Category Archives: Indian Ocean

Tropical Cyclone Riley Strengthens to Equivalent of Hurricane/Typhoon

Tropical Cyclone Riley strengthened into the equivalent of a hurricane/typhoon on Friday.  At 4:00 p.m. EST on Friday the center of Tropical Cyclone Riley was located at latitude 17.2°S and longitude 116.9°E which put it about 415 miles (675 km) north-northeast of Learmonth, Australia.  Riley was moving toward the west at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 976 mb.

Tropical Cyclone Riley strengthened, but the distribution of thunderstorms was asymmetrical.  The strongest winds were occurring in a band the curled around the northern half of the center of circulation.  Storms in the band were generating upper level divergence which was pumping mass away from the tropical cyclone.  Other bands of showers and thunderstorms were present in the western half of the circulation, but the bands in the eastern half of Tropical Cyclone Riley consisted primarily of showers and lower clouds.  Winds to hurricane/typhoon force extended out about 35 miles (55 km) from the center of circulation and they were occurring mainly north of the center of Riley.  Winds to tropical storm force extended out about 130 miles (215 km) from the center.

Tropical Cyclone Riley was moving around the northwestern part of an upper level ridge.  The ridge was producing easterly winds which were blowing toward the top of the circulation.  Those winds appeared to converge with the upper level divergence on the east side of Riley to produce sinking motion in that part of the tropical cyclone.  The sinking motion was bringing drier air to the lower levels and it appeared to suppressing convection in that region.

Tropical Cyclone Riley may be close to its peak intensity.  Riley is currently over water where the Sea Surface Temperature is near 28°C, but it will move over cooler water during the next few days.  The upper level ridge will continue to produce easterly winds which will blow toward the top of the circulation.  Those winds could strengthen which would cause more vertical wind shear.  Riley could intensify during the next 24 hours, but it is more likely to gradually weaken during the next two or three days.

The ridge will steer Tropical Cyclone Riley toward the west-southwest during the next few days.  On its anticipated track Riley will remain north of the coast of Western Australia,  However, watches and warnings are in effect for portions of the coast in case the Tropical Cyclone Riley moves more toward the south.  A Tropical Cyclone Warning is in effect for the portion of the coast from Whim Creek to Onslow including Karratha and Dampier.  A Tropical Cyclone Watch is in effect from Onslow to Exmouth.

Elsewhere around Australia, a Tropical Low was dropping heavy rain over portions of northern Queensland.  At 1:00 p.m. EST the center of the Tropical Low was located at latitude 13.8°S and longitude 141.3°E which put it about 80 miles (125 km) north-northwest of Pormpuraaw, Australia.  It was moving toward the southeast at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1002 mb.  Locally heavy rain could cause floods in parts of northern Queensland.

Tropical Low Prompts Warning for Northern Queensland

A tropical low over the Gulf of Carpentaria prompted the issuance of warnings and watches for northern Queensland on Thursday.  A Tropical Cyclone Warning was in effect for the portion of the coast from Mapoon to Karumba.  A Tropical Cyclone Watch was in effect for the portion of the coast from Karumba to the border between Queensland and the Northern Territory including Mornington Island.

At 7:00 p.m. EST on Thursday the center of the tropical low was located at latitude 13.0°S and longitude 139.9°E which put it about 135 miles (220 km) west of Weipa, Australia.  It was moving toward the north at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1002 mb.

The circulation around the tropical low exhibited more organization on Thursday.  A band of showers and thunderstorms wrapped around the western and northern sides of the center of circulation.  Other bands of showers and thunderstorms were developing over the Gulf of Carpentaria.  Storms near the center of circulation began to generate upper level divergence which was pumping mass away in outflow channels to the northwest and southeast of the tropical low.

The tropical low will move through an environment favorable for intensification.  It will move over water where the Sea Surface Temperature is near 30°C.  The tropical low will be in an area where the upper level winds are weaker and the vertical wind shear will be limited.  The tropical low is likely to intensify during the next 24 to 36 hours and it is forecast to become a named tropical cyclone.

The tropical low is under the northeastern portion of an upper level low.  It is in a small region where the steering winds are weaker and the tropical low meandered over the eastern Gulf of Carpentaria on Thursday.  Northerly winds blowing around the upper level low are forecast to steer the tropical low toward the south during the next day or two.  On its anticipated path the tropical low is expected to move over the eastern Gulf of Carpentaria near the coast of Queensland.  If the tropical low follow its anticipated track, it will make landfall on the south coast of the Gulf of Carpentaria in about 48 hours.  However, any eastward deviation would bring the tropical low inland over Queensland much sooner.

