Tag Archives: IO04

Tropical Cyclone 04B Develops Over Northern Bay of Bengal

Tropical Cyclone 04B developed over the northern Bay of Bengal on Friday.  The circulation around an area of low pressure southeast of India strengthened on Friday and the Joint Typhoon Warning Center (JTWC) designated the system as Tropical Cyclone 04B.  Data from a scatterometer on a satellite indicated there were winds to 45 m.p.h. (75 km/h) in the western part of the circulation.  The Indian Meteorological Department was classifying the low pressure system as a depression and that was why it did not have a name.

At 4:00 p.m. EDT on Friday the center of Tropical Cyclone 04B was located at latitude 18.7°N and longitude 86.9°E which put it about 340 miles (550 km) southwest of Kolkata, India.  It was moving toward the north at 18 m.p.h. (29 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 994 mb.

Although there was a well defined low level center of circulation, the rest of the circulation of Tropical Cyclone 04B was not particularly well organized.  There were no strong thunderstorms near the center of circulation.  The stronger thunderstorms were occurring in a rainband 80 miles (130 km) northeast of the center of circulation.  Other bands revolving around the center consisted primarily of low clouds and showers.

Tropical Cyclone 04B is moving through an environment that is only marginally favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 28°C.  So, there is enough energy in the upper ocean to support intensification, but that is about the only factor favorable for intensification.  Tropical Cyclone 04B is moving underneath the western end of an upper level ridge.  The ridge is producing southeasterly winds which are blowing across the top of the circulation.  Those winds are also causing moderate vertical wind shear and the shear is probably the reason why the band of thunderstorms is displaced northeast of the center of circulation.  It also appears that the western side of the circulation of Tropical Cyclone 04B is also pulling some drier air from over India into the system.  Tropical Cyclone 04B is unlikely to intensify due to the effects of moderate wind shear and drier air.

The upper level ridge is steering Tropical Cyclone 04B toward the north.  On its anticipated track Tropical Cyclone 04B could make landfall near Kolkata in 24 to 30 hours.  The primary risk is locally heavy rain which could cause flooding.  The rain is likely to reach northeastern India a few hours before the center of circulation makes landfall.

Tropical Cyclone Nada Develops Near Sri Lanka

Tropical Cyclone Nada developed over the Bay of Bengal near Sri Lanka.  At 10:00 a.m. EDT on Wednesday the center of Tropical Cyclone Nada was located at latitude 10.1°N and longitude 83.5°E which put it about 295 miles (475 km) east-southeast of Chennai, India.  Nada was moving toward the west-northwest at 14 m.p.h. (23 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 997 mb.

Microwave satellite imagery indicates that Tropical Cyclone Nada has a well organized, circular low level circulation.  However, most of the thunderstorms are occurring in bands southwest of the center and north of the center.  There are mostly low clouds and showers in the circular bands south and east of the center of circulation.  An upper level ridge over the northern Bay of Bengal is producing easterly winds which are causing moderate vertical wind shear.  The upper level easterly flow is inhibiting the development of thunderstorms east of the center of Tropical Cyclone Nada and those winds may be tilting the circulation toward the west.

The environment surround Tropical Cyclone Nada consists of factors that are favorable for intensification and factors that are unfavorable.  Tropical Cyclone Nada is moving over water where the Sea Surface Temperature is near 29°C.  So, there is sufficient energy in the upper ocean to support intensification.  However the easterly winds in the upper levels are restricting upper level divergence to the east of the tropical cyclone.  Moderate vertical wind shear will limit intensification unless the upper level winds weaken.  If the upper level winds do weaken, then Nada could strengthen given its well developed low level circulation.  Tropical Cyclone Nada only has about 24 to 30 hours before it reaches the coast of India and it will start to weaken once it moves over land.

A subtropical ridge north of Nada is steering the tropical cyclone toward the west-northwest and that general motion is expected to continue.  On its anticipated track the center of Tropical Cyclone Nada will pass north of Sri Lanka and it will approach the southeast coast of India in 24 to 30 hours.  Nada is likely to make a landfall south of Cheannai, India near Pondicherry.  Tropical Cyclone Nada is expected to continue to move to the west and it could emerge over the Arabian Sea in two or three days.

Tropical Cyclone Nada will bring gusty winds and locally heavy rain to northern Sri Lanka and southern India.  Locally heavy rain could cause flooding and mudslides in parts of northern Sri Lanka and Tamil Nadu, Kerala and Karnataka states in India.

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.