Category Archives: Indian Ocean

Tropical Cyclone 01A Forms Over the Arabian Sea

A low level circulation formed within a larger area of thunderstorms over the Arabian Sea and the system was classified as Tropical Cyclone 01A.  At 11:00 p.m. EDT on Sunday the center of Tropical Cyclone 01A was located at latitude 18.0°N and longitude 67.5°E which put it about 490 miles (790 km) south of Karachi, Pakistan.  It was moving toward the north-northwest at 10 m.p.h. (17 km/h).  The maximum sustained wind speed was 45 m.p.h. (70 km/h) and there were gusts to 60 m.p.h. (75 km/h).  The minimum surface pressure was 994 mb.

Tropical Cyclone 01A is over warm Sea Surface Temperatures and there is sufficient energy in the upper ocean to support further intensification.  An upper level ridge over India is creating some easterly wind over the cyclone.  The strongest thunderstorms are occurring in the western half of the core of the cyclone.  The shear will inhibit intensification, but Tropical Cyclone 01A is likely to intensify during the next day or two.  Uncertainty about the future track of the cyclone also creates uncertainty about the longer term intensity forecast.

Tropical Cyclone 01A is moving northward around the western end of the ridge over India.  A trough farther to the north over Asia is expected to weaken the ridge and at that point the steering pattern will weaken.  Model guidance is inconsistent about the future track of the cyclone.  Some models forecast that Tropical Cyclone 01A will continue to move northward into Pakistan.  Other models predict that the cyclone could curve westward before it reaches Pakistan.  Thus, there is a high degree of uncertainty about the future track of Tropical Cyclone 01A.

Tropical Cyclone Quang Nearing the Coast of Western Australia

Tropical Cyclone Quang is weakening as it nears the coast of Western Australia.  At 11:00 p.m. EDT on Thursday the center of Tropical Cyclone Quang was located at latitude 20.5°S and longitude 112.1°E which put it about 160 miles northwest of Exmouth and about 210 miles north-northwest of Coral Bay, Australia.  Quang was moving toward the southeast at 14 m.p.h.  The maximum sustained wind speed was 100 m.p.h. and there were gusts to 120 m.p.h.  The minimum surface pressure was 969 mb.

An upper level ridge northeast of Tropical Cyclone Quang is generating strong northwesterly winds and vertical wind shear over it.  The wind shear in combination with cooler Sea Surface Temperatures is causing Quang to weaken.  The wind shear and rate of weakening could increase as the tropical cyclone moves farther south.

The upper level ridge is also steering Quang toward the southeast.  On the projected track Quang would make landfall on the coast of Western Australia between Exmouth and Cape Cuvier in about 12 hours.  The forecast weakening means that Quang is likely to be the equivalent of a tropical storm when it makes landfall.  It will bring some wind and locally heavy rain to parts of Western Australia as it moves inland.

 

Tropical Cyclone Quang Intensified Rapidly Into Equivalent of a Major Hurricane

Tropical Cyclone Quang intensified very rapidly on Wednesday and it reached an intensity equivalent to a major hurricane.  At 10:00 p.m. EDT on Wednesday the center of Tropical Cyclone Quang was located at latitude 17.0°S and longitude 109.2°E which put it about 460 miles northwest of Exmouth and about 610 miles north-northwest of Carnarvon, Australia.  Quang was moving south-southeast at 6 m.p.h.  The maximum sustained wind speed was 130 m.p.h. and there were gusts to 160 m.p.h.  The minimum surface pressure was 940 mb.

As Quang moved across very warm Sea Surface Temperatures (SSTs), the upper level winds eased enough to allow it to intensify very rapidly.  Thunderstorms around the eyewall transported mass upward and generated upper level divergence in all directions, which allowed the surface pressure to decrease quickly.  The decrease in surface pressure generated the rapid increase in wind speed.    Quang is a small tropical cyclone and small tropical cyclones can intensify and weaken more quickly than larger storms.  Quang may have peaked in intensity.  As it moves farther south it will move over cooler SSTs.  Upper level wind speeds will increase along the projected track creating more vertical wind shear.  In addition, it appears that some drier air may be entering the northwestern part of the circulation.  The combination of cooler SSTs, more wind shear and drier air is likely to weaken Quang significantly before it reaches the coast of Western Australia.

Quang is moving around the western end of a subtropical ridge.  As it moves toward higher latitudes, westerly winds are likely to steer it more toward the southeast.  Quang could be approaching the coast of Western Australia between Onslow and Denham in about 48 to 60 hours.

