Tag Archives: Western Australia

Tropical Cyclone Quang Intensified Rapidly Into Equivalent of a Major Hurricane

Tropical Cyclone Quang intensified very rapidly on Wednesday and it reached an intensity equivalent to a major hurricane.  At 10:00 p.m. EDT on Wednesday the center of Tropical Cyclone Quang was located at latitude 17.0°S and longitude 109.2°E which put it about 460 miles northwest of Exmouth and about 610 miles north-northwest of Carnarvon, Australia.  Quang was moving south-southeast at 6 m.p.h.  The maximum sustained wind speed was 130 m.p.h. and there were gusts to 160 m.p.h.  The minimum surface pressure was 940 mb.

As Quang moved across very warm Sea Surface Temperatures (SSTs), the upper level winds eased enough to allow it to intensify very rapidly.  Thunderstorms around the eyewall transported mass upward and generated upper level divergence in all directions, which allowed the surface pressure to decrease quickly.  The decrease in surface pressure generated the rapid increase in wind speed.    Quang is a small tropical cyclone and small tropical cyclones can intensify and weaken more quickly than larger storms.  Quang may have peaked in intensity.  As it moves farther south it will move over cooler SSTs.  Upper level wind speeds will increase along the projected track creating more vertical wind shear.  In addition, it appears that some drier air may be entering the northwestern part of the circulation.  The combination of cooler SSTs, more wind shear and drier air is likely to weaken Quang significantly before it reaches the coast of Western Australia.

Quang is moving around the western end of a subtropical ridge.  As it moves toward higher latitudes, westerly winds are likely to steer it more toward the southeast.  Quang could be approaching the coast of Western Australia between Onslow and Denham in about 48 to 60 hours.

 

Tropical Cyclone Quang Forms Northwest of Australia

After several quiet weeks in the tropics a low level circulation developed in an area of thunderstorms northwest of Australia and the system was classified as Tropical Cyclone Quang (24S) on Tuesday.  At 10:00 p.m. EDT on Tuesday the center of Tropical Cyclone Quang was located at latitude 15.2°S and longitude 109.7°E which put it about 550 miles northwest of Exmouth, Australia.  Quang was moving toward the southwest at 6 m.p.h.  The maximum sustained wind speed was 45 m.p.h. and there were gusts to 65 m.p.h.  The minimum surface pressure was 997 mb.

Tropical Cyclone Quang developed over an area where the Sea Surface Temperatures (SSTs) are near 30°C.  A subtropical ridge to the east of Quang is generating some northeasterly winds over the circulation in the upper levels.  The resulting vertical wind shear is slowing the intensification of the circulation.  However, satellite imagery indicates that Quang is becoming more well organized.  A primary rainband has wrapped most of the way around the center of circulation and an eye may be forming.  Thunderstorms near the center of circulation are increasing the upper level outflow, especially on the southern side of Quang.  Further intensification is likely and Quang could reach hurricane intensity in 24 to 48 hours.  Eventually, when Quang moves farther south, it will move over cooler SSTs.  Vertical wind shear is also likely to increase at the same time, and Quang is likely to weaken as it approaches Western Australia.

Tropical Cyclone Quang is moving around the western end of the subtropical ridge.  As it reaches the western end of the ridge, it is likely to take a more southerly track on Wednesday.  By Thursday westerly winds are forecast to begin to steer Quang to the southeast.  On its projected track, Quang would approach the coast of Western Australia in about three days.  If it weakens as expected, Quang would bring some wind and rain when it moves across Western Australia.

Tropical Cyclone Nathan Weakening Over Northern Australia

The center of Tropical Cyclone Nathan moved inland between Maningrida and Goulburn Island on the northern coast of Australia on Monday.  At 11:00 p.m. EDT on Monday the center of Tropical Cyclone Nathan was located at latitude 12.2°S and longitude 133.5°E which put it about 30 miles east-northeast of Gunbalanya, about 45 miles south of Goulburn Island and about 210 miles east of Darwin, Australia.  Nathan was moving toward the southwest at 8 m.p.h.  The maximum sustained wind speed was 45 m.p.h. and there were gusts to 60 m.p.h.  The minimum surface pressure was 989 mb.

A combination of factors contributed to the weakening of Nathan.  As the center of circulation moved inland, the clockwise flow pulled in drier air from the interior of Australia.  The drier air reduced the number of thunderstorms and decreased the amount of latent energy released in the remaining thunderstorms.  Since the release of latent energy drives the circulation in a tropical cyclone, the wind speed has been decreasing as well.  In addition, northerly winds in the upper levels are creating moderate vertical wind shear over the top of Nathan.  The wind shear is displacing many of the remaining thunderstorms to the south side of the circulation.  The asymmetrical development of thunderstorms has weakened the inner core of the circulation.  As long as the center of circulation remains over land, it is likely to weaken further.

A subtropical ridge to the south of Nathan is expected to steer it in a mainly westerly direction.  The projected track would take the center of Nathan south of Darwin and keep it over land for about another 36 hours.  The circulation could be fairly weak by the time it moves back over water west of Darwin.  The water west of Darwin is warm and so, it is possible that more thunderstorms could develop, if there is a coherent circulation when the system moves back over the water.