Category Archives: Indian Ocean

Tropical Cyclone Kate Intensfies Rapidly over Southeastern Indian Ocean

Favorable oceanic and atmospheric conditions allowed Tropical Cyclone Kate to intensify very rapidly on Friday.  The maximum sustained wind speed increased from 50 m.p.h. to 120 m.p.h. during a 24 hour period.  At 10:00 p.m. EST on Friday the center of Tropical Cyclone Kate was located at latitude 12.9°S and longitude 93.8°E which put it about 215 miles west-southwest of the Cocos Islands and about 2450 miles west of Darwin, Australia.  Kate was moving toward the southwest at 5 m.p.h., which was taking it away from the Cocos Islands.  The maximum sustained wind speed was 120 m.p.h. which made Kate the equivalent of a Category 3 hurricane on the Saffir-Simpson Scale and it was estimated that there were gusts to 150 m.p.h.

Although there were upper level winds blowing from the east, which created some wind shear over Kate, it was able to develop strong upper level outflow which produced rapid intensification.  Some satellite imagery shows that the wind shear is causing the strongest thunderstorms to be on the western side of the center of circulation.  Recent visible and infrared satellite imagery show evidence of an circular eye developing.  Some further intensification is possible during the next 24 hours as long as the upper level outflow is able to pump out sufficient mass.  Eventually, as Kate moves toward higher latitudes the wind shear will increase and the Sea Surface Temperatures will decrease.  The more hostile environment will weaken the tropical cyclone and the weakening could be almost as rapid as the intensification was.

Kate is expected to continue to be steered in a generally southwesterly direction in the short term by a subtropical ridge.  As it moves farther south, it will begin to be affected by westerly midlatitude flow and it will start to recurve more toward the south.  Kate passed over the Cocos Islands earlier this week as a tropical storm.  It is expected to dissipate over the Indian Ocean and not affect any other land areas as a tropical cyclone.

 

Tropical Cyclone Nilofar Weakening Rapidly Over the Arabian Sea

Strong southwesterly winds in the upper troposphere are generating vertical wind shear over the top of Tropical Cyclone Nilofar.  The wind shear is blowing the upper part of Nilofar’s circulation northeast of the low level center of circulation and causing the tropical cyclone to weaken rapidly.  At 8:00 a.m. EDT on Thursday the center of Tropical Cyclone Nilofar was located at latitude 20.3°N and longitude 64.5°E which put it about 350 miles south-southwest of Karachi, Pakistan and about 550 miles west of Mumbai, India.  Nilofar was moving toward the northeast at 7 m.p.h.  The maximum sustained wind speed was 50 m.p.h. and there were wind gusts to 65 m.p.h.

An upper level trough to the northwest of Nilofar is pushing strong southwesterly winds over the top of it.  There is evidence on satellite imagery that the wind shear may be strong enough to detach the upper portion of Nilofar’s circulation and transport it northeast of the low level center.  When the upper portion of the circulation is sheared away and detached, it removes the warm core and eliminates the ability of the cyclone to pump out the mass which is converging on the low level center.  If the wind shear were to lessen, Nilofar might be able to re-establish the link between the circulation in the lower and upper levels.  However, the wind shear is not expected to diminish and so Nilofar is likely to continue to weaken.  It may no longer meet the criteria to be classified as a tropical cyclone in another 24-48 hours.

The lower level circulation of NIlofar is expected to continue toward the northeast in the short term.   If the lower level circulation becomes shallow enough, then the southwesterly winds in the upper levels could blow over the top of it.  If that happens, then the lower level circulation could drift in the northern Arabian Sea until it spins down.  Some of the moisture associated with the circulation of Nilofar could get transported into parts of eastern Pakistan and western India where it could enhance precipitation.

 

Tropical Cyclone Nilofar Intensifies Into the Equivalent of a Major Hurricane

Light winds in the upper troposphere allowed the circulation around Tropical Cyclone Nilofar to pump out sufficient mass to enable it to intensify into the equivalent of a Major Hurricane.  At 8:00 a.m. EDT on Tuesday the center of Nilofar was located at latitude 16.8°N and longitude 61.8°E which put it about 315 miles southeast of Masirah Island, about 650 miles south-southwest of Karachi, Pakistan and about 740 miles west of Mumbai, India.  Nilofar was moving toward the north at 11 m.p.h.  The maximum sustained wind speed was 135 m.p.h. and there were wind gusts estimated to be 160 m.p.h.