Elsewhere, Tropical Cyclone Riley strengthened northwest of Australia.  At 7:00 p.m. EST on Thursday the center of Tropical Cyclone Riley was located at latitude 16.5°S and longitude 118.8°E which put it about 265 miles (425 km) north of Port Hedland, Australia.  Riley was moving toward the west at 4 m.p.h. (6 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 985 mb.  A Tropical Cyclone Watch was in effect for the portion of the coast from Whim Creek to Onslow, Australia including Karratha and Dampier.

Tropical Cyclone Riley Forms West of Australia

Tropical Cyclone Riley formed west of Australia on Wednesday.  At 4:00 p.m. EST on Wednesday the center of Tropical Cyclone Riley was located at latitude 16.7°S and longitude 121.2°E which put it about 110 miles (175 km) northwest of Broome, Australia.  Riley was moving toward the west-southwest at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 997 mb.

The circulation around a tropical low off the coast of Western Australia strengthened on Wednesday and the Australian Bureau of Meteorology designated the system as Tropical Cyclone Riley.  A band of thunderstorms wrapped clockwise from northwest to southeast around the center of circulation.  Additional bands of showers and thunderstorms were developing around the western side of the circulation which was over the open water of the south Indian Ocean.  The bands on the eastern side of the circulation were weaker, but portions of those bands were still over Western Australia.  Thunderstorms around the center of circulation were generating upper level divergence which was pumping mass away from the tropical cyclone.

Tropical Cyclone Riley will move through an environment favorable for intensification during the next several days.  Riley will move over water where the Sea Surface Temperature is near 30°C.  It will move through an area where the upper level winds are weak and there will not be much vertical wind shear.  Tropical Cyclone Riley is likely to intensify steadily and it could intensify rapidly once an eye forms and the inner core is well developed.  Tropical Cyclone Riley is likely to strengthen into the equivalent of a hurricane/typhoon within 24 to 36 hours.

Tropical Cyclone Riley will move along the northwestern edge of a subtropical ridge during the next 48 to 72 hours.  The ridge will steer Riley in a general west-southwesterly direction.  On its anticipated track Tropical Cyclone Riley will move parallel to the coast of Western Australia.  However, a southward deviation of the track could bring Riley closer to the coast.

Tropical Cyclone Desmond Brings Wind and Rain to Mozambique

Tropical Cyclone Desmond brought wind and rain to Mozambique on Monday.  At 4:00 p.m. EST on Sunday the center of Tropical Cyclone Desmond was located at latitude 18.8°S and longitude 36.3°E which put it about 25 miles (40 km) west of Conceicao, Mozambique.  Desmond was moving toward the west-northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1000 mb.

Tropical Cyclone Desmond made landfall in Mozambique near Ponta Timbue on Monday.  Thunderstorms developed on the western side of the circulation where the winds were blowing toward the land.  Those thunderstorms were dropping heavy rain over parts of Mozambique.  The strongest winds were occurring along the coast of Mozambique and over the Mozambique Channel.  Winds to tropical storm force extended out about 100 miles (160 km) on the eastern side of Tropical Cyclone Desmond.  Wind speeds were slower over land.

Tropical Cyclone Desmond will move around the eastern end of a subtropical high pressure system over southern Africa.  The high will steer Desmond toward the north-northwest.  On its anticipated track Tropical Cyclone Desmond will move farther inland over the Zambezi River toward southern Malawi.  Desmond will drop locally heavy rain over parts of the lower Zambezi River basin and flooding could occur in some locations.

Tropical Cyclone Desmond Forms Over Mozambique Channel

Tropical Cyclone Desmond formed over the Mozambique Channel on Sunday.  At 4:00 p.m. EST on Sunday the center of Tropical Cyclone Desmond was located at latitude 21.3°S and longitude 39.0°E which put it about 250 miles (400 km) south-southeast of Quelimane, Mozambique.  Desmond was moving toward the north at 6 m.p.h. (10 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 997 mb.

