Subtropical Cyclone Develops Over South Atlantic Ocean

A subtropical cyclone developed over the South Atlantic Ocean southeast of Brazil on Monday. At 1:00 p.m. EST on Monday the center of a subtropical cyclone was located at latitude 30.0°S and longitude 42.0°W which put it about 570 miles (920 km) east-southeast of Porto Alegre, Brazil. It was moving toward the southwest at 4 m.p.h. (6 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.

A low pressure system over the South Atlantic Ocean southeast of Brazil exhibited more organization on Monday and the National Institute of Meteorology in Brazil classified the system as a subtropical depression. The subtropical cyclone had a well defined center of circulation in the lower levels of the atmosphere. Bands of showers and lower clouds were revolving around the center of circulation. A stronger rainband coiled around the northern and western side of the subtropical cyclone.

The subtropical cyclone will move through an environment unfavorable for intensification during the next 24 hours. It will move over water where the Sea Surface Temperatures are near 24°C. The subtropical cyclone will move under the western part of an upper level ridge over the South Atlantic Ocean. The upper level ridge will produce strong northerly winds that will blow across the top of the subtropical cyclone. Those winds will cause strong vertical wind shear. The strong wind shear and marginal Sea Surface Temperatures are likely to cause the subtropical cyclone to weaken slowly during the next 24 hours.

The subtropical cyclone will move around the western side of a high pressure system over the South Atlantic Ocean. The high pressure system will steer the subtropical cyclone slowly toward the south during the next 24 hours. On its anticipated track, the subtropical cyclone will remain east of South America.

Tropical Cyclone Djoungou Strengthens to Equivalent of Cat. 4 Hurricane

Tropical Cyclone Djoungou strengthened to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale over the South Indian Ocean on Sunday. At 4:00 p.m. EST on Sunday the center of Tropical Cyclone Djoungou was located at latitude 22.5°S and longitude 82.3°E which put it about 1150 miles (1855 km) south-southeast of Diego Garcia. Djoungou was moving toward the southeast at 33 m.p.h. (54 km/h). The maximum sustained wind speed was 140 m.p.h. (220 km/h) and there were wind gusts to 165 m.p.h. (265 km/h). The minimum surface pressure was 942 mb.

A small circular was visible at the center of Tropical Cyclone Djoungou earlier on Sunday, but the eye was no longer evident on Sunday afternoon. 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 were revolving around the core of Tropical Cyclone Djoungou. Storms near the core generated strong upper level divergence that pumped lmass away from the tropical cyclone.

The size of the circulation around Tropical Cyclone Djoungou increased on Sunday. Winds to hurricane/typhoon force extended out 70 miles (110 km) from the center of Djoungou’s circulation. Winds to tropical storm force extended out 200 miles (320 km) from the center of circulation. The Hurricane Intensity Index (HII) for Tropical Cyclone Djoungou was 28.2. The Hurricane Size Index (HSI) was 25.7 and the Hurricane Wind Intensity Size Index (HWISI) was 53.9.

Tropical Cyclone Djoungou will move through an environment unfavorable for a strong tropical cyclone during the next 36 hours. Djoungou will move over water where the Sea Surface Temperatures are near 26°C. It will move under the eastern part of an upper level trough over the South Indian Ocean. The upper level trough will produce strong northwesterly winds that will blow toward the top of Djoungou’s circulation. Those winds will cause strong vertical wind shear. Strong vertical wind shear and cooler water will cause Tropical Cyclone Djoungou to weaken rapidly during the next 36 hours.

Tropical Cyclone Djoungou will move around the southern side of a high pressure system over the South Indian Ocean. The high pressure system will steer Djoungou toward the east-southeast during the next 36 hours. On its anticipated track, Tropical Cyclone Djoungou will move far to the south of the Cocos Islands in 36 hours.

Elsewhere over the South Indian Ocean, a tropical depression formed northwest of Mauritius. At 1:00 p.m. EST on Sunday the center of the tropical depression was located at latitude 15.5°S and longitude 5363°E which put it about 405 miles (650 km) northwest of Port Louis, Mauritius. The tropical depression was moving toward the east-northeast 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. (65 km/h). The minimum surface pressure was 1004 mb.

