Tropical Cyclone Irene Forms West of Vanuatu

Tropical Cyclone Irene formed over the South Pacific Ocean west of Vanuatu on Wednesday morning. At 10:00 a.m. EST on Wednesday the center of Tropical Cyclone Irene was located at latitude 18.7°S and longitude 166.3°E which put it about 320 miles (520 km) west-southwest of Port Vila, Vanuatu. Irene was moving toward the east at 21 m.p.h. (33 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.

An area of low pressure over the South Pacific Ocean strengthened rapidly on Wednesday morning and the Fiji Meteorological Service designated the system as Tropical Cyclone Irene. The inner end of a rainband wrapped around the western and southern side of Irene’s circulation. Other bands of thunderstorms were occurring in the eastern half of Tropical Cyclone Irene. Bands in the western 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 to the southeast of the tropical cyclone. Winds to tropical storm force extended out 115 miles (185 km) from the center of Irene.

Tropical Cyclone Irene will move through an environment favorable for intensification during the next 24 hours. Irene will move over over water where the Sea Surface Temperatures are near than 28˚C. An upper level trough east of Australia will produce northwesterly winds that will blow toward the top of Irene’s circulation. Those winds will cause vertical wind shear, but the wind shear will not be strong enough to prevent intensification. Tropical Cyclone Irene is likely to intensify during the next 24 hours. It could intensify rapidly during the next 12 hours. Irene could strengthen to the equivalent of a hurricane/typhoon.

The upper level trough east of Australia will steer Tropical Cyclone Irene quickly to the east-southeast during the next 24 hours. The center of Irene could pass near the southern islands of Vanuatu in 12 hours. The center of Tropical Cyclone Irene will be near Tanna and Aneityum in 12 hours. Irene could bring strong gusty winds and locally heavy rain to southern Vanuatu. Heavy rain could cause flash floods in some locations.

Tropical Cyclone Cheneso Develops East of Madagascar

Tropical Cyclone Cheneso developed east of northern Madagascar on Wednesday morning. At 4:00 a.m. EST on Wednesday the center of Tropical Cyclone Cheneso was located at latitude 13.8°S and longitude 53.7°E which put it about 245 miles (390 km) east of Sambava, Madagascar. Cheneso was moving toward the west at 13 m.p.h. (20 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 996 mb.

The circulation around a low pressure system over the South Indian Ocean east of northern Madagascar strengthened on Wednesday morning and Meteo France La Reunion designated the system as Tropical Cyclone Cheneso. The inner end of a rainband wrapped around the western and northern sides of the center of Cheneso’s circulation. Other bands of showers and thunderstorms were in the western half of Tropical Cyclone Cheneso. Bands in the eastern half of Cheneso consisted primarily of showers and lower clouds, although there were also some thunderstorms in that side of the circulation. 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 115 miles (185 km) from the center of Tropical Cyclone Cheneso.

Tropical Cyclone Cheneso will move through an environment favorable for intensification during the next 18 hours. Cheneso will move over over water where the Sea Surface Temperatures are near than 29˚C. It will move under the western end of the axis of an upper level ridge over the South Indian Ocean. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. Tropical Cyclone Cheneso will strengthen during the next 18 hours and it could intensify rapidly.

Tropical Cyclone Cheneso will move around the northern side of a high pressure system over the South Indian Ocean. The high pressure system will steer Cheneso toward the west during the next 24 hours. On its anticipated track Tropical Cyclone Cheneso could reach landfall on the northern coast of Madagascar near Sambava in 18h ours. Cheneso will bring strong winds and locally heavy rain to northern Madagascar. Heavy rain could cause flash floods in some locations.

Tropical Cyclone Development Unlikely

The National Hurricane Center indicated on Monday that a strong extratropical cyclone over the Atlantic Ocean south of Nova Scotia is unlikely to make a transition to a tropical cyclone. At 1:00 p.m. EST on Monday the center of the extratropical cyclone was located at latitude 37.8°N and longitude 63.8°W which put it about 460 miles (745 km) south of Halifax, Nova Scotia. The extratropical cyclone was moving toward the north-northeast at 10 m.p.h. (16 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 986 mb.

