Category Archives: Indian Ocean

Tropical Cyclone Chapala Makes Landfall in Yemen

Tropical Cyclone Chapala made landfall in Yemen just west of Al Mukalla as the equivalent of a hurricane.  At 10:00 p.m. EDT on Monday the center of Tropical Cyclone Chapala was located at latitude 13.9°N and longitude 48.7°E which put it 30 miles (50 km) south of Al Mukalla, Yemen.  Chapala was moving toward the west-northwest at 10 m.p.h. (16 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/).  The minimum surface pressure was 979 mb.

Tropical Cyclone Chapala reached the western end of the ridge that was steering it toward the west and it turned north toward the coast of Yemen on Monday.  When Chapala reached the western end of the ridge, southerly winds in the upper levels generated vertical wind shear and the circulation of the tropical cyclone tilted toward the north.  In addition, as the core of the circulation neared the coast, it drew in drier air from the Arabian peninsula.  The combination of more wind shear and drier air started to weaken Chapala, but the tropical cyclone was still the equivalent of a hurricane when it made landfall.

The core of Tropical Cyclone Chapala will bring strong winds and heavy rain to the coast.  Although Chapala will weaken fairly quickly as it moves into the dry interior of the Arabian peninsula, the circulation will be capable of producing locally heavy rainfall and flash floods as the tropical cyclone spins down.

Tropical Cyclone Chapala Poised to Enter Gulf of Aden

Tropical Cyclone Chapala continued to move steadily westward on Sunday and it was poised to enter the Gulf of Aden.  At 11:00 p.m. EDT on Sunday the center of Tropical Cyclone Chapala was located at latitude 13.2°N and longitude 52.2°E which put it about 230 miles (370 km) east-southeast of Al Mukalla, Yemen.  Chapala was moving toward the west at 12 m.p.h. (19 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 959 mb.

Chapala is still a very well organized tropical cyclone and it is the equivalent of a major hurricane.  Chapala has a 25 mile (40 km) wide eye, which is surrounded by numerous thunderstorms.  Those storms are generating upper level divergence which is pumping out enough mass to balance the air flowing into the center near the surface.  The balance of inflow and outflow allowed Chapala to maintain its intensity on Sunday.

Tropical Cyclone Chapala is over water where the Sea Surface Temperature is around 28.5°C and the upper level winds are light.  There is little vertical wind shear and most environmental factors support the ability of Tropical Cyclone Chapala to maintain its intensity.  However, once Chapala enters the Gulf of Aden it will have very dry air to its north over the Arabian peninsula and dry air to its south over east Africa.  Chapala will remain a strong tropical cyclone as long as the dry air does not reach its core.  However, as Tropical Cyclone Chapala moves closer to the coast of Yemen, the drier air will probably cause it to start to weaken.

A ridge north of Chapala is steering the tropical cyclone toward the west.  Chapala will reach the western end of the ridge on Monday and the tropical cyclone will turn toward the northwest.  On its anticipated track Chapala will make landfall on the coast of Yemen near Al Mukalla in 24 to 30 hours.  It will bring strong winds and heavy rain to the coast.  Chapala is likely to dissipate quickly as it moves inland over the Arabian peninsula, but it could bring heavy rain and flash floods before it does so.

Strong Tropical Cyclone Chapala on Track for Landfall in Yemen

Strong Tropical Cyclone Chapala moved steadily westward on Saturday and it remains on track for a landfall in Yemen.  At 11:00 p.m. EDT on Saturday the center of Tropical Cyclone Chapala was located at latitude 13.6°N and longitude 56.0°E which put it about 265 miles (425 km) south-southeast of Salalah, Oman and about 465 miles (765 km) east of Al Mukalla, Yemen.  Chapala was moving toward the west at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 135 m.p.h. (215 km) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 952 mb.

Chapala continues to be a strong well organized tropical cyclone and it is the equivalent of a major hurricane.  It has a symmetrical circulation with a well formed eye inside a core of thunderstorms.  Multiple rainbands are rotation around the center of circulation.  Upper level divergence is pumping out mass in all directions.

Tropical Cyclone Chapala remains in a favorable environment.  It is over warm Sea Surface Temperatures and the upper level winds are light.  There is not much vertical wind shear and Chapala could maintain its intensity until it approaches the coast of Yemen.  When Chapala gets nearer the coast, it will start to pull in drier air from the Arabian peninsula.  As Chapala ingests the drier air, it will start to weaken.

A ridge north of Chapala is steering the tropical cyclone westward.  As Chapala nears the western end of the ridge, it will start to turn more toward the west-northwest.  On its anticipated track Tropical Cyclone Chapala will approach the central coast of Yemen in 36 to 48 hours.  The core of Chapala will pass north of the island of Socotra on Sunday.

Tropical Cyclone Chapala Becomes Equivalent of Cat. 4 Hurricane

Tropical Cyclone Chapala intensified rapidly on Friday and it became the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.  At 5:00 p.m. EDT on Friday the center of Tropical Cyclone Chapala was located at latitude 13.9°N and longitude 59.9°E which put it about 405 miles (655 km) east-southeast of Salalah, Oman.  Chapala was moving toward the west-southwest at 5 m.p.h. (8km/h).  The maximum sustained wind speed was 150 m.p.h. (240 km/h) and there were wind gusts to 185 m.p.h. (295 km/h).  The minimum surface pressure was 932 mb.

