start to weaken during the next 24 hours.

The upper level trough and ridge will combine to steer Tropical Cyclone Herold quickly toward the east-southeast.  On its anticipated track Herold could reach Rodrigues within 24 hours.  Tropical Cyclone Herold is likely to bring gusty winds and locally heavy rain to Port Mathurin and the rest of Rodrigues.  Heavy rain could cause flash floods in some locations.

Tropical Cyclone Gretel Speeds By New Caledonia

Tropical Cyclone Gretel sped by New Caledonia on Sunday.  At 5:00 p.m. EDT on Sunday the center of Tropical Cyclone Gretel was located at latitude 25.9°S and longitude 169.4°E which put it about 750 miles (1210 km) north-northwest of Auckland, New Zealand.  Gretel was moving toward the southeast at 37 m.p.h. (60 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 983 mb.

Tropical Cyclone Gretel moved around the western end of high pressure system over the South Pacific Ocean.  The high steered Gretel rapidly toward the southeast and the tropical cyclone sped over the Coral Sea west of New Caledonia.  Rainbands on the eastern side of Tropical Cyclone Gretel brought wind and rain to portions of New Caledonia on Sunday.

An upper level ridge produced strong northwesterly winds which created strong vertical wind shear.  The wind shear tilted the circulation around Tropical Cyclone Gretel toward the southeast and Gretel began to weaken.  The stronger thunderstorms were occurring in bands south and east of the center of Gretel.  Bands in other parts of the tropical cyclone consisted primarily of showers and lower clouds.  The wind field around Gretel expanded when the tropical cyclone started to weaken.  Winds to tropical storm force extended out 250 miles (400 km) from the center of circulation.

Tropical Cyclone Gretel will continue to move rapidly toward the southeast during the next several days.  On its anticipated track Gretel could pass north of New Zealand in 24 to 36 hours.

Elsewhere, over the South Indian Ocean Tropical Cyclone Herold strengthened east of Madagascar.  At 5:00 p.m EDT on Sunday the center of Tropical Cyclone Herold was located at latitude 15.5°S and longitude 53.2°E which put it about 405 miles (655 km) west-northwest of Port Louis, Mauritius.  Herold was moving toward the east-southeast at 7 m.p.h. (11 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 972 mb.  Tropical Cyclone Herold could reach Rodrigues in about 48 hours.

Tropical Cyclone Herold Drops Heavy Rain Over Northeast Madagascar

Tropical Cyclone Herold dropped heavy rain over parts of northeast Madagascar on Saturday.  A rainband on the western side of Herold was dropping locally heavy rain over northern Madagascar from Mananara to Iharana.  At 5:00 p.m. EST on Saturday the center of Tropical Cyclone Herold was located at latitude 15.0°S and longitude 51.2°E which put it about 545 miles (880 km) northwest of Port Louis, Mauritius.  Herold was moving toward the east at 1 m.p.h. (2 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 Herold strengthened into the equivalent of a hurricane/typhoon on Saturday.  A large ragged circular eye with a diameter of 50 miles (80 km) formed at the center of Herold.  A broken ring of thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms.  One strong band of showers and thunderstorms wrapped around the eastern and southern sides of Tropical Cyclone Herold.  A second strong band of showers and thunderstorms wrapped around the western and northern sides of Herold.  Winds to hurricane/typhoon force extended out 25 miles (40 km) from the center of circulation.  Winds to tropical storm force extended out 85 miles from the center.

Tropical Cyclone Herold will move through an environment favorable for intensification during the next 48 hours.  Herold will move over water where the Sea Surface Temperature is near 29°C.  It will move under an upper level ridge where the winds are weak and there will be little vertical wind shear.  Tropical Cyclone Herold will intensify during the next 48 hours and it could strengthen into the equivalent of a major hurricane.

Tropical Cyclone Herold has been in an area where the steering winds are weak and it has not moved very far during the past 24 hours.  A subtropical high pressure system over the South Indian Ocean will strengthen.  Herold will move around the southwestern part of the high pressure system and the high will steer the tropical cyclone toward the east-southeast.  On its anticipated track Tropical Cyclone Herold will move away from Madagascar on Sunday.  The center of Herold could pass north of Mauritius in three days.  Tropical Cyclone Herold could approach Rodrigues in 84 to 90 hours.

Tropical Cyclone Herold Forms East of Madagascar

Tropical Cyclone Herold formed over the South Indian Ocean east of Madagascar on Friday.  At 5:00 p.m. EDT on Friday the center of Tropical Cyclone Herold was located at latitude 14.8°S and longitude 51.9°E which put it about 510 miles (825 km) northwest of Port Louis, Mauritius.  Herold was moving toward the southwest at 4 m.p.h. (6 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.

A distinct low level center of circulation organized quickly in an area of thunderstorms east of Madagascar on Friday and the system was designated as Tropical Cyclone Herold.  The circulation around Herold was still organizing and the distribution of thunderstorms was asymmetrical.  Many of the stronger thunderstorms developed in bands northwest of the center of circulation.  Bands in other parts of the circulation consisted primarily of showers and lower clouds.  Thunderstorms northwest of the center of Herold were generating upper level divergence which was pumping mass away from the tropical cyclone.  Winds to tropical storm force extended out 85 miles (135 km) from the center of circulation.

Tropical Cyclone Herold will move through an environment that will become increasingly favorable for intensification during the next several days.  Herold is currently under a small upper level ridge centered near Madagascar.  The ridge is producing southeasterly winds which are blowing toward the top of the circulation.  Those winds are causing some vertical wind shear and they are probably the reason for the asymmetrical distribution of thunderstorms.  However, Tropical Cyclone Herold will move into a region where the upper level winds are weaker during the weekend.  Herold will move over water where the Sea Surface Temperature is near 29°C during that time period.  Tropical Cyclone Herold will intensify during the next several days and it could intensify rapidly once the inner core becomes better organized.  Herold is likely to intensify into the equivalent of a hurricane/typhoon during the next 24 hours.  It could strengthen into the equivalent of a major hurricane during the next 72 hours.

Tropical Cyclone Herold is currently in an area where the steering currents are weak.  A subtropical high pressure system over the South Indian Ocean will strengthen during the next several days.  The western end of the subtropical high will start to steer Herold toward the east-southeast during the weekend.  On its anticipated track the center of Tropical Cyclone Herold could be northwest of Mauritius in less than 72 hours.  Herold is likely to be the equivalent of a major hurricane at that time.