Tag Archives: SH11

Tropical Cyclone Diane Passes South of Rodrigues

Tropical Cyclone Diane passed south of Rodrigues on Saturday.  At 4:00 p.m. EST on Saturday the center of Tropical Cyclone Diane was located at latitude 22.2°S and longitude 64.7°E which put it about 190 miles (305 km) south-southeast of Port Mathurin, Maritius.  Diane was moving toward the east-southeast at 23 m.p.h. (37 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 993 mb.

Tropical Cyclone Diane brought winds to tropical storm force when it passed south of Rodrigues.  Diane also caused winds to tropical storm force over Mauritius earlier on Saturday.  A weather station at Le Morne on Mauritius measured a wind speed of 49 m.p.h. (79 km/h).  Several other weather stations on Mauritius including one at the international airport also reported winds to tropical storm force.

Tropical Cyclone Diane will move through an environment only marginally favorable for intensification.  Diane will move over water where the Sea Surface Temperature is near 27°C.  An upper level trough east of Madagascar will produce northwesterly winds which will blow toward the top of the tropical cyclone.  Those winds will cause moderate vertical wind shear which will inhibit intensification.  Tropical Cyclone Diane could strengthen a little more during the next 12 hours, but the wind shear will cause weakening in a day or two.

The upper level trough will steer Tropical Cyclone Diane toward the east-southeast during the next 24 to 36 hours.  On its anticipated track Diane will move quickly away from Rodrigues

Elsewhere over the South Indian Ocean, Tropical Cyclone Esami was churning about 1000 miles (1600 km) east of Tropical Cyclone Diane.  At 4:00 p.m. EST on Saturday the center of Tropical Cyclone Esami was located at latitude 25.9°S and longitude 74.8°E which put it about 1160 miles (1875 km) east-southeast of Port Louis, Mauritius.  Esami was moving toward the southeast at 13 m.p.h. (20 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 996 mb.

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 Dumazile Drops Heavy Rain on La Reunion

Tropical Cyclone Dumazile dropped heavy rain on La Reunion on Monday.  At 4:00 p.m. EST on Monday the center of Tropical Cyclone Dumazile was located at latitude 23.3°S and longitude 52.5°E which put it about 260 miles (420 km) southwest of St. Denis, La Reunion.  Dumazile was moving toward the south-southeast at 11 m.p.h. (17 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 949 mb.

Tropical Cyclone Dumazile strengthened into the equivalent of a major hurricane on Monday.  It was a large, powerful tropical cyclone.  There was a small circular eye at the center of the circulation.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Several rainbands were revolving around the core of the circulation.  The storms around the core were generating strong upper level divergence which was pumping mass away from the tropical cyclone.  Winds to hurricane/typhoon force extended out about 90 miles (145 km) from the center of circulation.  Winds to tropical storm force extended out about 250 miles (400 km) from the center.

The Hurricane Intensity Index (HII) for Tropical Cyclone Dumazile was 20.6.  The Hurricane Size Index (HSI) was 30.3 and the Hurricane Wind Intensity Size Index (HWISI) was 50.9.  Those indices indicate that Tropical Cyclone Dumazile would be capable of causing extensive major damage if it made landfall.

Although the core of Tropical Cyclone Dumazile passed between Madagascar and La Reunion, the circulation was so large that rainbands on the eastern side of Dumazile passed over La Reunion.  Those rainbands dropped locally heavy rain and there were unconfirmed reports of flooding in parts of La Reunion.

Tropical Cyclone Dumazile has likely reached its peak intensity.  Dumazile is currently moving over water where the Sea Surface Temperature is near 28°C, but the tropical cyclone will move over colder water when it moves farther south.  An upper level trough near southern Africa is producing northwesterly winds which are blowing toward the top of the circulation.  Those winds are generating vertical wind shear and the shear is forecast to increase during the next several days.  The colder water and increased wind shear are forecast to weaken Tropical Cyclone Dumazile during the next few days.

Tropical Cyclone Dumazile has rounded the western end of a subtropical ridge and it is now moving toward the south-southeast.  A general southeastward motion is forecast for the next two or three days.  On its anticipated track Tropical Cyclone Dumazile should move away from Madagascar and La Reunion.

