The Bureau of Meteorology has issued a storm advice for the South West of WA including Mandurah and Bunbury.
A slow-moving cold front is producing "persistent rain with embedded thunderstorms".
Affected locations include Bunbury, Busselton, Mandurah, Collie, Harvey and Dwellingup.
Heavy rainfall may lead to flash flooding with six-hourly rainfall totals between 30mm and 60mm expected.
Bunbury has already recorded more than 40mm of rain.
Conditions are expected to ease later this evening.
The Department of Fire and Emergency Services advises that people should:
* If outside find safe shelter away from trees, power lines, storm water drains and streams.
* Close your curtains and blinds, and stay inside away from windows.
* Unplug electrical appliances and do not use land line telephones if there is lightning.
* If boating, swimming or surfing leave the water.
* Be alert and watch for hazards on the road such as fallen power lines and loose debris.
* Keep away from flooded drains, rivers, streams and waterways.
* Be careful of fallen trees, damaged buildings and debris.
* Be careful of fallen power lines. They are dangerous and should always be treated as live.
* Assess your home, car and property for damage.
* If damage has occurred take photos and contact your insurance company to organise permanent repairs.
* If your home or property has significant damage, like a badly damaged roof or flooding, call the SES on 132 500.
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