The potential risk posed by a Tropical Low prompted the Australia Bureau of Meteorology to issue a Warning for a portion of the coast of Western Australia on Thursday. At 10:00 p.m. EST on Thursday the center of a Tropical Low was located at latitude 17.9°S and longitude 121.5°E which put the center about 25 miles (40 km) west-northwest of Broome, Australia. The Tropical Low was moving toward the west at 8 m.p.h. (13 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.
The Australian Bureau of Meteorology issued a Warning for the portion of the coast of Western Australia from Pardoo Roadhouse to Whim Creek. The Warning included Port Hedland.
The Australian Bureau of Meteorology issued a Watch for the portion of the coast of Western Australia from Whim Creek to Exmouth Gulf. The Watch included Karratha,Dampier, and Onslow.
A low pressure system strengthened on Thursday when it moved over the South Indian Ocean near Broome, Australia. The Australian Bureau of Meteorology designated the system as a Tropical Low. The U.S. Joint Typhoon Warning Center designated the system as Tropical Cyclone 20S.
The Tropical Low started to strengthen on Thursday as soon as it moved over the water in the South Indian Ocean. More thunderstorms formed near the center of the Tropical Low. Thunderstorms also developed in bands revolving around the center of circulation. Storms near the center began to generate upper level divergence that pumped mass away from the Tropical Low. The removal of mass caused the surface pressure to start to decrease.
The Tropical Low will move through an environment very favorable for intensification during the next 24 hours. The Tropical Low will then move over water where the Sea Surface Temperatures are near 29°C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. The Tropical Low will intensify during the next 24 hours. It could intensify rapidly to the equivalent of a hurricane/typhoon.
The Tropical Low will move around the northwestern part of a high pressure system that is over Australia. The high pressure system will steer the Tropical Low toward the west-southwest during the next 24 hours. On its anticipated track, the Tropical Low will be north of Port Hedland in 24 hours.
The center of the Tropical Low is likely to stay north of the coast of Western Australia on Friday. Bands in the southern half of the Tropical Low could bring gusty winds and locally heavy rain to portions of the coast.