The National Hurricane Center (NHC) issued a special Tropical Weather Outlook on Monday morning for a strong extratropical cyclone over the Atlantic Ocean south of Nova Scotia. NHC indicated in the Tropical Weather Outlook that it was unlikely the extratropical cyclone would make a transition to a tropical cyclone or a subtropical cyclone. The extratropical cyclone was subsequently designated at Invest 90L.

A circular area of showers and thunderstorms developed at the center of a large, occluded extratropical cyclone south of Nova Scotia on Monday. A clear circular area was visible at the center of the area of showers and thunderstorms on satellite images. The clear area resembled the appearance of an eye in a tropical cyclone. The thunderstorms did not extend high into the troposphere because the center of the extratropical cyclone was over water where the Sea Surface Temperatures are near 20˚C. The circular area of showers and thunderstorms in the middle of the extratropical cyclone was surrounded by a large area of cold, dry air. Bands of low clouds and showers were occurring in the cold, dry air. The extratropical cyclone was producing a large area of winds to tropical storm force.

The extratropical cyclone will move through an area that is only marginally favorable for a transition to a subtropical cyclone or a tropical cyclone. The extratropical cyclone will move over over water where the Sea Surface Temperatures are colder than 20˚C. It will move under the eastern part of an upper level low south of Nova Scotia. The upper level low will produce southerly winds that will blow toward the top of the extatropical cyclone. However, the upper level low is almost stacked vertically with the surface low pressure systems. So, the winds at different levels of the atmosphere are similar and there will be little vertical wind shear. Cold, dry air will continue to surrounded the circular area of thunderstorms at the center of the extratropical cyclone. Cold Sea Surface Temperatures and cold, dry air around the area of thunderstorms will inhibit a transition to a subtropical cyclone. There is a slight chance the extratropical cyclone could make a transition to a subtropical cyclone during the next 24 hours before it moves over even colder water.

The upper level low will steer the extratropical cyclone toward the north during the next 24 hours. On its anticipated track the extratropical cyclone could reach Nova Scotia on Tuesday. It will bring gusty winds and locally heavy rain to Nova Scotia.

Former Tropical Cyclone Ellie Causes Flooding in Western Australia

Former Tropical Cyclone Ellie was causing flooding in parts of Western Australia on Wednesday. At 7:00 a.m. EST on Wednesday the center of former Tropical Cyclone Ellie was located at latitude 17.8°S and longitude 123.3°E which put it about 70 miles (110 km) east of Broome, Australia. Ellie was moving toward the west at 3 m.p.h. (5 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 990 mb.

Former Tropical Cyclone Ellie continued to drop heavy rain over parts of Western Australia on Wednesday and major flooding was occurring along the Fitzroy River. Ellie dropped between 5.1 to 20.4 inches (200 to 800 mm) of rain over the Kimberley region during the past seven days. Major flooding was occurring at Fitzroy Crossing where the water level reached 52 feet (15.81 m). The Fitzroy River at Noonkanbah was 40 feet (12.31 m) and moderate flooding was occurring. The Fitzroy River was at 24 feet (7.26 m) at Willare and minor flooding was occurring.

Former Tropical Cyclone Ellie was also bringing gusty winds to parts of Western Australia. A weather station at Broome Port reported a sustained wind speed of 39 m.p.h. (63 km/h) and a gust of 49 m.p.h. (74 km/h). The weather station at Broome Port reported a wind gust of 59 m.p.h. (95 km/h) a few hours ago. A weather station in Derby reported a sustained wind speed of 28 m.p.h. (46 km/h) and a wind gust of 32 m.p.h. (52 km/h). The weather station in Derby reported a wind gust of 55 m.p.h. (89 km/h) a few hours ago.

The circulation around former Tropical Cyclone Ellie was still very well organized. The strongest winds were occurring in bands of thunderstorms over water and near the coast of Western Australia. Thunderstorms were occurring in bands in the southern and western sides of Ellie’s circulation. Bands in the northern and eastern sides of the circulation consisted primarily of showers and lower clouds. Storms near the center of Ellie generated upper level divergence that pumped mass away from the former tropical cyclone. The removal of mass allowed the surface pressure to remain near 990 mb even though the center of circulation was over land.