Tropical Cyclone Djoungou Rapidly Intensifies to Equivalent of a Major Hurricane

Tropical Cyclone Djoungou rapidly intensified to the equivalent of a major hurricane over the South Indian Ocean south of Diego Garcia on Saturday. At 4:00 p.m. EST on Saturday the center of Tropical Cyclone Djoungou was located at latitude 17.1°S and longitude 73.3°E which put it about 660 miles (1065 km) south of Diego Garcia. Djoungou was moving toward the east-southeast at 22 m.p.h. (35 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 960 mb.

A small circular eye formed at the center of Tropical Cyclone Djoungou as it rapidly intensified on Saturday. 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 were revolving around the core of Tropical Cyclone Djoungou. Storms near the core generated strong upper level divergence that pumped large quantities of mass away from the tropical cyclone. The removal of large amounts of mass caused the surface pressure to decrease rapidly.

The circulation around Tropical Cyclone Djoungou also became more symmetrical when Djoungou rapidly intensified. Winds to hurricane/typhoon force extended out 50 miles (80 km) from the center of Djoungou’s circulation. Winds to tropical storm force extended out 185 miles (295 km) from the center of circulation. The Hurricane Intensity Index (HII) for Tropical Cyclone Djoungou was 20.6. The Hurricane Size Index (HSI) was 20.2 and the Hurricane Wind Intensity Size Index (HWISI) was 40.8.

Tropical Cyclone Djoungou will move through an environment favorable for intensification during the next 24 hours. Djoungou 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 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 Djoungou is likely to intensify during the next 24 hours. However, Djoungou could start to weaken if the inner end of a rainband wraps around the existing eye and eyewall and concentric eyewalls form.

Tropical Cyclone Djoungou will move around the southern side of a high pressure system over the South Indian Ocean. The high pressure system will steer Djoungou toward the east-southeast during the next 24 hours. On its anticipated track, Tropical Cyclone Djoungou will move farther southeast of Diego Garcia.

Tropical Cyclone Djoungou Intensifies to Equivalent of Hurricane/Typhoon

Tropical Cyclone Djoungou intensified to the equivalent of a hurricane/typhoon over the South Indian Ocean on Friday. At 4:00 p.m. EST on Friday the center of Tropical Cyclone Djoungou was located at latitude 16.2°S and longitude 67.1°E which put it about 745 miles (1200 km) south-southwest of Diego Garcia. Djoungou was moving toward the east at 6 m.p.h. (10 km/h). The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h). The minimum surface pressure was 988 mb.

Tropical Cyclone Djoungou intensified rapidly over the South Indian Ocean on Friday. The inner end of a rainband wrapped around the center of Djoungou’s circulation. A small eye was visible intermittently at the center of Tropical Cyclone Djoungou. The developing eye was surrounded by a 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 Djoungou. Storms near the core generated upper level divergence that pumped mass away from the tropical cyclone. The removal of mass caused the surface pressure to decrease.

Winds to hurricane/typhoon force extended out 45 miles (75 km) from the center of Tropical Cyclone Djoungou. Winds to tropical storm force extended out 175 miles (280 km) in the northeastern quadrant of Djoungou’s circulation. Winds to tropical storm force extended out 80 miles (130 km) in the other parts of Tropical Cyclone Djoungou.

Tropical Cyclone Djoungou will move through an environment very favorable for intensification during the next 36 hours. Djoungou 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 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 Djoungou will intensify during the next 36 hours. Djoungou could intensify more rapidly once the eye and eyewall are fully formed. Tropical Cyclone Djoungou could strengthen to the equivalent of a major hurricane during the weekend.

Tropical Cyclone Djoungou will move around the southern side of a high pressure system over the South Indian Ocean. The high pressure system will steer Djoungou toward the east-southeast during the next 36 hours. On its anticipated track, Tropical Cyclone Djoungou will pass south of Diego Garcia in 24 hours.

Tropical Cyclone Lincoln Develops Over Gulf of Carpentaria

Tropical Cyclone Lincoln developed over the southwest Gulf of Carpentaria on Thursday night. At 10:00 p.m. EST on Thursday the center of Tropical Cyclone Lincoln was located at latitude 15.7°S and longitude 137.3°E which put it about 135 miles (220 km) northwest of Mornington Island. Lincoln was nearly stationary. 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.

