Tropical Cyclone Sean rapidly intensified to the equivalent of a major hurricane over the South Indian Ocean west of Australia on Monday. At 10:00 a.m. EST on Monday the center of Tropical Cyclone Sean was located at latitude 23.0°S and longitude 110.4°E which put the center about 210 miles (340 km) west of Exmouth, Australia. Sean was moving toward the southwest at 13 m.p.h. (21 km/h). The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 160 m.p.h. (260 km/h). The minimum surface pressure was 936 mb.
A Warning was in effect for the portion of the coast from Onslow to Ningaloo. The Warning included Exmouth.
Tropical Cyclone Sean rapidly intensified to the equivalent of a major hurricane west of Australia on Monday. A small circular eye with a diameter of 10 miles (16 km) was at the center of Sean’s circulation. The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Tropical Cyclone Sean. Storms near the core of Sean generated strong upper level divergence that pumped large quantities of mass away from the tropical cyclone. The removal of large amounts of mass caused the surface pressure to decrease rapidly.
The circulation around Tropical Cyclone Sean was relatively small. Winds to hurricane/typhoon force extended out 35 miles (55 km) from the center of Sean’s circulation. Winds to tropical storm force extended out 110 miles (175 km) from the center of Tropical Cyclone Sean.
The Hurricane Intensity Index (HII) for Tropical Cyclone Sean was 25.1. The Hurricane Size Index (HSI) was 12.6 and the Hurricane Wind Intensity Size Index (HWISI) was 37.7. Tropical Cyclone Sean was similar in size and intensity to Hurricane Harvey when Harvey hit Texas in 2017.
Tropical Cyclone Sean will move through an environment that will become unfavorable for intensification during the next 24 hours. Sean will move over water where where the Sea Surface Temperatures are near 27°C. It will move under the eastern part of an upper level trough over the South Indian Ocean. The upper level trough will produce northwesterly winds are that will blow toward the top of Sean’s circulation. Those winds will cause the vertical wind shear to increase. The combination of cooler water and more vertical wind shear will cause Tropical Cyclone Sean to weaken during the next 24 hours.
Tropical Cyclone Sean will move around the northwestern part of a high pressure system over Australia. The high pressure system will steer Sean toward the southwest during the next 24 hours. On its anticipated track, Tropical Cyclone Sean will move a little farther away from the coast of Western Australia.
Bands in the eastern side of Tropical Cyclone Sea will bring gusty winds and locally heavy rain to the coast of Western Australia. Heavy rain could cause floods in some locations. 10.78 inches (274 mm) of rain has already fallen at the Karratha Airport. 4.37 inches (111 mm) of rain has already fallen at the Mardie Airport.
Flood Warnings were in effect for parts of the Pilbara and northern Gascoyne regions. A Flood Warning was in effect for the Lyndon-Minilya Rivers.