Tag Archives: Oman

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 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 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.

Tropical Cyclone Forms Over the Arabian Sea

A banded structure developed within an area of thunderstorms over the Arabian Sea and it has been classified as a tropical cyclone.  At 8:00 p.m. EDT on Saturday the center of Tropical Cyclone 04A was located at latitude 14.1°N and longitude 63.0°E which put it about 515 miles south-southeast of Masirah Island.  Tropical Cyclone 04A was moving toward the north at 5 m.p.h.  The maximum sustained wind speed was 40 m.p.h. and there were gusts to 50 m.p.h.

The tropical cyclone had been moving toward the northeast, but it appears to be turning more to northwest in response to a strengthening ridge of high pressure.  It is expected to move toward the northwest during the next 36-48 hours.  As the tropical cyclone approaches Oman, an upper level trough is expected to turn it toward the northeast.  There is some spread in the model guidance about when and where the turn toward the northeast will occur.  Therefore there is greater than normal uncertainty about the track forecast at longer time periods.

Upper level divergence is pumping out mass toward the northeast and southwest of the circulation.  As a result the surface pressure should fall and the tropical cyclone is expected to intensify during the next 48-72 hours.  Winds could reach hurricane force as the tropical moves in the general direction of Oman.