A Warning was in effect from Bing Bong, Northern Territory to Mornington Island, Queensland including Port McArthur and Borroloola.

A tropical low pressure system over the southwest Gulf of Carpentaria strengthened on Thursday night and the Australian Bureau of Meteorology designated the system as Tropical Cyclone Lincoln. A band of showers and thunderstorms wrapped around the western side of the center of Lincoln’s circulation. Storms near the center of circulation generated upper level divergence that pumped mass away from the tropical cyclone. Other bands of thunderstorms were in the eastern periphery of Tropical Cyclone Lincoln. Winds to tropical storm force extended out 60 miles from the center of Lincoln’s circulation.

Tropical Cyclone Lincoln will move through an environment favorable for intensification during the next few hours. Lincoln will move over water where the Sea Surface Temperatures are near 31°C. It will move under 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. Tropical Cyclone Lincoln could intensify during the next few hours.

Tropical Cyclone Lincoln will move around the northwestern part of a high pressure system over eastern Australia. The high pressure system will steer Lincoln toward the southwest during the next 24 hours. On its anticipated track, the center of Tropical Cyclone Lincoln will make landfall between Port McArthur and the border between the Northern Territory and Queensland in a few hours. Lincoln will bring gusty winds and locally heavy rain to the eastern part of the Northern Territory and northwestern Queensland. Heavy rain could cause flash floods in some locations.

Tropical Cyclone Djoungou Develops North of Rodrigues

Tropical Cyclone Djoungou developed over the South Indian Ocean north of Rodrigues on Thursday. At 4:00 p.m. EST on Thursday the center of Tropical Cyclone Djoungou was located at latitude 15.3°S and longitude 65.1°E which put it about 315 miles (505 km) north-northeast of Port Mathurin, Rodrigues. Djoungou was moving toward the east at 7 m.p.h. (11 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 1001 mb.

A low pressure system over the South Indian Ocean north of Rodrigues strengthened on Thursday and Meteo France La Reunion designated the system as Tropical Cyclone Djoungou. The circulation around Djoungou was organizing quickly. The inner end of a rainband wrapped around the eastern and southern sides of the center of Tropical Cyclone Djoungou. Storms near the center of Djoungou’s circulation generated upper level divergence that pumped mass away from the tropical cyclone. Thunderstorms developed in bands in the northern and eastern parts of Tropical Cyclone Djoungou. Bands in the western part of Djoungou’s circulation consisted primarily of showers and lower clouds.

The distribution of wind speeds around Tropical Cyclone Djoungou was asymmetrical. Winds to tropical storm force extended out 175 miles (280 km) in the northeastern quadrant of Djoungou’s circulation. Winds to tropical storm force extended out 45 miles (75 km) in the southeastern quadrant of Tropical Cyclone Djoungou. The winds in the western half of Djoungou were blowing at less than tropical storm force.

Tropical Cyclone Djoungou will move through an environment very favorable for intensification during the next 24 hours. Djoungou 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 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 Djoungou will intensify during the next 24 hours. Djoungou could intensify rapidly at times. Tropical Cyclone Djoungou could strengthen to the equivalent of a major hurricane during the weekend.

Tropical Cyclone Djoungou will move around the southern side of a high pressure system over the South Indian Ocean. The high pressure system will steer Djoungou toward the east during the next 24 hours. On its anticipated track, Tropical Cyclone Djoungou will move farther away from Rodrigues. Djoungou could pass south of Diego Garcia in a few days.

Tropical Cyclone Nat Moves Southwest of Tahiti

Tropical Cyclone Nat moved southwest of Tahiti on Wednesday. At 4:00 p.m. EST on Wednesday the center of Tropical Cyclone Nat was located at latitude 19.5°S and longitude 151.2°W which put it about 185 miles (300 km) southwest of Papeete, Tahiti. Nat was moving toward the southeast at 6 m.p.h. (10 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 998 mb.