The environment around Nilofar is capable of supporting an intense tropical cyclone, which is what Nilofar has become.  The upper level winds are light, which has allowed upper level divergence to spread the air in all directions.  In addition, the upper level outflow from Nilofar has interacted with surrounding weather systems to create outflow channels to the northeast and to the southwest.  The favorable atmospheric environment combined with warm Sea Surface Temperatures, which are supplying plenty of energy to Nilofar, has produced a strong tropical cyclone.  Nilofar could intensify further, although it is at the intensity where eyewall replacement cycles could begin to cause fluctuations in intensity.

Nilofar is moving around the western end of a subtropical high pressure system which is steering it to the north.  An upper level trough in the westerly flow north of Nilofar will eventually turn it toward the northeast.  Nilofar could threaten parts of Pakistan and India by the end of the week.  However, the southwesterly winds in the upper level trough will also generate more wind shear and Nilofar could start to weaken rapidly when it moves toward the coast of South Asia.

 

The Winds in Tropical Cyclone Nilofar Reach Hurricane Intensity

Tropical Cyclone Nilofar (Tropical Cyclone 04A) intensified on Sunday and it is now the equivalent of a hurricane.  At 8:00 p.m. EDT on Sunday the center of Nilofar was located at latitude 14.8°N and longitude 62.8°E, which put it about 470 miles southeast of Masirah Island, about 750 miles south-southwest of Karachi, Pakistan and about 720 miles west-southwest of Mumbai, India.  Nilofar was moving toward the north-northwest at 5 m.p.h.  The maximum sustained wind speed was 75 m.p.h. and there were wind gusts to 90 m.p.h.

Well developed upper level outflow was pumping out mass and Nilofar intensified steadily on Sunday.  The upper level outflow remains well developed and there appear to be outflow channels to the southwest and northeast.  So, further intensification is possible in the shorter term.  Nilofar is expected to move northward and eventually stronger westerly winds will increase the wind shear and start to weaken the tropical cyclone.

Nilofar has been moving slowly toward the northwest.  It is likely to continue moving northward during the next 24-48 hours.  When Nilofar gets farther north, southwesterly winds on the east side of an upper level trough will turn it more toward the northeast.  Nilofar could eventually make a landfall in Pakistan or India, but the stronger upper level winds will weaken the circulation before it reaches the coast.

 

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.

Tropical Cyclone Hudhud About to Make Landfall in India

The center of Tropical Cyclone Hudhud is getting very near the coast of India.  At 8:00 p.m. EDT the center was located at latitude 17.2°N and longitude 84.2°E which put it about 70 miles east-southeast of Visakhapatnam, India.  Hudhud was moving toward the north-northwest at 8 m.p.h.  It had maximum sustained winds to 125 m.p.h. and there were gusts to 155 m.p.h.

Hudhud is likely to bring strong winds and locally heavy rainfall to parts of eastern India as it moves inland during the next 24 hours.  The center will pass near the city of Visakhapatnam which has a population of over two million people.  Hudhud could also generate a significant storm surge  along the coast.

 

Tropical Cyclone Hudhud Intensifying As It Get Closer to India

Tropical Cyclone Hudhud continues to move toward the eastern coast of India and it is not intensifying more rapidly.  At 2:00 p.m. EDT the center of Hudhud was located at latitude 15.9°N and longitude 86.5°E, which put it about 230 miles east-southeast of Visakhapatnam, India.  Hudhud was moving toward the northwest at 7 m.p.h.  The maximum sustained wind speed was 100 m.p.h. and there were gusts to 120 m.p.h.

A high pressure system located northeast of Hudhud is likely to continue to steer it toward the west-northwest or northwest until it reaches India.  Wind shear over Hudhud has decreased and the tropical cyclone is intensifying and it could intensify steadily until it makes landfall.  Hudhud will approach the coast of India near Visakhapatnam in about 36 hours and it will be a strong tropical cyclone when it gets there.  In addition to strong winds and heavy rain, Hudhud could also produce a significant storm surge along the coast.