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Tropical Cyclone Wallace Churns Northwest of Australia

Tropical Cyclone Wallace continued to churn northwest of Australia on Sunday.  At 11:00 p.m. EDT on Sunday the center of Tropical Cyclone Wallace was located at latitude 15.3°S and longitude 116.4°E which put it about 435 miles (700 km) north of Karratha, Australia.  Wallace was moving toward the southwest at 11 m.p.h. (17 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 987 mb.

The circulation around Tropical Cyclone Wallace exhibited signs of greater organization on Sunday.  The inner end of a band of showers and thunderstorms wrapped around the southern and western sides of the center of circulation.  More thunderstorms formed in other bands that were revolving around the core of Tropical Cyclone Wallace.  Storms near the core were generating upper level divergence which was pumping mass away to the west and south of the tropical cyclone.  Winds to tropical storm force extended out about 140 miles (220 km) from the center of circulation.

Tropical Cyclone Wallace will move through an environment somewhat favorable for intensification during the next 24 hours.  Wallace will move over water where Sea Surface Temperature is near 28°C.  It will move near the western end of an upper level ridge over northern Australia.  The ridge will produce easterly winds which will cause moderate vertical wind shear.  The shear will limit intensification, but it may not be great enough to prevent Tropical Cyclone Wallace from getting stronger.  Wallace could strengthen into the equivalent of a hurricane/typhoon during the next 24 hours.

The ridge over northern Australia will steer Tropical Cyclone Wallace toward the west-southwest during the next few days.  On its anticipated track Wallace is forecast to remain north of Western Australia.

Tropical Cyclone Wallace Develops North of Western Australia

Tropical Cyclone Wallace developed over the Timor Sea north of Western Australia on Friday.  At 2:00 p.m. EDT on Friday the center of Tropical Cyclone Wallace was located at latitude 11.7°S and longitude 125.7°E which put it about 280 miles (440 km) north-northeast of Kuri Bay, Australia.  Wallace was moving toward the west at 6 m.p.h. (9 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.

The Australian Bureau of Meteorology posted a Tropical Cyclone Warning from Kalumburu to Beagle Bay.

More thunderstorms developed near the center of a Tropical Low over the Timor Sea on Friday and the Australian Bureau of Meteorology designated the system as Tropical Cyclone Wallace.  The distribution of thunderstorms in the circulation around Wallace was asymmetrical.  Most of the thunderstorms were occurring west of the center of circulation and in bands in the western half of the tropical cyclone.  Bands in the eastern half of of Tropical Cyclone Wallace consisted primarily of showers and lower clouds.  Winds to tropical storm force extended out about 150 miles (240 km) from the center of circulation.

Tropical Cyclone Wallace was moving north of an upper level ridge.  The ridge was producing strong easterly winds which were causing significant vertical wind shear.  Those winds and the shear were probably the cause of the asymmetrical distribution of thunderstorms.  Storms west of the center of circulation were generating upper level divergence which was pumping mass away to the west of Tropical Cyclone Wallace.

Tropical Cyclone Wallace may move into an area more favorable for intensification during the next day or two.  Wallace could move into an area where the upper level winds are not quite as strong.  Tropical Cyclone Wallace will move over water where the Sea Surface Temperature is near 29°C.  So, if it moves into an area where the shear is less, then Tropical Cyclone Wallace is likely to strengthen.  There is a chance Wallace could intensify into the equivalent of a hurricane/typhoon during the next two or three days.

Tropical Cyclone Wallace will move around the northwestern end of a subtropical ridge over Australia.  The ridge will steer Wallace toward the west-southwest during the next several days.  On its anticipated track the core of Tropical Cyclone Wallace is forecast to stay north of the coast of Western Australia during the next few days.

Tropical Cyclone Veronica Stalls, Weakens Near Western Australia Coast

Tropical Cyclone Veronica stalled and weakened near the coast of Western Australia west of Port Hedand.  At 5:00 p.m. EDT on Sunday the center of Tropical Cyclone Veronica was located at latitude 20.5°S and longitude 117.5°E which put it about 70 miles (110 km) west of Port Hedland.  Veronica was moving toward the southwest at 2 m.p.h. (3 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 974 mb.  A Tropical Cyclone Warning remained in effect from Port Hedland to Mardie including Karratha and Barrow Island.

The southern eyewall of Tropical Cyclone Veronica moved over the coast of Western Australia west of Port Hedland on Saturday night.  Veronica was the equivalent of a major hurricane and there would have been a period of strong winds near the coast.  It likely caused some wind damage and generated a storm surge at the coast.  An upper level trough west of Australia produced strong northwesterly winds that reached the top of Tropical Cyclone Veronica as it neared the coast.  Those winds produced very strong vertical wind shear and they blew the upper half of the circulation southeast of the lower half of the tropical cyclone.  The decoupling of the upper and lower parts of the circulation caused Tropical Cyclone Veronica to weaken very quickly during the past 12 hours.  Veronica weakened from the equivalent of a major hurricane to a tropical storm.

The strong wind shear also generated an asymmetrical distribution of rainfall.  Most of the rain was falling in the southeastern half of the circulation which was over Western Australia.  Bands in the northwestern half of the circulation consisted primarily of showers and lower clouds.  Locally heavy rain could produce flooding in a few locations, but the rapid weakening of Tropical Cyclone Veronica will reduce the risk of flooding.

Tropical Cyclone Veronica will continue to weaken quickly because of the strong vertical wind shear.  The decoupling of the upper and lower halves of the circulation has resulted in little motion during the past few hours.  However, the lower half of Veronica will be steered more by the winds in the lower troposphere.  Those winds will steer Tropical Cyclone Veronica toward the west-southwest during the next day or two.  On its anticipated track the lower half of Veronica will move near the coast of Western Australia.  On its anticipated track Tropical Cyclone Veronica will pass near Wickham, Karratha, Dampier, Onslow and Exmouth.  Veronica will bring some gusty winds, but it should pose a limited risk.

Elsewhere over the South Indian Ocean, Tropical Cyclone Joaninha was strengthening northwest of Rodrigues.  At 5:00 p.m. EDT on Sunday the center of Tropical Cyclone Joaninha was located at latitude 17.4°S and longitude 62.0°E which put it about 180 miles (290 km) northwest of Rodrigues, Mauritius.  Joaninha was moving toward the southeast at 2 m.p.h. (3 km/h).  The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 130 m.p.h. (210 km/h).  The minimum surface pressure was 956 mb.