Thunderstorms developed closer to the center of a low pressure system over the Mozambique Channel on Sunday and the system was designated Tropical Cyclone Desmond.  The distribution of thunderstorms around Desmond was very asymmetrical.  Most of the stronger thunderstorms were occurring in bands southeast of the center of circulation.  Bands in other parts of the circulation consisted of showers and lower clouds.  An upper level trough just southeast of Africa was producing northwesterly winds which were blowing toward the top of Tropical Cyclone Desmond.   Those winds were causing moderate vertical wind shear and they were probably the reason for the asymmetrical distribution of thunderstorms.

Tropical Cyclone Desmond will move through an environment somewhat favorable for intensification during the next 24 to 36 hours.  Desmond will move over water where the Sea Surface Temperature is near 29°C.  The upper level trough is forecast to move eastward and the vertical wind shear could decrease.  Tropical Cyclone Desmond could strengthen when the shear decreases, if it is still over water.

Tropical Cyclone Desmond will move around the eastern end of a subtropical ridge in the middle levels over southern Africa.  The ridge should steer Desmond in a north-northwesterly direction.  On its anticipated track Tropical Cyclone Desmond will move toward Mozambique and it could make landfall within 36 hours.  However, there is another low pressure system near northern Madagascar.  If the circulations of the two low pressure systems interact, then Desmond could be pulled farther to the north.

Tropical Storm Pabuk Brings Wind and Rain to Southern Thailand

Tropical Storm Pabuk brought wind and rain to southern Thailand on Friday.  At 5:00 p.m. EST on Friday the center of Tropical Storm Pabuk was located at latitude 8.7°N and longitude 98.5°E which put it about 60 miles (95 km) northeast of Phuket, Thailand.  Pabuk was moving toward the west-northwest at 10 m.p.h. (16 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 997 mb.

Tropical Storm Pabuk made landfall near Sichon in southern Thailand.  Pabuk brought gusty winds to much of the Isthmus of Kra.  It also dropped heavy rain over parts of southern Thailand.  Tropical Storm Pabuk weakened when it crossed the Isthmus of Kra, but the core of the circulation appears to have remained intact.  Pabuk is moving over the Andaman Sea and it still has a well defined low level center of circulation.  Several bands of showers and thunderstorms are revolving around the core of the tropical storm.  Additional bands of showers and thunderstorms are located in the northeastern part of the circulation which is over the Gulf of Thailand.

Tropical Storm Pabuk will move into an environment favorable for intensification during the next 24 to 36 hours.  Pabuk will move over water where the Sea Surface Temperature is near 28°C.  An upper level ridge over the Western North Pacific Ocean will produce southeasterly winds which will blow toward the top of the circulation.  Those winds will cause moderate vertical wind shear, which will inhibit intensification.  However, the wind shear may not be strong enough to prevent Tropical Storm Pabuk from strengthening.

Tropical Storm Pabuk will continue to move around the western end of the ridge over the Western North Pacific Ocean.  The ridge will steer Pabuk toward the west-northwest for another 24 to 36 hours.  Pabuk will turn more toward the north when it reaches the western end of the ridge.  On its anticipated track Tropical Storm Pabuk will reach the Andaman Islands in about 36 hours.

Elsewhere over the Western North Pacific Ocean, Tropical Depression 01W formed southeast of the Marshall Islands.  At 4:00 p.m. EST on Friday the center of Tropical Depression 01W was located at latitude 4.9°N and longitude 174.0°E which put it about 250 miles (400 km) southeast of Majuro, Marshall Islands.  It was moving toward the northwest at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1004 mb.  Tropical Depression 01W is forecast to move toward the west-northwest and strengthen.  On its anticipated track it could move toward Majuro, Kwajalein, Ujelang, and the Marianas.

Tropical Cyclone Cilida Passes East of Mauritius

Strong Tropical Cyclone Cilida passed east of Mauritius on Saturday night.  At 10:00 p.m. EST on Saturday the center of Tropical Cyclone Cilida was located at latitude 20.2°S and longitude 60.3°E which put it about 170 miles (275 km) east of Port Louis, Mauritius.  Cilida was moving toward the south-southeast at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 145 m.p.h. (230 km/h).  The minimum surface pressure was 953 mb.

Tropical Cyclone Cilida was being steered to the south-southeast between an upper level trough near Madagascar and a subtropical ridge over the South Indian Ocean.  Those weather systems steered Cilida east of Mauritius.  Northwesterly winds blowing on the eastern side of the upper level trough were causing vertical wind shear.  Tropical Cyclone Cilida was weakening, but it was still the equivalent of a major hurricane.  There was a circular eye at the center of Cilida.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Several bands of showers and thunderstorms were revolving around the core of Tropical Cyclone Cilida.