 

Tropical Cyclone Quang Forms Northwest of Australia

After several quiet weeks in the tropics a low level circulation developed in an area of thunderstorms northwest of Australia and the system was classified as Tropical Cyclone Quang (24S) on Tuesday.  At 10:00 p.m. EDT on Tuesday the center of Tropical Cyclone Quang was located at latitude 15.2°S and longitude 109.7°E which put it about 550 miles northwest of Exmouth, Australia.  Quang was moving toward the southwest at 6 m.p.h.  The maximum sustained wind speed was 45 m.p.h. and there were gusts to 65 m.p.h.  The minimum surface pressure was 997 mb.

Tropical Cyclone Quang developed over an area where the Sea Surface Temperatures (SSTs) are near 30°C.  A subtropical ridge to the east of Quang is generating some northeasterly winds over the circulation in the upper levels.  The resulting vertical wind shear is slowing the intensification of the circulation.  However, satellite imagery indicates that Quang is becoming more well organized.  A primary rainband has wrapped most of the way around the center of circulation and an eye may be forming.  Thunderstorms near the center of circulation are increasing the upper level outflow, especially on the southern side of Quang.  Further intensification is likely and Quang could reach hurricane intensity in 24 to 48 hours.  Eventually, when Quang moves farther south, it will move over cooler SSTs.  Vertical wind shear is also likely to increase at the same time, and Quang is likely to weaken as it approaches Western Australia.

Tropical Cyclone Quang is moving around the western end of the subtropical ridge.  As it reaches the western end of the ridge, it is likely to take a more southerly track on Wednesday.  By Thursday westerly winds are forecast to begin to steer Quang to the southeast.  On its projected track, Quang would approach the coast of Western Australia in about three days.  If it weakens as expected, Quang would bring some wind and rain when it moves across Western Australia.

Tropical Cyclone 15S Forms Over the Mozambique Channel

A low level circulation developed enough organization on the eastern side of a cluster of thunderstorms over the Mozambique Channel to be classified as a tropical cyclone on Thursday.  At 11:00 p.m. EST on Thursday the center of Tropical Cyclone 15S was located at latitude 16.6°S and longitude 42.3° which put it about 110 miles east-southeast of Mogincual, Mozambique and about 200 miles northwest of Maintirano, Madagascar.  It was moving toward the south-southeast at 5 m.p.h.  The maximum sustained wind speed was 40 m.p.h. and there were wind gusts to 50 m.p.h.  The minimum surface pressure was 996 mb.

Southeasterly winds in the upper levels are creating vertical wind shear and most of the stronger thunderstorms are on the western side of the center of circulation.  However, the tropical cyclone is over warm Sea Surface Temperatures and some intensification is possible.  If the upper level winds decrease, the more rapid intensification could occur.  A gradual intensification seems more likely over the short term.

A subtropical ridge of high pressure to the east of the tropical cyclone is steering it slowly to the south.  It is likely to move into a region of weak steering winds  between that ridge of high pressure and another ridge farther to the west.  As a result, the tropical cyclone could move slowly and erratically and even become stationary at times during the next day or two.  Eventually, a third ridge of high pressure is expected to develop to the north of the system and push it westward toward Madagascar.

The tropical cyclone could be a strong tropical storm or near hurricane intensity when it reaches Madagascar.  Some wind damage is possible, but the biggest threat appears to be from locally heavy rainfall and flooding.

 

Tropical Cyclone Glenda Forms South of Diego Garcia

A low level circulation consolidated quickly in a large area of thunderstorms over the south central Indian Ocean and the system was classified as Tropical Cyclone Glenda.  At 11:00 p.m. EST on Tuesday the center of Tropical Cyclone Glenda was located at latitude 17.3°S and longitude 69.8°E which put it about 670 miles south of Diego Garcia and about 1040 miles east-northeast of La Reunion.  Glenda was moving toward the west-southwest at 10 m.p.h.  The maximum sustained wind speed was 65 m.p.h. and there were gusts to 75 m.p.h.  The minimum surface pressure was 982 mb.

Glenda is over warm Sea Surface Temperatures and it has well developed upper level outflow.  The outflow is pumping out mass and the pressure has been decreasing steadily.  Glenda is like to remain in a favorable environment for another 48 hours.  It will likely reach hurricane intensity on Wednesday and it could become the equivalent of a major hurricane on Thursday.

Glenda is being steered to the west-southwest by a subtropical ridge located southeast of it.  This motion is likely to continue for another 24 to 36 hours.  When it approaches the western end of the ridge, it will turn more toward the south.  The projected track keeps Glenda well south of Diego Garcia and has it turning southward well to the east of La Reunion.  As a result, Glenda poses no current threat to any land area.