Tropical Cyclone Dumazile Passes Between Madagascar and La Reunion

Tropical Cyclone Dumazile passed between Madagascar and La Reunion on Sunday night.  At 10:00 p.m. EST on Sunday the center of Tropical Cyclone Dumazile was located at latitude 20.7°S and longitude 51.1°E which put it about 280 miles (450 km) west of St. Denis, La Reunion.  Dumazile was moving toward the south-southeast at 11 m.p.h. (17 km/h).  The maximum sustained wind speed was 105 m.p.h. (170 km/h) and there were wind gusts to 125 m.p.h. (205 km/h).  The minimum surface pressure was 961 mb.

Dumazile is a very well organized tropical cyclone. The circulation is symmetrical and there is a small circular eye at the center of circulation.  The eye is surrounded by a ring of strong thunderstorms and the strongest winds are occurring in that ring.  Bands of showers and thunderstorms are revolving around the core of the circulation.  Storms in the core are generating strong upper level divergence which is pumping mass away from the tropical cyclone.  Winds to hurricane/typhoon force extended out about 70 miles (110 km) from the center of circulation.  Winds to tropical storm force extended out about 230 miles (370 km) from the center.

Tropical Cyclone Dumazile will move through an environment favorable for intensification for about another 24 hours.  Dumazile will move over water where the Sea Surface Temperature is near 29°C.  It will move under an area where the upper level winds are weak and there will be little vertical wind shear.  Tropical Cyclone Dumazile could strengthen into the equivalent of a major hurricane on Monday.  When Dumazile moves farther south in a day or so, it will move over cooler water and into an area where the upper level winds are stronger.  Cooler water and more vertical wind shear will cause Tropical Cyclone Dumazile to weaken when that happens.

Tropical Cyclone Dumazile has rounded the western end of a subtropical ridge and it is now moving toward the south-southeast.  A general southeasterly motion is expected during the next few days.  On its anticipated track Tropical Cyclone Dumazile will move away from Madagascar.  Dumazile is forecast to pass southwest of La Reunion.

Tropical Cyclone Dumazile Brings Wind and Rain to Eastern Madagascar

Tropical Cyclone Dumazile brought wind and rain to eastern Madagascar on Saturday.  At 10:00 p.m. EST on Saturday the center of Tropical Cyclone Dumazile was located at latitude 17.0°S and longitude 51.5°E which put it about 90 miles (145 km) east of Ambodifotatra, Madagascar.  Dumazile was moving toward the southwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 979 mb.

Tropical Cyclone Dumazile intensified rapidly into the equivalent of a hurricane/typhoon on Saturday.  Satellite images suggested that an eye was forming at the center of circulation.  The developing eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in the ring of storms.  Additional bands of showers and thunderstorms were revolving around the core of the circulation.  Storms in the core were generating strong upper level divergence which was pumping large quantities of mass away from the tropical cyclone.  Winds to hurricane/typhoon force extended out about 45 miles (75 km) from the center of circulation.  Winds to tropical storm force extended out about 200 miles (320 km) from the center.

Tropical Cyclone Dumazile will move through an environment very favorable for intensification during the next 24 hours.  Dumazile will move over water where the Sea Surface Temperature is near 30°C.  It will continue to move through a region where the upper level winds are weak and there is little vertical wind shear.  Tropical Cyclone Dumazile is likely to continue to intensify rapidly on Sunday and it could strengthen into the equivalent of a major hurricane.

Tropical Cyclone Dumazile is moving around the western end of a subtropical high pressure system which is steering the tropical cyclone toward the southwest.  Dumazile is likely to move more toward the south as it moves around the western end of the ridge.  On its anticipated track the core of Tropical Cyclone Dumazile is forecast to pass east of the coast of Madagascar.  However, rainbands on the western side of the circulation will bring gusty winds and locally heavy rain to parts of eastern Madagascar.  Heavy rain could cause flash floods in some locations.

Tropical Cyclone 11S Forms East of Northern Madagascar

Tropical Cyclone 11S formed east of the northern tip of Madagascar on Friday.  At 4:00 p.m. EST on Friday the center of Tropical Cyclone 11S was located at latitude 13.2°S and longitude 54.3°E which put it about 535 miles (865 km) north of St. Denis, La Reunion.  It was moving toward the southeast at 4 m.p.h. (6 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 996 mb.

A distinct center of circulation finally developed on Friday in an area of thunderstorms that had been stationary northeast of Madagascar.  A primary band of storms wrapped around the northern side of the center of circulation and then storms began to develop near the center.  Additional bands of showers and thunderstorms were revolving around the core of the circulation and the structure of the circulation was organized enough to be classified as a tropical cyclone.  Storms near the center of circulation began to generate upper level divergence which was pumping mass away from the tropical cyclone.