Former Tropical Cyclone Ellie is likely to remain nearly stationary near Broome during the next 24 hours. The bands of thunderstorms are likely to continue to drop locally heavy rain over parts of Western Australia. A Major Flood Warning remains in effect for the Fitzroy River. A Flood Warning is in effect for the West Kimberley District. A Flood Watch is in effect for the Sandy Desert.

Former Tropical Cyclone Ellie is likely to maintain its intensity during the next 24 hours. About half of Ellie’s circulation will be over over water where the Sea Surface Temperatures are near 29˚C. It will be under the axis of an upper level ridge over northern Australia. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. Former Tropical Cyclone Ellie is forecast to move toward the east-southeast later this week. Ellie is likely to weaken when the entire circulation moves back over land.

Former Tropical Cyclone Ellie Meanders over Northwestern Australia

Former Tropical Cyclone Ellie was still meandering over northwestern Australia on Monday morning. At 4:00 a.m. EST on Monday the center of former Tropical Cyclone Ellie was located at latitude 17.8°S and longitude 127.1°E which put it about 320 miles (520 km) east of Broome, Australia. Ellie was nearly stationary. The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h). The minimum surface pressure was 993 mb.

The circulation of former Tropical Cyclone Ellie was still meandering over northwestern Australia more than ten days after it made landfall on the coast southwest of Darwin. The circulation around Ellie was still well organized. Thunderstorms were occurring in bands in the western half of Ellie’s circulation. Bands in the eastern half of the circulation consisted primarily of showers and lower clouds. The thunderstorms in the western half of the circulation were dropping heavy rain in some locations. A Major Flood Warning was in effect for the Fitzroy River. A Flood Warning was in effect for the West Kimberley District.

Former Tropical Cyclone Ellie will move around the northwestern part of a high pressure system over Australia. The high pressure system will steer Ellie slowly toward the west during the next 48 hours. On its anticipated track, the center of former Tropical Cyclone Ellie could move back over water near Broome later this week. If the center moves over water, then Ellie will be in an environment favorable for intensification. Ellie will move over over water where the Sea Surface Temperatures are near 29˚C. It will be under the axis of an upper level ridge over northern Australia. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. Ellie could strengthen back to a tropical cyclone if the center moves back over water later this week.

Tropical Cyclone Darian Weakens Southeast of Rodrigues

Tropical Cyclone Darian weakened over the South Pacific Ocean southeast of Rodrigues on Thursday night. At 10:00 p.m. EST on Thursday the center of Tropical Cyclone Darian was located at latitude 26.6°S and longitude 69.9°E which put it about 635 miles (1025 km) southeast of Rodrigues. Darian was moving toward the southwest 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 994 mb.

A combination of cooler Sea Surface Temperatures and moderate vertical wind shear caused Tropical Cyclone Darian to weaken on Thursday night as it moved over the South Indian Ocean on Thursday night. Darian was moving over water where the Sea Surface Temperatures are near 25˚C. An upper level trough east of Madagascar was producing northwesterly winds that were blowing toward the top of Darian’s circulation. Those winds were causing moderate vertical wind shear. The wind shear and cooler water were also affecting the structure of Tropical Cyclone Darian. Thunderstorms were occurring bands in the southeastern part of Darian’s circulation. Bands in the other parts of Tropical Cyclone Darian consisted primarily of showers and lower clouds. There was still a large circulation around Darian. Winds to tropical storm force extended out 160 miles (260 km) from the center of circulation.

Tropical Cyclone Darian will move through an environment unfavorable for a tropical cyclone during the next few days. Darian will move over water where the Sea Surface Temperatures are colder than 25˚C. The upper level trough east of Madagascar will continue to cause moderate vertical wind shear. Cooler water and moderate vertical wind shear will cause Tropical Cyclone Darian to make a transition to an extratropical cyclone during the next few days. Darian could maintain its intensity while it goes the through the transition to an extratropical cyclone.

The upper level trough east of Madagascar will steer Tropical Cyclone Darian toward the south during the next 48 hours. On its anticipated track, Darian will move farther away from Rodrigues, Mauritius and La Reunion.