Tropical Cyclone Nat brought rain showers and gusty winds to Tahiti on Wednesday. Nat started to weaken as it moved southwest of Tahiti. An upper level trough northeast of New Zealand produced strong westerly winds that blew across the top of Nat’s circulation. Those winds cause strong vertical wind shear. The strong upper level winds blew away the tops of many of the thunderstorms in Tropical Cyclone Nat. A few thunderstorms persisted in a band in the far eastern edge of Nat’s circulation. Other bands revolving around the center of Tropical Cyclone Nat consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 75 miles (120 km) from the center of Nat’s circulation.

Tropical Cyclone Nat will move through an environment unfavorable for intensification during the next 24 hours. Nat will move over water where the Sea Surface Temperatures are near 29°C. However, the upper level trough northeast of New Zealand will continue to cause strong vertical wind shear. The strong vertical wind shear will cause Tropical Cyclone Nat to continue to weaken during the next 24 hours.

The upper level trough northeast of New Zealand will steer Tropical Cyclone Nat toward the east during the next 24 hours. On its anticipated track, the center of Tropical Cyclone Nat will pass south of Tahiti. Bands in the northern side of Nat will continue to bring gusty winds and rain showers to Tahiti during the next 24 hours.

Elsewhere over the South Pacific Ocean, Tropical Cyclone Osai strengthened west of Palmerston Island. At 4:00 p.m. EST on Wednesday the center of Tropical Cyclone Osai was located at latitude 18.1°S and longitude 164.4°W which put it about 85 miles (135 km) west of Palmerston Island. Osai was moving toward the southeast at 18 m.p.h. (29 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 993 mb.

Tropical Cyclone Nat Moves Toward Tahiti

Tropical Cyclone Nat moved toward Tahiti on Tuesday. At 4:00 p.m. EST on Tuesday the center of Tropical Cyclone Nat was located at latitude 17.6°S and longitude 155.4°W which put it about 415 miles (670 km) west of Pappete, Tahiti. Nat was moving toward the east-southeast at 20 m.p.h. (32 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 993 mb.

Tropical Cyclone Nat strengthened a little as it moved over the South Pacific Ocean toward Tahiti on Tuesday. Thunderstorms continued to form near the center of Nat’s circulation. Storms near the center of circulation generated upper level divergence that pumped mass away to the east of the tropical cyclone. Thunderstorms were also occurring in bands in the northern and eastern parts of Tropical Cyclone Nat. Bands in the western and southern part of Nat’s circulation consisted primarily of showers and lower clouds. Winds to tropical storm force extend out 120 miles (195 km) in the northwest, northeast and southeast quadrants of Tropical Cyclone Nat. Winds to tropical storm force only extended out 40 miles (65 km) in the southwest quadrant of Nat.

Tropical Cyclone Nat will move through an environment unfavorable for intensification during the next 24 hours. Nat will move over water where the Sea Surface Temperatures are near 29°C. It will move under the eastern side of an upper level trough over the South Pacific Ocean northeast of New Zealand. The upper level trough will produce strong northwesterly winds that will blow toward the top of Nat’s circulation. Those winds will cause strong vertical wind shear. The strong vertical wind shear is likely to cause Tropical Cyclone Nat to start to weaken during the next 24 hours.

The upper level trough northeast of New Zealand will steer Tropical Cyclone Nat toward the east-southeast during the next 24 hours. On its anticipated track, the center of Tropical Cyclone Nat will pass south of Bora Bora during the next 24 hours. Nat could be near Tahiti within 36 hours. Bands in the northern side of Nat could bring gusty winds and locally heavy rain to the Society Islands. Heavy rain could cause flash floods in some locations.

Elsewhere over the South Pacific Ocean, Tropical Cyclone 11P formed north of American Samoa. At 4:00 p.m. EST on Tuesday the center of Tropical Cyclone 11P was located at latitude 13.3°S and longitude 168.9°W which put it about 110 miles (195 km) north of Pago Pago, American Samoa. The tropical cyclone was moving toward the southeast at 21 m.p.h. (33 km/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. Heavy rain could cause flash floods in parts of American Samoa.