Tropical Cyclone 11S will be moving through an environment that is very favorable for intensification.  It will move over water where the Sea Surface Temperature is near 30°C.  Tropical Cyclone 11S is located under an upper level ridge and the upper level winds are weak.  There is little vertical wind shear to inhibit intensification.  Tropical Cyclone 11S will intensify during the weekend and it is likely to intensify rapidly at times.  Tropical Cyclone 11S could strengthen into the equivalent of a major hurricane during the next two or three days.

Tropical Cyclone 11S and its precursor have been in an area where the steering winds were weak.  A subtropical ridge located to the east of the tropical cyclone is forecast to strengthen.  The ridge will steer Tropical Cyclone 11S toward the south-southwest.  Early model guidance suggests that the center of the tropical cyclone will move between Madagascar and La Reunion, but there is still uncertainty in the future track of the system.

Tropical Cyclone Winston Stalls Between Vanuatu and Fiji

Steering currents weakened on Sunday and Tropical Cyclone Winston stalled about half way between Vanuatu and Fiji.  At 10:00 p.m. EST on Sunday the center of Tropical Cyclone Winston was located at latitude 18.0°S and longitude 172.5°E which put it about 300 miles (480 km) east of Port Vila, Vanuatu.  Winston was moving toward the west-southwest at 3 m.p.h. (5 km/h).  The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 135 m.p.h. (215 km/h).  The minimum surface pressure was 952 mb.

Vertical wind shear over Winston decreased on Sunday and the organization of the tropical cyclone improved.  The eye has become more visible on satellite images and thunderstorms surrounding the eye are generating more upper level divergence.  Easterly winds which were blowing over the top of Winston diminished and the upper level divergence is again flowing out in all directions.

Tropical Cyclone Winston is in an environment that favors intensification.  It is over water where the Sea Surface Temperature is near 30°C.  There is not much vertical wind shear and Winston is likely to intensify during the next 24 hours.

Winston has moved into an area that is between two subtropical ridges.  As a result, it is in an area where the steering winds are not very strong.  The forward motion of Winston has slowed and there is some indication that it may be turning southward.  The guidance from numerical models is forecasting a southerly or southeasterly motion during the next 24 to 48 hours.  On its anticipated track Tropical Cyclone Winston is predicted to stay east of Vanuatu.  However, a more westerly track could bring it closer to that country.

Tropical Cyclone Winston Hits Viti Levu Then Moves West of Fiji

The eye of destructive Tropical Cyclone Winston moved over the northern part of Viti Levu and then continued west of Fiji.  At 10:00 p.m. EST on Saturday the center of Tropical Cyclone Winston was located at latitude 17.5°S and longitude 174.4°E which put it about 425 miles (685 km) east of Port Vila, Vanuatu.  Winston was moving toward the west at 13 m.p.h. (21 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 937 mb.  Winston was the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.

The core of intense Tropical Cyclone Winston was disrupted as it moved across the northern portion of Viti Levu.  However, the core reorganized once it moved back over water.  It has a well formed eye surrounded by a circular eyewall.  Several rainbands are spiraling around the core.  Thunderstorms in the core of Tropical Cyclone Winston are generating upper level divergence.

The environment surrounding Tropical Cyclone Winston is a little less favorable for intensification.  Winston is still moving over water where the Sea Surface Temperature is near 30°C.  However, an upper level ridge located to the southeast of Winston is generating easterly winds that are inhibiting upper level divergence to the east of the tropical cyclone.  There is still strong upper level divergence in the western half of the circulation.  The vertical wind shear has caused Winston to weaken slowly, but the shear has not been strong enough to disrupt the reorganization of the circulation.  Tropical Cyclone Winston could maintain its intensity or even strengthen somewhat during the next day or two.

The subtropical ridge southeast of Winston is steering the tropical cyclone toward the west and that general motion is expected to continue for at least another 24 hours.  Guidance from numerical models suggest that Winston will turn toward the south early next week.  However, the guidance from the models has consistently forecast a turn to the south that has not yet occurred.  The guidance predicts that Tropical Cyclone Winston will turn south before it can affect Vanuatu, but people in that country should monitor the progress of Winston closely.

Radar and satellite information indicate that the northern eyewall of Tropical Cyclone Winston may have moved over the southern part of Vanua Levu.  The eye moved across the northern part of Viti Levu.  Press reports indicated Winston produced significant wind damage and power outages in parts of Fiji.