Winds to hurricane/typhoon force extended out about 45 miles (75 km) from the center of Tropical Cyclone Cilida.  Winds to tropical storm force extended out about 115 miles (185 km) from the center.  Cilida passed far enough to the east of Mauritius that the strongest winds remained offshore.  A weather station at Belle Mare on the east coast of Mauritius reported a maximum wind speed of 38 m.p.h. (61 km/h).  An automated weather station on Signal Mountain reported a maximum wind speed of 49 m.p.h. (79 km/h).  Tropical Cyclone Cilida probably brought winds to tropical storm force to Mauritius, especially at higher elevations.

The stronger rainbands around Tropical Cyclone Cilida also passed east of Mauritius.  Cilida dropped light rain over most of Mauritius.  Heavier rain did fall over locations where the wind blew up the slopes of ridges and mountains.  1.44 inches (36.6 mm) of rain fell at Mon Bois and 1.31 inches (33.4 mm) fell at Mare Aux Vacoas.

The upper level trough over Madagascar will continue to steer Tropical Cyclone Cilida toward the south-southeast.  On its anticipated track Cilida will move farther away from Mauritius.  Tropical Cyclone Cilida will continue to weaken as it moves over cooler Sea Surface Temperatures and the vertical wind shear increases.

Powerful Tropical Cyclone Cilida Strengthens to Equivalent of Cat. 4 Hurricane

Powerful Tropical Cyclone Cilida strengthened to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale on Friday.  At 4:00 p.m. EST on Friday the center of Tropical Cyclone Cilida was located at latitude 15.9°S and longitude 57.8°E which put it about 310 miles (505 km) north of Port Louis, Mauritius.  Cilida was moving toward the south at 6 m.p.h. (10 km/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 931 mb.

The circulation of Tropical Cyclone Cilida was very well organized.  A circular eye was at the center of circulation.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Several bands of showers and thunderstorms were revolving around the core of Tropical Cyclone Cilida.  Storms around the core were generating strong upper level divergence which was pumping mass away from the tropical cyclone.

The circulation around Tropical Cyclone Cilida was relatively small.  Winds to hurricane/typhoon force extended out about 35 miles (55 km) from the center of circulation.  Winds to tropical storm force only extended out about 95 miles (155 km) from the center.  The Hurricane Intensity Index (HII) for Tropical Cyclone Cilida was 31.6.  The Hurricane Size Index (HSI) was 11.0 and the Hurricane Wind Intensity Size Index (HWISI) was 42.6.

Tropical Cyclone Cilida may have peaked in intensity, but it will move through an environment capable of supporting a strong tropical cyclone for another 24 to 36 hours.  Cilida will move over water where the Sea Surface Temperature is near 28°C for about another 24 hours.  Then it will start to move over colder waters.  Tropical Cyclone Cilida will move toward the upper level westerly winds in the middle latitudes and the vertical wind shear will increase in about 36 hours.  When Cilida moves over colder water and under stronger upper level winds, it will weaken more quickly.

Tropical Cyclone Cilida is moving around the western end of a subtropical ridge over the South Indian Ocean.  The ridge will start to steer Cilida toward the southeast on Saturday.  On its anticipated track, the center of Tropical Cyclone Cilida could be a little northeast of Mauritius in about 24 hours.  It will still be a powerful tropical cyclone at that time.

Elsewhere over the South Indian Ocean, Tropical Cyclone Kenanga continued to weaken well to the southeast of Diego Garcia.  At 4:00 p.m. EST on Friday the center of Tropical Cyclone Kenanga was located at latitude 16.3°S and longitude 78.5°E which put it about 760 miles (1225 km) southeast of Diego Garcia.  Kenanga was moving toward the west at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 982 mb.

Tropical Cyclone Cilida Quickly Intensifies Into Equivalent of a Major Hurricane

Tropical Cyclone Cilida quickly intensified into the equivalent of a major hurricane north of Mauritius on Thursday.  At 10:00 p.m. EST on Thursday the center of Tropical Cyclone Cilida was located at latitude 14.5°N and longitude 58.0°E which put it about 410 miles (660 km) north of Port Louis, Mauritius.  Cilida was moving toward the southwest at 8 m.p.h. (13 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 949 mb.