Tropical Cyclone Nat Forms West of Tahiti

Tropical Cyclone Nat formed over the South Pacific Ocean west of Tahiti on Monday. At 1:00 p.m. EST on Monday the center of Tropical Cyclone Nat was located at latitude 15.3°S and longitude 163.6°W which put it about 965 miles (1560 km) west of Pappete, Tahiti. Nat was moving toward the east-southeast at 15 m.p.h. (24 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 996 mb.

A low pressure system over the South Pacific Ocean between Samoa and Tahiti strengthened on Monday and the Fiji Meteorological Service designated the system as Tropical Cyclone Nat. More thunderstorms formed near the center of Tropical Cyclone Nat. Storms near the center of Nat’s circulation generated upper level divergence that pumped mass away to the east of the tropical cyclone. Thunderstorms were also occurring in bands in the northern and eastern parts of Tropical Cyclone Nat. Bands in the western and southern part of Nat’s circulation consisted primarily of showers and lower clouds. Winds to tropical storm force extend out 160 miles (260 km) in the northwest, northeast and southeast quadrants of Tropical Cyclone Nat. Winds to tropical storm force only extended out 25 miles (40 km) in the southwest quadrant of Nat.

Tropical Cyclone Nat will move through an environment somewhat favorable for intensification during the next 24 hours. Nat will move over water where the Sea Surface Temperatures are near 30°C. It will move under the eastern side of an upper level trough over the South Pacific Ocean northeast of New Zealand. The upper level trough will produce northwesterly winds that will blow toward the top of Nat’s circulation. Those winds will cause moderate vertical wind shear. The wind shear will inhibit intensification, but the shear may not be strong enough to prevent intensification. Tropical Cyclone Nat could intensify gradually during the next 24 hours.

The upper level trough northeast of New Zealand will steer Tropical Cyclone Nat toward the east-southeast during the next 24 hours. On its anticipated track, Nat will move closer to Tahiti. The center of Tropical Cyclone Nat is forecast to pass north of Palmerston, Aitutaki and Mauke. The winds blowing around the southern side of Nat’s could bring gusty winds and rough seas to those places during the next 24 hours.

Anggrek Transitions to an Extratropical Cyclone

Former Tropical Cyclone Anggrek made a transition to an extratropical cyclone over the South Indian Ocean during Tuesday night. At 4:00 a.m. EST on Wednesday the center of former Tropical Cyclone Anggrek was located at latitude 33.3°S and longitude 84.8°E which put it about 1925 miles (3105 km) south-southeast of Diego Garcia. Anggrek was moving toward the east-southeast at 40 m.p.h. (65 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 983 mb.

Former Tropical Cyclone Anggrek made a transition to a powerful extratropical cyclone over the South Indian Ocean. Anggrek moved over water where the Sea Surface Temperatures are near 22°C. It moved under the eastern side of an upper level trough that is east of Madagascar. The upper level trough produced northwesterly winds that caused strong vertical wind shear. The combination of colder water and strong wind shear caused formal Tropical Cyclone Anggrek to make a transition to an extratropical cyclone.

The transition to an extratropical cyclone also caused changes to the structure of former Tropical Cyclone Anggrek. The strong northwesterly winds in the upper levels of the atmosphere blew the tops off of many of the thunderstorms in Anggrek’s circulation. Thunderstorms were still occurring in bands in the southern part of former Tropical Cyclone Anggrek. Bands in the northern part of the circulation consisted primarily of showers and lower clouds. Winds to hurricane/typhoon force extended out 70 miles (110 km) in the eastern side of former Tropical Cyclone Anggrek. Winds to tropical storm force extended out 140 miles (220 km) from the center of Anggrek’s circulation.

The upper level trough east of Madagascar will steer former Tropical Cyclone Anggrek quickly toward the east-southeast. On its anticipated track, Former Tropical Cyclone Anggrek could approach southwestern Australia later this week.

Elsewhere over the South Indian Ocean, a tropical depression formed east of Rodrigues. At 10:00 a.m. EST on Wednesday the center of the tropical depression was located at latitude 19.9°S and longitude 66.2°E which put it about 175 miles (280 km) east of Port Mathurin, Rodrigues. The tropical depression was moving toward the south-southeast 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 996 mb.