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Tropical Low Prompts Watch for Western Australia

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A risk posed by a Tropical Low prompted the Australian Bureau of Meteorology to issue a Watch for a portion of the coast of Western Australia on Thursday.  At 5:00 a.m. EDT on Thursday the center of the Tropical Low was located at latitude 13.8°S and longitude 121.8°E which put the center about 215 miles (350 km) west-northwest of the Kuri Bay, Australia.  The Tropical Low was moving toward the east-northeast at 5 m.p.h. (7 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 997 mb.

A Watch is in effect for the portion of the coast of Western Australia from Mitchell Plateau to Beagle Bay.  The Watch includes Derby and Beagle Bay.

A low pressure system over the South Indian Ocean west of Australia exhibited more organization on Thursday morning and the Australian Bureau of Meteorology classified the system as a Tropical Low.  The U.S. Joint Typhoon Warning Center designated the low pressure system as Invest 93S.

The distribution of thunderstorms in the Tropical Low was asymmetrical.  Thunderstorms were occurring in bands in the western side of the Tropical Low.  Bands in the eastern side of the Tropical Low consisted primarily of showers and lower clouds.  Storms near the center of circulation generated upper level divergence that pumped mass away to the west of the Tropical Low.  The removal of mass caused the surface pressure to decrease slowly.

The Tropical Low will move through an environment somewhat favorable for intensification during the next 24 hours.  The Tropical Low will move over water where where the Sea Surface Temperatures are near 29°C.  It will move under the northern part of an upper level ridge that extends from over Australia to the South Indian Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of the Tropical Low.  Those winds will cause moderate vertical wind shear.  The moderate vertical wind shear will inhibit intensification, but the wind shear may not be enough to prevent intensification.  The Tropical Low could intensify during the next 24 hours.

The Tropical Low will move around the western end of a high pressure system over northern Australia.  The high pressure system will steer the Tropical Low toward the southeast during the next 24 hours.  On its anticipated track, the Tropical Low will make landfall on the coast of Western Australia between Kuri Bay and Derby in 36 hours.

The Tropical Low will bring strong winds and locally heavy rain to parts of Western Australia.  Heavy rain could cause flash floods in some locations.

Elsewhere over the South Indian Ocean, Tropical Cyclone Courtney continued to strengthen south-southeast of the Cocos Islands.  At 5:00 a.m. EDT on Thursday the center of Tropical Cyclone Courtney was located at latitude 16.8°S and longitude 99.5°E which put the center about 380 miles (610 km) south-southeast of the Cocos Islands.  Courtney was moving toward the west at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 115 m.p.h. (185 km/h).  The minimum surface pressure was 973 mb.

Tropical Depression Brings Rain to Madagascar

A tropical depression, which is also designated as Invest 93S, brought rain to Madagascar on Saturday. At 1:00 p.m. EST on Saturday the center of the tropical depression was located at latitude 17.5°S and longitude 46.7°E which put it about 105 miles (165 km) northwest of Antananaviro, Madagascar. It was moving toward the west at 9 m.p.h. (15 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 1000 mb.

A low pressure system over northern Madagascar strengthened on Saturday and Meteo France La Reunion classified the system as tropical depression. The low pressure system was designated as Invest 93S by some other meteorological agencies. The center of the low pressure system was over Madagascar on Saturday afternoon. Bands of showers and thunderstorms were revolving around the center of the tropical depression. Storms near the center of circulation generated upper level divergence that pumped mass away to the west of the tropical depression. Some of the bands were dropping heavy rain over northern Madagascar and flash floods were possible.

The tropical depression is not likely to strengthen further during the next few hours while it is over Madagascar. The depression will move into an environment favorable for intensification on Sunday when it moves over the Mozambique Channel. The tropical depression will move over water where the Sea Surface Temperatures are near 30˚C. It will move under the northwestern part of an upper level ridge over the Southwest Indian Ocean. The ridge will produce easterly winds that will blow toward the top of the circulation. Those winds will cause some vertical wind shear, but the wind shear will not be strong enough to prevent intensification. The tropical depression could strengthen to the equivalent of a tropical storm after it moves over the Mozambique Channel.

The tropical depression will move around the northern side of a surface high pressure system over the Southwest Indian Ocean. The high pressure system will steer the tropical depression toward the west during the next 24 hours. On its anticipated track the tropical depression will move across northern Madagascar on Saturday night. The center of the depression will move over the Mozambique Channel on Sunday. The depression could approach the coast of Mozambique within 36 hours.

Tropical Cyclone Forecast to Develop, Hit Northern Madagascar

A tropical cyclone is forecast to develop over the South Indian Ocean and to hit northern Madagascar during the weekend. The system is currently a low pressure system designated as Invest 93S. At 7:00 a.m. EST on Thursday the center of Invest 93S was located at latitude 14.9°S and longitude 59.0°E which put it about 435 miles (700 km) north-northeast of Mauritius. It was moving toward the west 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. (60 km/h). The minimum surface pressure was 1006 mb.

A low pressure system, currently designated as Invest 93S, over the South Indian Ocean north-northeast of Mauritius is forecast to move west toward northern Madagascar and to develop into a tropical cyclone during the next 72 hours. The distribution of thunderstorms around the low pressure system is currently asymmetrical. The strongest thunderstorms are occurring in bands in the western side of the low pressure system. Bands in the eastern half of the circulation consist primarily of showers and lower clouds. Storms in the western half of the system generated upper level divergence that pumped mass away to the west of the low pressure system.

Invest 93S will move through an environment favorable for the development of a tropical cyclone during the next 48 hours. The low pressure system will move over water where the Sea Surface Temperatures are near 30˚C. It will move under the northwestern part of an upper level ridge over the South Indian Ocean. The ridge will produce easterly winds that will blow toward the top of the circulation. Those winds will cause moderate vertical wind shear. The wind shear is currently contributing to the asymmetrical distribution of thunderstorms. However, the vertical wind shear will not be strong enough to prevent Invest 93S from developing into a tropical cyclone.

Invest 93S will move around the northern side of a high pressure system over the South Indian Ocean. The high pressure system will steer the low pressure system toward the west-southwest during the next 48 hours. On its anticipated track Invest 93S could reach the coast of northeastern Madagascar within 72 hours. Invest 93S is forecast to be a tropical cyclone when it reaches northern Madagascar. It will bring strong winds and locally heavy rain to northern Madagascar during the weekend. Locally heavy rain could cause flash floods in some locations.