Tropical Cyclone Darian Weakens over South Indian Ocean

Tropical Cyclone Darian weakened over the South Indian Ocean on Tuesday. At 10:00 p.m. EST on Tuesday the center of Tropical Cyclone Darian was located at latitude 19.9°S and longitude 78.5°E which put it about 965 miles (1560 km) south-southeast of Diego Garcia. Darian was moving toward the southwest at 15 m.p.h. (24 km/h). The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 90 m.p.h. (145 km/h). The minimum surface pressure was 984 mb.

Tropical Cyclone Darian weakened to the equivalent of a tropical storm when it moved over cooler water in the South Indian Ocean on Tuesday night. Thunderstorms did not grow as high into the atmosphere after Darian moved over cooler water. Thunderstorms were still occurring in bands in the southern half of Tropical Cyclone Darian’s circulation on Tuesday night. Bands in the northern half of the circulation consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 200 miles (325 km) from the center of circulation.

Tropical Cyclone Darian will move through an environment unfavorable for a tropical cyclone during the next few days. Darian will move over water where the Sea Surface Temperatures are colder than 25˚C. It will move under the western end of an upper level ridge over the South Indian Ocean. The ridge will produce northerly winds that will blow toward the top of Darian’s circulation. Those winds will cause moderate vertical wind shear. A combination of colder water and moderate vertical wind shear will cause Tropical Cyclone Darian to continue to weaken during the next 36 hours.

Tropical Cyclone Darian will move around the northwestern part of a high pressure system over the South Indian Ocean. The high pressure system will steer Darian toward the southwest during the next 36 hours. On it anticipated track, Tropical Cyclone Darian will pass far to the south of Diego Garcia in 24 hours. Darian could be southeast of Rodrigues in 48 hours.

Tropical Cyclone Darian Strengthens Back to Equivalent of a Major Hurricane

Tropical Cyclone Darian strengthened back to the equivalent of a major hurricane over the South Indian Ocean southeast of Diego Garcia on Monday. At 10:00 a.m. EST on Monday the center of Tropical Cyclone Darian was located at latitude 16.9°S and longitude 84.5°E which put it about 1060 miles (1710 km) southeast of Diego Garcia. Darian was moving toward the southwest at 4 m.p.h. (6 km/h). The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 155 m.p.h. (250 km/h). The minimum surface pressure was 947 mb.

After completing several eyewall replacement cycles during the past 36 hours, Tropical Cyclone Darian strengthened back to the equivalent of a major hurricane over the South Indian Ocean far to the southeast of Diego Garcia. A circular eye with a diameter of 35 miles (55 km) was at the center of Darian’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 Darian. Storms near the core generated upper level divergence that pumped mass away from the tropical cyclone.

The completed eyewall replacements cycles increased the size of the circulation around Tropical Cyclone Darian. Winds to hurricane/typhoon force extended out 50 miles (80 km) from the center of Darian. Winds to tropical storm force extended out 195 miles (305 km) from the center of circulation. The Hurricane Intensity Index (HII) for Tropical Cyclone Darian was 23.6. The Hurricane Size Index (HSI) was 19.4 and the Hurricane Wind Intensity Size Index (HWISI) was 43.0.

Tropical Cyclone Darian will move through an environment favorable for a strong tropical cyclone during the next 24 hours. Darian 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 be little vertical wind shear. If the inner end of a rainband wraps around the core of Tropical Cyclone Darian, then another eyewall replacement cycle could begin. A new eyewall replacement cycle would cause Darian to weaken again. Tropical Cyclone Darian will move over cooler water later this week, which is likely to cause a steadier weakening trend.

Tropical Cyclone Darian will move around the northwestern part of a high pressure system over the South Indian Ocean. The high pressure system will steer Darian toward the southwest during the next few days. On its anticipated track, Tropical Cyclone Darian will pass far to the south of Diego Garcia. Darian could be southeast of Rodrigues in three days.

Tropical Cyclone Darian Spins over South Indian Ocean

Tropical Cyclone Darian was spinning over the South Indian Ocean on Saturday night. At 10:00 p.m. EST on Saturday the center of Tropical Cyclone Darian was located at latitude 14.8°S and longitude 84.8°E which put it about 970 miles (1565 km) east-southeast of Diego Garcia. Darian was moving toward the south-southeast at 13 m.p.h. (20 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 964 mb.