 

Tropical Cyclone Fundi Forms Near the Southwest Coast of Madagascar

A well defined center of circulation developed in the lower levels of an area of thunderstorms near the southwest coast of Madagascar and the system was designated as Tropical Cyclone Fundi.  At 5:00 p.m. EST on Friday the center of Tropical Cyclone Fundi was located at latitude 22.8°N and longitude 42.9°E which put it about 60 miles west of Toliara, Madagascar.  Fundi was moving toward the southeast at 8 m.p.h.  The maximum sustained wind speed was 40 m.p.h. and there were gusts to 50 m.p.h.  The minimum surface pressure was 999 mb.

The environment around Fundi contains some factors that would support intensification and other factors that would inhibit intensification.  It is over warm Sea Surface Temperatures and there is well developed outflow in the upper levels.  Those factors would favor intensification.  However, the center of circulation is very close to the coast of Madagascar and part of the circulation is over land.  Interaction with land will inhibit future intensification.  If the center of circulation remains over the water, then some intensification is possible during the next day or two.  If the center of circulation moves over southern Madagascar, then it will weaken.  Eventually, Fundi will move poleward and encounter colder Sea Surface Temperatures and more vertical wind shear.

 

A subtropical ridge located east of Fundi is steering the tropical cyclone toward the southeast.  The ridge is expected to continue to steer it toward the southeast or south in the short term.  As Fundi moves farther south, it will begin to encounter upper level westerly winds which will turn it more toward the east.

Tropical Cyclone Eunice Reaches the Equivalent of a Category 5 Hurricane

Tropical Cyclone Eunice strengthened rapidly on Thursday as it moved over the South Indian Ocean and it has attained an intensity equivalent to that of a Category 5 hurricane on the Saffir-Simpson Scale.  At 8:00 p.m. EST on Thursday the center of Eunice was located at latitude 17.7°S and longitude 67.7°E, which put it about 780 miles south-southwest of Diego Garcia.  It was moving toward the south-southeast at 10 m.p.h.  The maximum sustained wind speed was 160 m.p.h. and it was estimate that there were wind gusts to 185 m.p.h.  The minimum surface pressure was 918 mb.

Eunice has been in an environment very conducive for rapid intensification.  It has moved over warm Sea Surface Temperatures and upper level winds have been quite light.  As a result deep convection has been ongoing around the core of the circulation and upper level outflow has pumped out large quantities of mass.  Those processes caused the pressure to decrease rapidly and the wind speeds increased in a corresponding manner.  Eunice will remain in a favorable environment for another day or so.  After that time it will move to a higher latitude, which will place it in an area of lower Sea Surface Temperatures and more vertical wind shear.   Eunice is likely to weaken without threatening any land area.

 

Tropical Cyclone Chedza Crossing Madagascar

Tropical Cyclone Chedza is moving across the central portion of Madagascar.  At 3:00 p.m. EST the center of Chedza was located at latitude 20.4°N and longitude 44.7°E which put it near Belo Tsiribihina.  It was moving toward the east-southeast at 10 m.p.h.  The maximum sustained wind speed was 45 m.p.h. and there were gusts to 55 m.p.h.  The minimum surface pressure was 996 mb.

Low vertical wind shear and warm Sea Surface Temperatures created an environment favorable for intensification and Chedza strengthened prior to making landfall in western Madagascar.  Satellite imagery indicated an eyelike feature formed and it is possible that Chedza may have reached hurricane intensity before landfall.  The terrain of Madagascar is weakening the lower portions of the circulation and that trend should continue while the center is over land.  It is possible that Chedza could strengthen after the center moves back over water east of Madagascar.

Tropical Storm Chedza Forms West of Madagascar

The tropical cyclone closest to land is Tropical Cyclone Chedza.  A cluster of thunderstorms meandering over the Mozambique Channel organized rapidly on Thursday and developed into Tropical Cyclone Chedza.  At 9:00 p.m. EST on Thursday the center of Chedza was located at latitude 19.1°S and longitude 42.4°E which put it about 140 miles west-northwest of Belo Tsiribihina, Madagascar.  It was moving toward the east at 6 m.p.h.  The maximum sustained wind speed was 45 m.p.h. and there were gusts to 55 m.p.h.  The minimum surface pressure was 996 mb.

Chedza is over warm Sea Surface Temperatures and the upper level winds are relatively light.  Further intensification is likely until Chedza makes landfall on Friday.  It is expected to weaken as it crosses Madagascar.  Some re-intensification may be possible after the center emerges over the Indian Ocean east of Madagascar.  Potential risks include locally heavy rainfall and flooding.

A near equatorial ridge is steering Chedza eastward.  It is expected to make landfall in 12 to 18 hours.  The ridge is expected to steer Chedza toward the east-southeast as it crosses Madagascar.