Tropical Cyclone Ilsa rapidly intensified to the equivalent of a hurricane/typhoon on Tuesday. At 5:00 p.m. EDT on Tuesday the center of Tropical Cyclone Ilsa was located at latitude 15.9°S and longitude 120.3°E which put it about 190 miles (305 km) northwest of Broome, Australia. Ilsa was moving toward the southwest at 9 m.p.h. (15 km/h). The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (150 km/h). The minimum surface pressure was 975 mb.

A Tropical Cyclone Watch was in effect for the portion of the coast of Western Australia from Beagle Bay to Whim Creek. The Tropical Cyclone Watch included Broome and Port Hedland.

Tropical Cyclone Ilsa intensified rapidly over the South Indian Ocean northwest of Australia on Tuesday. The inner end of a rainband wrapped around the center of Ilsa’s circulation. Other bands of showers and thunderstorms were revolving around the center of circulation. Storms near the center generated strong upper level divergence that pumped a large quantity of mass away from the tropical cyclone. The removal of a large quantity of mass caused the surface pressure to decrease rapidly, which contributed to the rapid increase in wind speed.

The circulation around Tropical Cyclone Ilsa was small. Winds to hurricane/typhoon force extended out 30 miles (50 km) from the center of Ilsa’s circulation. Winds to tropical storm force extended out 75 miles (120 km) from the center of circulation.

Tropical Cyclone Ilsa will move through an environment very favorable for intensification during the next 24 hours. Ilsa will move over water where the Sea Surface Temperatures are near 30˚C. It will move under the axis of an upper level ridge that extends from northern Australia to the South Indian Ocean. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. Tropical Cyclone Ilsa is likely to continue to intensify rapidly during the next 24 hours. Ilsa could intensify to the equivalent of a major hurricane within 24 hours.

Tropical Cyclone Ilsa will move around the northwestern part of a high pressure system over western Australia. The high pressure system will steer Ilsa toward the southwest during the next 18 hours. Tropical Cyclone Ilsa will move toward the south when it reaches the western end of the ridge on Wednesday. On its anticipated track, Ilsa is likely to make landfall on the coast of Western Australia between Broome and Port Hedland in 48 hours. The center of Tropical Cyclone Ilsa could make landfall near Wallal Downs. Ilsa is likely to be the equivalent of a major hurricane when it makes landfall.