UPDATE 3pm: Collie is suffering from widespread flooding as unseasonal weather continues to batter Western Australia’s south.
The Bureau of Meteorology’s Neil Bennett said more than 100mm of rainfall had already been recorded at Harvey. Myalup has seen 90mm, with Collie recording 43mm in just two hours.
Mandurah has had its wettest December day on record, while heavy rainfall at Harvey has been described as a one-in-100-year event.
Thousands of homes remain without power across the State, the worst affected areas are Shoalwater, Rockingham, Safety Bay and Cannington.
The Collie River is currently below the minor flood level and rising. Major flooding is expected to
develop around and downstream of Collie early Thursday morning.
DFES’s State Emergency Service advises people and communities to be aware that flooding is possible and be prepared to relocate equipment and livestock.
Collie Visitors Centre consultant Tania Roberts said the rain had been continuous in the area since about 10.30am. She said some streets had been blocked off due to flooding.
“The rain is really heavy and there has been loud thunder and lightning continuously,” she said.
“It’s steady at the moment but then it comes in heavy and really buckets down.
"The visitor centre has actually flooded in one corner. The rain has come through the windows and down the walls, through the eves and everything so we have been mopping up all day.”
Collie East has recorded 92.6mm of rain since 9am and Yourdamung Lake in the Collie region received 170mm.
A Collie Police spokeswoman said rain was starting to ease up but quite a bit of storm damage had already been reported.
“The whole town is affected at the moment,” she said.
Flood Warnings have been issued for the Collie and Murray rivers
Thunderstorms are forecast to continue on Wednesday and into Thursday, prompting the Department of Fire and Emergency Services to warn of possible minor flooding in the shires of Harvey, Murray and Waroona.
“There are already signs of rapid river rises in the Harvey area,” Mr Bennett said.
Mandurah experienced its second wettest day in 11 years yesterday, with 70.2mm of rain falling mainly between 10pm and midnight. This was a one-in-50-year event, Mr Bennett said.
The storms have also led to minor flooding across some parts of Perth, while Rockingham Hospital to the city’s south has sustained flood damage.
Rockingham was the worst hit by storms overnight, with the DFES receiving 90 calls for help.
“DFES is now putting in place preparations for a second front that will cross the coast this afternoon,” it said.
A Western Power spokeswoman told ABC radio about half of the 4000 homes across the state without power this morning were in Mandurah and Rockingham.
“Crews are working to restore the damage and hopefully it won’t be too long,” she said.
“These are pretty small numbers compared to last week. We had about 50,000 without power, so 4000 is not particularly bad and most of that was due to lightning strikes.”
Rockingham resident Kiyah Best said the storm was the worst she had seen in the five years she has lived in the area.
She said her partner went outside to help two motorists who were stuck in knee deep water near her Cambridge Crescent home about 10.30pm.
"To start with it was sort of like light rain and then it came down pretty heavy," she said.
"Our gutters couldn't cope and water was spilling out of them.
"The water was ankle deep in the backyard. It was pretty intense."
People who attended a Christmas fireworks display saw plenty of natural fireworks as the storm and the display coincided, providing plenty of spectacular pictures.
A severe thunderstorm warning is current for areas between Lancelin to Gingin to Manjimup to Busselton. This includes people in, near or between Perth, Mandurah, Bunbury, Busselton, and Bridgetown.
These areas are likely to be hit by damaging winds and heavy rain.
The Weather Bureau says there are thunderstorms with very heavy rainfall in a line from just north of Bunbury to Wandering.
The front is moving slowly south.
There are more storms south of this area and they could extend to remaining parts of the warning area during today, the bureau said.
Very heavy rainfall which may lead to flash flooding with one-in-50-year rainfall intensities has been observed in the areas between Mandurah and Harvey.
Storms may be accompanied by damaging winds and heavy rainfall which may cause flash flooding.
Bureau of Meteorology duty forecaster Matt Boterhoven said while some areas experienced slowly accumulated rainfall over the past 12 hours, Mandurah had 30mm of rain in an hour.
Harvey recorded 80.2mm of rain, with 46.2mm falling between 5am and 6am, Myalup received 66.6mm, Serpentine recorded 42.88.mm and 38.6mm fell at Garden Island.
Mr Boterhoven said heavy rainfall and thunderstorms were expected to continue until Friday.
“The mid-level disturbance is going to linger near the west coast today and then eventually later tomorrow it will start moving eastwards and away from the lower-west and south-west districts,” he said.
The Department of Fire and Emergency Services answered more than 100 calls for help overnight, 86 of which were from Rockingham.
Most of the reported damage involved flooding and roof damage.
State Emergency Service volunteers are responding to damage on a priority basis and have asked people to remain patient.
There are currently more than 70 volunteers from nine units working in the Rockingham area and a further six units are being deployed.
They are making temporary repairs to homes, fixing minor roof damage, removing fallen trees, sandbagging areas in danger of flooding and pumping out flood water.
Residents in affected areas are being told to stay away from fallen powerlines, be careful of fallen trees, debris and damaged buildings and check on friends and neighbours.
There is a strong wind warning out today for Perth Local Waters, Ningaloo Coast, Gascoyne Coast, Geraldton Coast, Lancelin Coast, Perth Coast, Bunbury Geographe Coast, Leeuwin Coast, Albany Coast and the Esperance Coast.