Tropical Cyclone Darian weakened as it spun over the South Indian Ocean on Saturday night. A break developed in the northeastern part of the ring of thunderstorms around the center of Darian’s circulation. The distribution of thunderstorms also became asymmetrical. Many of the thunderstorms were occurring in bands in the western half of Tropical Cyclone Darian. Bands in the eastern half of Darian consisted primarily of showers and lower clouds. Storms near the center of circulation still generated upper level divergence that pumped mass away to the south of the tropical cyclone.

The circulation around Tropical Cyclone Darian was still well organized. Winds to hurricane/typhoon force extended out 45 miles (75 km) from the center of Darian. Winds to tropical storm force extended out 160 miles (260 km) from the center of circulation. The Hurricane Intensity Index (HII) for Tropical Cyclone Darian was 17.8. The Hurricane Size Index (HSI) was 18.2 and the Hurricane Wind Intensity Size Index (HWISI) was 36.0.

Tropical Cyclone Darian will move through an environment unfavorable for intensification during the next 24 hours. Darian will move over water where the Sea Surface Temperatures are near 27˚C. It will move under the western part of an upper level ridge centered west of Australia. The ridge will produce northeasterly winds that will blow toward the top of Darian’s circulation. Those winds will cause vertical wind shear. The wind shear may already be contributing to the asymmetrical distribution of thunderstorms. The wind shear is likely to be strong enough to cause Tropical Cyclone Darian to weaken during the next 24hours.

The upper level ridge west of Australia will steer Tropical Cyclone Darian toward the south during the next 24 hours. On its anticipated track, Tropical Cyclone Darian will move farther away from Diego Garcia.

Tropical Cyclone Darian Intensifies to Nearly Equivalent of Cat. 5 Hurricane

Tropical Cyclone Darian intensified to nearly the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale on Friday. At 10:00 a.m. EST on Friday the center of Tropical Cyclone Darian was located at latitude 12.4°S and longitude 83.6°E which put it about 850 miles (1375 km) east-southeast of Diego Garcia. Darian was moving toward the west at 6 m.p.h. (10 km/h). The maximum sustained wind speed was 155 m.p.h. (250 km/h) and there were wind gusts to 190 m.p.h. (305 km/h). The minimum surface pressure was 920 mb.

Tropical Cyclone Darian appeared to go through an eyewall replacement cycle on Thursday. The inner end of a rainband wrapped around the original eye and eyewall. Two concentric eyewalls were evident on some microwave satellite images. Darian weakened during the eyewall replacement cycle. The original inner eyewall eventually dissipated and Tropical Cyclone Darian intensified rapidly on Friday. The new eyewall contracted around the center of Darian and a small eye was at the center of 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 Darian. Storm near the core generated upper level divergence that pumped mass away from the tropical cyclone.

The size of Tropical Cyclone Darian increased after the eyewall replacement cycle. Winds to hurricane/typhoon force extended out 60 miles (95 km) from the center of Darian. Winds to tropical storm force extended out 185 miles (295 km) from the center of circulation. The Hurricane Intensity Index (HII) for Tropical Cyclone Darian was 33.3. The Hurricane Size Index (HSI) was 20.7 and the Hurricane Wind Intensity Size Index (HWISI) was 54.0.

Tropical Cyclone Darian will move through an environment favorable for a strong tropical cyclone during the next 24 hours. Darian 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 be little vertical wind shear. Tropical Cyclone Darian could maintain its intensity during the next 24 hours. If the inner end of a rainband wraps around the existing eye and eyewall, then another eyewall replace cycle could begin. An eyewall replacement cycle would cause Darian to weaken again.

An upper level trough west of Australia will strengthen during the next 36 hours. Northwesterly winds blowing around the western side of the trough will steer Tropical Cyclone Darian toward the south-southeast during that time period. On its anticipated track Darian will move farther away from Diego Garcia.

Elsewhere, Tropical Cyclone Ellie dropped locally heavy rain over parts of the Northern Territory in Australia. At 10:00 a.m. EST on Friday the center of Tropical Cyclone Ellie was located at latitude 15.8°S and longitude 131.0°E which put it about 150 miles (240 km) north-northwest of Daly Waters, Australia. Ellie was moving toward the south-southeast at 11 m.p.h. (17 km/h). The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (95 km/h). The minimum surface pressure was 999 mb.