Tropical Cyclone Chapala is a very well organized tropical cyclone.  It has a well defined eye and a strong core of thunderstorms around the eye.  Those storms generated upper level divergence which pumped out mass and allowed the surface pressure to fall rapidly.

Chapala is an environment favorable for tropical cyclones.  It is over warm Sea Surface Temperatures and the upper level winds are light.  So, there is little vertical wind shear.  However, a secondary eyewall may be developing and eyewall replacement cycles could cause fluctuations in intensity for the next day or two.  When Chapala approaches the Arabian peninsula, it will start to pull in very dry air, and that will weaken the tropical cyclone even before it makes landfall.

A subtropical ridge is steering Chapala toward the west and that general steering motion is expected to continue for another 36 to 48 hours.  As Chapala reaches the western end of the ridge, it could turn more toward the northwest.  Tropical Cyclone Chapala could be approaching the coast of Yemen in 48 to 60 hours.

Tropical Cyclone Chapala Intensifies Rapidly

Tropical Cyclone Chapala intensified rapidly on Thursday and it is almost the equivalent of a major hurricane.  At 11:00 p.m. EDT on Thursday the center of Tropical Cyclone Chapala was located at latitude 14.2°N and longitude 61.5°E which put it about 535 miles (865 km) east-southeast of Salalah, Oman.  Chapala was moving toward the west at 6 m.p.h. (10 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 956 mb.

Chapala has a very well organized, symmetrical circulation.  There is a well formed eye which is surrounded by a ring of strong thunderstorms.  Several spiral bands are rotating around the core of the cyclone.  The thunderstorms surrounding the eye are generating upper level divergence which is pumping out mass in all directions.

Tropical Cyclone Chapala is an environment that favors further intensification.  It is over water where the Sea Surface Temperature is around 28°C.  The upper level winds are light and there is not much vertical wind shear.  Chapala could intensify to the equivalent of a Category 4 hurricane on Friday.  After that time eyewall replacement cycles could cause fluctuations in intensity.

A ridge in north of Chapala is steering the tropical cyclone toward the west.  That same general steering motion is expected to continue for another two or three days.  On its anticipated track Tropical Cyclone Chapala could be approaching the area near the border between Oman and Yemen in 48 to 60 hours.  It could be an intense tropical cyclone at that time.

Tropical Cyclone 04A Organizes in the Arabian Sea

A center of circulation organized quickly within a broader area of thunderstorms over the Arabian Sea on Wednesday and the system was designated Tropical Cyclone 04A.  At 11:00 p.m. EDT on Wednesday the center of Tropical Cyclone 04A was located at latitude 13.7°N and longitude 64.0°E which put it about 705 miles east-southeast of Salalah, Oman.  The tropical cyclone was moving toward the west-northwest at 6 m.p.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 993 mb.

The organization of Tropical Cyclone 04A improved significantly on Wednesday.  A primary rainband wrapped almost entirely around the center of circulation and there were indications on various satellite images that an eye could be forming.  Additional rainbands were beginning to form in the circulation outside the core.  Thunderstorms near the center of circulation were generating upper level divergence, especially on the northeast side of the tropical cyclone.

The environment is favorable for further intensification.  Tropical Cyclone 04A is over water where the Sea Surface Temperature is near 28°C.  Although there are strong upper level westerly winds north of the cyclone, the upper level winds over it are relatively light.  As a result there is not a lot of vertical wind shear over Tropical Cyclone 04A.  The cyclone is likely to intensify during the next several days and it could intensify rapidly.  It could attain hurricane intensity in a day or two and it could eventually become the equivalent of a major hurricane.

A ridge north of Tropical Cyclone 04A is steering it slowly toward the west-northwest.  The ridge is expected to continue steering the cyclone toward the west during the next few days.  On its anticipated track Tropical Cyclone 04A could approach the coast of Oman and Yemen in four or five days.

Tropical Cyclone 02B Forms Near Bangladesh

An area of low pressure over the extreme northern portion of the Bay of Bengal developed enough characteristics of a tropical cyclone to be designated Tropical Cyclone 02B.  At 5:00 a.m. EDT on Wednesday the center of Tropical Cyclone 02B was located at latitude 21.3°N and longitude 91.4°E which put it about 80 miles south-southwest of Chittagong, Bangladesh.  It was moving toward the north-northeast at 4 m.p.h.  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1001 mb.

The circulation around Tropical Cyclone 02B slowly organized during the past several days and it now has the structure of a tropical cyclone.  There are several spiral bands of thunderstorms, although most of the thunderstorms are south of the center due to the proximity to land.  The tropical cyclone is over very warm water where the Sea Surface Temperature is near 31°C, and it has enough energy to intensify.  However, a large upper level ridge over Asia is generating moderate northeasterly winds over the circulation which is producing moderate vertical wind shear.  Proximity to land will also be an inhibiting factor.  Some modest intensification is possible before the center moves over land.

