Category Archives: Indian Ocean

Major Tropical Cyclone Harold Nears Vanuatu

Major Tropical Cyclone Harold neared Vanuatu on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Tropical Cyclone Vanuatu was located at latitude 15.5°S and longitude 166.0°E which put it about 80 miles (130 km) west-northwest of Unmet, Vanuatu.  Harold was moving toward the southeast at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 150 m.p.h. (240 km/h).  The minimum surface pressure was 949 mb.

Tropical Cyclone Harold intensified into the equivalent of a major hurricane.  The original small eye dissipated but a new larger eye developed on Saturday night.  The new eye was surround 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 Harold.  The strongest rainbands were in the eastern and southern parts of the circulation.  Storms near the core of Harold generated upper level divergence which pumped mass away from the center of the tropical cyclone.

Winds to hurricane/typhoon force extended out 30 miles (50 km) from the center of Tropical Cyclone Harold.  Winds to tropical storm force extended out 125 miles (200 km) from the center of circulation.  The Hurricane Intensity Index (HII) for Harold was 22.1.  The Hurricane Size Index (HSI) was 11.1 and the Hurricane Wind Intensity Size Index (HWISI) was 33.2.  Tropical Cyclone Harold was capable of causing major damage.

Tropical Cyclone Harold will move through an environment favorable for intensification during the next 24 hours.  Harold will move over water where the Sea Surface Temperature is near 30°C.  It will move around the southwestern part of an upper level ridge over the South Pacific Ocean.  The ridge will produce northwesterly winds which will blow toward the top of the circulation.  Those winds will cause some vertical wind shear and the wind shear could be strong enough to limit intensification.  Tropical Cyclone Harold could intensify further, but it may maintain its intensity on Sunday.

The ridge over the South Pacific Ocean will steer Tropical Cyclone Harold slowly toward the southeast during the next 24 hours.  On its anticipated track the core of Harold with the strongest winds will move slowly toward Malekula.  Tropical Cyclone Harold will drop heavy rain over central Vanuatu.  The slow movement of Harold could create the potential for very serious flooding on Espiritu Santo, Malekula, Ambrym and Epi.

Elsewhere in the tropics, Tropical Cyclone Irondro began to slowly weaken over the South Indian Ocean.  At 5:00 p.m. EDT on Saturday the center of Tropical Cyclone Irondro was located at latitude 23.3°S and longitude 81.5°E which put it about 1275 miles (2060 km) southwest of Cocos Island.  Irondro was moving toward the southeast at 18 m.p.h. (29 km/h).  The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 130 m.p.h. (210 km/h).  The minimum surface pressure was 958 mb.

Tropical Cyclone Harold Rapidly Intensifies into Equivalent of Hurricane/Typhoon

Tropical Cyclone Harold rapidly intensified into the equivalent of a hurricane/typhoon west-northwest of Vanuatu on Friday.  At 11:00 p.m. EDT on Friday the center of Tropical Cyclone Harold was located at latitude 14.1°S and longitude 164.1°E which put it about 170 miles (275 km) west-northwest of Nokuku, Vanuatu.  Harold was moving toward the southeast at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 105 m.p.h. (170 km/h) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 959 mb.

The circulation around Tropical Cyclone Harold organized quickly on Friday.  The inner end of a rainband wrapped around the center of circulation and a small eye formed.  A ring of strong thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Harold.  The strongest rainbands were in the eastern half of the circulation.  Bands in the western half of the circulation consisted primarily of showers and lower clouds.  Storms around the core of the circulation generated strong upper level divergence which pumped mass away to the east of the tropical cyclone.

Winds to hurricane/typhoon force extend out 35 miles (55 km) from the center of Tropical Cyclone Harold.  Winds to tropical storm force extended out 140 miles (225 km) from the center of circulation.  The Hurricane Intensity Index (HII) for Tropical Cyclone Harold was 17.8.  The Hurricane Size Index (HSI) was 12.0 and the Hurricane Wind Intensity Size Index (HWISI) was 29.8.  Harold was capable of causing serious damage.

Tropical Cyclone Harold will move through an environment favorable for intensification during the next 24 to 48 hours.  Harold will move over water where the Sea Surface Temperature is near 30°C.  It will move around the southwestern part of an upper level ridge over the South Pacific Ocean.  The ridge will produce northwesterly winds which will blow toward the top of the circulation.  Those winds will cause some vertical wind shear, but the shear will not be strong enough to prevent intensification.  Tropical Cyclone Harold will strengthen into the equivalent of a major hurricane during the next 12 hours.