Tropical Cyclone Cilida intensified quickly on Thursday.  A symmetrical, circular eye appeared more distinctly on satellite images.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Several bands of showers and thunderstorms were revolving around the core of Tropical Cyclone Cilida.  Storms near the core of Cilida generated strong upper level divergence which pumped mass away from the tropical cyclone.  The removal of mass allowed the surface pressure to decrease rapidly and the wind speed increased in response to a larger pressure gradient force.  Winds to hurricane/typhoon force extended out about 35 miles (55 km) from the center of circulation.  Winds to tropical storm force extended out about 120 miles (195 km) from the center.

Tropical Cyclone Cilida will move through an environment favorable for strong tropical cyclones during the next 24 to 36 hours.  Cilida will move over water where the Sea Surface Temperature is near 28°C.  It will move through an area where the upper level winds are weak and there will be little vertical wind shear.  Tropical Cyclone Cilida will get stronger during the next day or so unless an eyewall replacement cycle begins.  If a rainband wraps around the existing eyewall, then an eyewall replacement cycle could cause Cilida to weaken.

Tropical Cyclone Cilida will move around the western end of a subtropical ridge over the South Indian Ocean.  The ridge is likely to steer Cilida toward the southwest for another 12 hours or so.  Tropical Cyclone Cilida will move more toward the south when it reaches the western end of the ridge.  In 36 to 48 hours Cilida will begin to be affected by the westerly winds in the middle latitudes and those winds will start to steer the tropical cyclone toward the southeast,  On its anticipated track Tropical Cyclone Cilida could approach Mauritius in about 36 hours.

Elsewhere over the South Indian Ocean Tropical Cyclone Kenanga weakened slowly well to the southeast of Diego Garcia.  At 10:00 p.m. EST on Thursday the center of Tropical Cyclone Kenanga was located at latitude 16.2°S and longitude 80.2°E which put it about 825 miles (1330 km) southeast of Diego Garcia.  Kenanga was moving toward the west-northwest at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 95 m.p.h. (155 km/h) and there were wind gusts to 115 m.p.h. (185 km/h).  The minimum surface pressure was 965 mb.

Tropical Cyclone Cilida Forms North of Mauritius

Tropical Cyclone Cilida formed north of Mauritius on Wednesday.  At 10:00 p.m. EST on Wednesday the center of Tropical Cyclone Cilida was located at latitude 12.2°S and longitude 59.8°E which put it about 585 miles (945 km) north-northeast of Port Louis, Mauritius.  Cilida was moving toward the southwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 55 m.p.h. (90 km/h) and there were wind gusts to 70 m.p.h. (110 km/h).  The minimum surface pressure was 989 mb.

The circulation around Tropical Cyclone Cilida organized quickly on Wednesday. A small circular eye formed at the center of circulation.  A ring of strong thunderstorms formed around the eye and the strongest winds were occurring in that ring of storms.  A strong band of storms wrapped around the western and northern sides of Cilida.  Other bands of showers and thunderstorms were revolving around the core of Tropical Cyclone Cilida.  Winds to tropical storm force extended out about 100 miles (160 km) from the center of circulation.

Tropical Storm Cilida will move through an environment favorable for intensification during the next 48 to 72 hours.  Cilida will move over water where the Sea Surface Temperature is near 27°C.  It will move through an area where the upper level winds are weak and there will be little vertical wind shear.  Cilida is likely to strengthen into the equivalent of a hurricane/typhoon on Thursday and it could intensify rapidly.  Tropical Cyclone Cilida could intensify into the equivalent of a major hurricane in two or three days.

Tropical Cyclone Cilida will move around the western end of a subtropical ridge.  The ridge will steer Cilida toward the south during the next several days.  On its anticipated track Tropical Cyclone Cilida could approach Mauritius from the north in about 48 hours.

Elsewhere over the South Indian Ocean Tropical Cyclone Kenanga drifted southeast of Diego Garcia.  At 10:00 p.m. EST on Wednesday the center Tropical Cyclone Kenanga was located at latitude 16.5°S and longitude 81.9°E which put it about 910 miles (1470 km) southeast of Diego Garcia.  Kenanga was stationary.  The maximum sustained wind speed was 125 m.p.h. (205 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 947 mb.