Tropical cyclone 02B is moving around the western end of a subtropical ridge which is steering it northward toward the coast of Bangladesh.  That general steering pattern is expected to continue for another 24 hours.  Then the easterly winds associated with the upper level ridge over Asia are expected to turn Tropical Cyclone 02B toward the west.  On its anticipated track Tropical Cyclone 02B could make landfall over Bangladesh in approximately 24 hours.  Given the bathymetry of the northern Bay of Bengal and the shape of the coast of Bangladesh some storm surge is possible.  Locally heavy rainfall could contribute to flooding as the tropical cyclone moves inland.

Tropical Cyclone Ashobaa Moving Slowly Toward Oman

Tropical Cyclone Ashobaa moved slowly westward toward Oman on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Tropical Cyclone Ashobaa was located at latitude 20.6°N and longitude 61.1°E which put it about 160 miles (260 km) east of Masirah Island, Oman.  Ashobaa was moving toward the west at 4 m.p.h. (6 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 992 mb.

Most of the strong thunderstorms are occurring south and west of the center Ashobaa.  An upper level ridge located over southern Asia is generating easterly winds over the top of the tropical cyclone.  Those easterly winds are producing moderate amounts of vertical wind shear and account for the asymmetric distribution of thunderstorms.  Ashobaa is moving over warm Sea Surface Temperatures and there is enough energy in the upper ocean to support intensification.  However, the vertical shear is strong enough to inhibit intensification.  Once Ashobaa moves closer to the coast of Oman, the circulation will begin to pull in drier air from land.  The tropical cyclone could start to weaken before the center moves on land.

The ridge over southern Asia strengthened on Wednesday and it pushed Ashobaa a little south of due west.  The ridge is expected to remain in place and to continue steering the tropical cyclone westward for the next several days.  On its anticipated track, Ashobaa would make landfall in Oman in about 24 to 36 hours.

Tropical Cyclone Ashobaa Moves Toward Oman

Tropical Cyclone Ashobaa turned toward the west on Tuesday and it now appears on track to make a landfall in Oman.  At 11:00 p.m. EDT on Tuesday the center of Tropical Cyclone Ashobaa was located at latitude 21.2°N and longitude 61.6°E which put it about 200 miles (325 km) east-northeast of Masirah Island, Oman.  Ashobaa was moving toward the west-northwest at 11 m.p.h. (18 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 985 mb.

The circulation around Tropical Cyclone Ashobaa is showing signs of greater organization.  A band of thunderstorms has wrapped around the southern portion of the center of circulation and it could represent the formation of a partial eyewall.  Ashobaa is moving over water where the Sea Surface Temperature is warm, but an upper level ridge north of the tropical cyclone is generating easterly winds.  Those winds are producing some vertical wind shear which is inhibiting intensification.  The shear decreased somewhat on Tuesday and there was a modest increase in the wind speed.  The strong thunderstorms near the center of Ashobaa are generating some upper level divergence, mainly on the western side of the circulation and the tropical cyclone could intensify further during the next 24 hours.  As the circulation nears the coast of Oman, the circulation will start to pull in drier air from land and Ashobaa will start to weaken.

An upper level ridge north Ashobaa has strengthened and it appears the ridge will steer the tropical cyclone westward to the coast of Oman.  On its anticipated track the center of Tropical Cyclone Ashobaa will approach the coast of Oman near As Suwayh in about 24 hours.

Tropical Cyclone Ashobaa Moving South of Pakistan

Tropical Cyclone Ashobaa moved northwestward across the Arabian Sea south of Pakistan on Monday.  At 11:00 p.m. EDT on Monday the center of Tropical Cyclone Ashobaa was located at latitude 20.4° and longitude 64.8°W which put it about 340 miles (550 km) south-southwest of Karachi, Pakistan.  Ashobaa was moving toward the northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 990 mb.

More thunderstorms developed near the center of Ashobaa on Monday, but vertical wind shear is still inhibiting intensification.  Ashobaa is moving over water where the Sea Surface Temperature (SST) is warm and there is sufficient energy in the upper ocean to promote intensification.  The circulation is extracting energy from the ocean and it is generating vigorous convection west of the center of circulation.  However, an upper level ridge over southern Asia is creating moderate easterly winds over the top of Ashobaa.  The resulting vertical wind shear is the reason why the strongest storms are west of the center.  Ashobaa will spend several more days in a thermodynamic environment that favors intensification and if the upper level winds lessen, it will intensify.  Eventually, when Ashobaa gets closer to land, the circulation will start to pull in drier air, which will weaken the tropical cyclone.

A ridge over India is steering Ashobaa toward the northwest.  A trough passing north of the Arabian Sea is expected to weaken the western end of the ridge and cause the tropical cyclone to turn more toward the north for a time.  Eventually, most models are forecasting that the ridge will rebuild and steer Ashobaa toward the west-northwest.   However, some models are still predicting that Ashobaa could move northward and make landfall on the northern coast of the Arabian Sea.  The spread in the guidance from the models makes the long-term track more uncertain.