The upper level ridge will steer Tropical Cyclone Harold slowly toward the southeast during the weekend.  On its anticipated track Harold will gradually approach Espiritu Santo and Malekula in Vanuatu.  The core of Tropical Cyclone Harold could move across the central part of Vanuatu in 48 to 72 hours.  Harold is likely to be the equivalent of a major hurricane at that time.

Elsewhere in the tropics, Tropical Cyclone Irondro intensified into the equivalent of a hurricane/typhoon over the South Indian Ocean.  At 5:00 p.m. EDT on Friday the center of Tropical Cyclone Irondro was located at latitude 19.9°S and longitude 76.4°E which put it about 885 miles (1425 km) south-southeast of Diego Garcia.  Irondro was moving toward the east-southeast at 21 m.p.h. (33 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. (170 km/h).  The minimum surface pressure was 973 mb.

Tropical Cyclone Irondro Forms South-southwest of Diego Garcia

Tropical Cyclone Irondro formed south-southwest of Diego Garcia on Thursday.  At 5:00 a.m. EDT on Thursday the center of Tropical Cyclone Irondro was located at latitude 13.5°S and longitude 69.9°E which put it about 460 miles (745 km) south-southwest of Diego Garcia.  Irondro was moving toward the southeast at 5 m.p.h. (8 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.

A distinct low level center of circulation developed in an area of thunderstorms over the South Indian Ocean south-southwest of Diego Garcia on Thursday and the system was designated as Tropical Cyclone Irondro.  The circulation around Irondro was still organizing.  Bands of showers and thunderstorms were forming and the bands were beginning to revolve around the center of circulation.  Storms near the center were generating upper level divergence which was pumping mass away from the tropical cyclone.  Winds to tropical storm force extended out 145 miles (230 km) from the center of circulation.

Tropical Cyclone Irondro will move through an environment favorable for intensification during the next 48 to 60 hours.  Irondro will move over water where the Sea Surface Temperature is near 28°C.  It will move under the western end of an upper level high over the South Indian Ocean.  The high will produce northwesterly winds which will blow toward the top of the tropical cyclone.  Those winds will cause some vertical wind shear, but the shear will not be strong enough to prevent intensification.  Tropical Cyclone Irondro will intensify and it could strengthen into the equivalent of a hurricane/typhoon.

The upper level high and an upper level trough east of Madagascar will interact to steer Tropical Cyclone Irondro toward the southeast during the next few days.  On its anticipated track Irondro will pass south of Diego Garcia and south of 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.

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 Esther Makes Landfall in Northern Australia

Tropical Cyclone Esther made landfall in northern Australia just to the east of the border between Queensland and the Northern Territory on Sunday night.  At 10:00 p.m. EST on Sunday the center of Tropical Cyclone Esther was located at latitude 16.7°S and longitude 137.9°E which put it about 65 miles (105 km) west of Mornington Island.  Esther was moving toward the west-southwest at 10 m.p.h. (16 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 988 mb.

A Warning remained in effect for the portion of the coast from Port McArthur to Karumba, Australia including Borroloola and Mornington Island.

Tropical Cyclone Esther was intensifying slowly when it made landfall just east of the border between Queensland and the Northern Territory of Australia.  Winds to tropical storm force extended out 75 miles (120 km) from the center of circulation.  A weather station at Mornington Island reported a sustained wind speed of 35 m.p.h. (57 km/h) and a wind gust of 54 m.p.h. (87 km/h).  The station measured 6.77 inches (172 mm) of rain.

Tropical Cyclone Esther will weaken as it moves inland.  Esther will move north of a high pressure system over Australia.  The high will steer Tropical Cyclone Esther toward the west during the next few days.  On its anticipated track Esther will move across the Northern Territory.  Tropical Cyclone Esther will drop locally heavy rain and it could cause flash floods in some locations.  There is a potential for Esther to strengthen again in a few days when it moves over the South Indian Ocean northwest of Australia.

Elsewhere, Tropical Cyclone Ferdinand developed over the South Indian Ocean northwest of Australia.  At 4:00 p.m. EST on Sunday the center of Tropical Storm Ferdinand was located at latitude 13.8°S and longitude 117.8°E which put it about 450 miles (750 km) north of Port Hedland, Australia.  Ferdinand was moving toward the southwest 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 993 mb.  Tropical Cyclone Ferdinand is forecast to move toward the west-southwest and to strengthen into the equivalent of a hurricane/typhoon.