Australia Weather News

The Bureau of Meteorology has announced Tropical Cyclone Sean has officially formed as a category one system, about 150 kilometres north of Western Australia's Pilbara coast.

At 8am on Sunday, the tropical cyclone was described as having sustained winds of 85 kilometres per hour, with gusts of up to 120kph.

The system is currently moving in a west-south-westerly direction at a speed of 13kph.

At 12:30pm on Sunday, WA's Department of Fire and Emergency Services (DFES) upgraded the warning level for the coast between Mardie and Ningaloo, urging people in the area to prepare to take shelter.

DFES also issued an emergency warning for Barrow Island, 50 kilometres off the Pilbara coast, and has urged people on the island to shelter immediately.

Barrow Island is home to part of gas giant Chevron's WA operations and has cyclone-rated accommodation for workers.

Cyclone expected to stay offshore

With the track expected to remain offshore, BoM duty forecaster Caroline Crow said people in the region should expect to feel a "peripheral impact" of the system.

She said despite not feeling the full brunt of the cyclone, damaging winds were still a likelihood.

"We do have those winds extending well out from the cyclone centre," Ms Crow said.

"So it's always good to be aware of the potential impacts associated with the whole cyclone system itself, and not just looking at the cyclone’s centre."

But she said the bureau had "good confidence" the cyclone would remain offshore, following a track parallel to the Pilbara coast.

Category three system possible

However, it's expected the cyclone will continue to strengthen into a category two system, and potentially even a category three.

"By Monday morning, it could possibly be a category three cyclone," Ms Crow said.

"But it is expected to be well west of the north-west cape."

Damaging wind gusts could occur for an area between Whim Creek and Mardie, including the towns of Karratha and Dampier. 

"We've just started to see gales at Karratha airport, and those gales with damaging wind gusts are occurring about costal locations and island communities," Ms Crow said.

It's expected those conditions will move further south later on Sunday, impacting on Onslow and Exmouth. 

Destructive wind gusts could also be felt on offshore islands later on Sunday should the cyclone make a closer approach to the coast than expected.

Authorities are also expecting a storm tide for the warning area, with a possibility that large waves could produce minor flooding along the foreshore.

By Monday, the bureau expects the cyclone to turn south-west over open waters and move away from the Australian coast.

Heavy rainfall overnight

Feeling the initial brunt of the system, Port Hedland recorded 80 millimetres of rain in the 24 hours to 9am on Sunday, with a peak wind gust of 82kph.

In the same period, Exmouth recorded 26.2mm of rain, with peak gusts of 52kph.

Karratha recorded just 2.6mm of rain, but winds peaked at 83kph shortly before 9am.

Wind gusts recorded on islands off the coast demonstrate the system's power, with 107 kph recorded on Sunday morning at Legendre Island.

Ms Crow said the rainfall would likely increase and continue. 

"We will see some potentially heavy falls over Sunday and coming into Monday associated with that system," she said.

"Most of the heaviest falls will be confined to those coastal locations, potentially 50mm to 100mm possible, with some possible isolated heavy falls of up to 150mm."

People in the affected area are being urged to stay up to date via EmergencyWA and to follow community advice.