Tag Archives: Invest 92S

Tropical Low Forms North of Australia

A Tropical Low formed north of Australia late on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of the Tropical Low as located at latitude 9.2°S and longitude 130.9°E which put it about 155 miles (250 km) north of Milikapiti, Australia.  It was moving toward the east at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 30 m.p.h. (45 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1004 mb.  The Australian Bureau of Meteorology issued a Watch for the portion of the coast from Milingimbi to Daly River Mouth including Darwin and the Tiwi Islands.

A center of circulation developed in an area of showers and thunderstorms north of Australia late on Wednesday and the Australian Bureau of Meteorology classified the system as a Tropical Low.  The circulation was still organizing.  A short band of showers and thunderstorms wrapped around the southern and western sides of the center.  Other short rainbands were developing in other parts of the circulation.  Storms near the center of circulation were just beginning to generate upper level divergence.

The Tropical Low will move through an environment somewhat favorable for intensification.  It will mover over water where the Sea Surface Temperature is near 30°C.  Westerly winds in the upper levels will cause some vertical wind shear, which will inhibit intensification.  However, the shear is not likely to be strong enough to prevent intensification.  The Tropical Low is likely to strengthen during the next 24 hours.  After that time the intensity will be influenced by how much of the circulation is over Australia.

The Tropical Low is being steered to the east by westerly winds north of Australia.  Those winds are forecast to weaken and the Tropical Low is expected to turn south toward the coast of Australia.  A subtropical ridge over Australia is expected to turn the Tropical Low toward the southwest in a day or so.  On its anticipated track the Tropical Low could be near the northern coast of Australia in 24 to 36 hours.  It could pass near the Cobourg Peninsula, Melville Island and Bathurst Island.  The Tropical Low could also bring gusty winds and heavy rain to the area near Darwin.

Tropical Low Develops Near Coast of Western Australia

A distinct low level center of circulation developed in an area of thunderstorms near the coast of Western Australia on Tuesday and the Australian Bureau of Meteorology classified the system as a Tropical Low.  At 10:00 p.m. EST on Tuesday the center of the Tropical Low as located at latitude 17.2°N and 122.3°E which put it just inland east of Coulomb Point and about 55 miles (85 km) north of Broome, Australia.  The Tropical Low was moving toward the southwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 998 mb.

Although the center of circulation was over land, the circulation of the Tropical Low became much better organized on Tuesday.  There was a well defined center of circulation and weather radar images indicated an eyelike feature at the center of the Tropical Low.  Several bands of showers and thunderstorms wrapped around the center of circulation.  Storms in the core of the Tropical Low were generating well developed upper level divergence which was pumping mass away in all directions.

The Tropical Low will move through an environment favorable for intensification during the next 24 to 36 hours.  The Sea Surface Temperature of the water off the coast of Western Australia is near 30°C.  The Tropical Low is underneath an upper level ridge and the upper level winds are not very strong.  There is little vertical wind shear.  The only factor inhibiting intensification is the fact that the center is still inland over Western Australia.  If the center moves over water as is forecast, the Tropical Low will intensify and it could intensify rapidly.

The Tropical Low is moving around the western end of a mid-level ridge which is steering it toward the southwest.  The ridge is forecast to steer the Tropical Low toward the southwest for another 12 to 24 hours.  When the Tropical Low reaches the western end of the ridge, it will move more toward the south.  On its anticipated track the center of the Tropical Low will move off the coast of Western Australia and over water during the next 6 to 12 hours.  The center of the Tropical Low is expected to pass west of Broome.  The Tropical Low could approach the coast of Western Australia between Bidyadanga and Wallal Downs in about 36 hours.

The Tropical Low will drop heavy rain along the coast of Western Australia during the next 48 hours.  It will also bring gusty winds and a Warning has been issued for the portion of the coast from Cape Leveque to De Grey.

Tropical Cyclone Organizing Over Southwest Indian Ocean

A tropical cyclone organized north of La Reunion and east of Madagascar over the Southwest Indian Ocean on Friday.  At 1:00 p.m. EST on Friday the center of the tropical cyclone was located at latitude 14.5°N and longitude 56.1°E, which put it about 435 miles (700 km) north of La Reunion.  The tropical cyclone was moving toward the south at 5 m.p.h. (8 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.

An area of showers and thunderstorms persisted north of La Reunion for much of the past week.  Curved bands of showers and thunderstorms began to develop on Friday and the circulation took on more of a circular shape.  Thunderstorms near the center of the circulation began to generate upper level divergence which was pumping out mass and the surface pressure started to decrease.  There is a distinct center in the low level circulation and the tropical cyclone would be the equivalent of a tropical depression if it were over the Atlantic or Pacific Oceans.

The environment surrounding the tropical cyclone is favorable for further intensification.  The tropical cyclone is over water where the Sea Surface temperature is around 28.5°C.  So, there is plenty of energy in the upper ocean.  The upper level winds over the tropical cyclone are light and there is little vertical wind shear.  The absence of vertical wind shear is allowing the upper level divergence to pump out mass in all directions.  The tropical cyclone is expected to strengthen during the next 24 hours and it could intensify quickly if the inner core continues to develop.

The winds at the steering level are weak, which is why the system did not move much during the past few days.  Weak northerly winds could push the tropical cyclone slowly toward the south toward Mauritius and La Reunion.  The tropical cyclone could be near those islands in about three or four days.