BOM downgrades severe thunderstorm warning as rain brings bushfire relief across NSW

Updated

The Bureau of Meteorology (BOM) has downgraded its warning for severe thunderstorms across parts of Sydney and the Blue Mountains as conditions have eased.

Key points: The Rural Fire Service says it's seen "good falls" on some firegrounds

However, there are fears bushfire debris could prevent water from being absorbed into soil

A severe thunderstorm warning has been issued for several areas

It said severe thunderstorms were no longer affecting Sydney, Newcastle and Wollongong or surrounding areas, however the situation was being monitored closely as it was possible further severe thunderstorms could develop.

A more general warning remains in place for areas stretching from the South West Slopes and Plains and Snowy Mountains districts to the Mid North Coast.

The NSW State Emergency Service (SES) said it had received around 200 callouts across the state, mostly for fallen trees and leaking roofs.

SES Spokesperson Andrew McCullough said much of the damage was in the north of the state, around Port Stephens and in some bushfire-affected towns on the South Coast, while there were 25 callouts at Parkes in the state's Central West.

"We're seeing isolated and localised thunderstorms bringing really heavy downpours of rain in some locations so it's really important that motorists make safe decisions and stay out of the floodwaters while they're driving their vehicles," he said.

Heavy rain has already fallen in several regional centres including Tamworth and the Hunter, and thunderstorms will persist throughout the evening.

The BOM warned the rainfall in fire affected areas may contain debris such as ash, soil, trees and rocks.

Trees that have been damaged by fire are also more likely to fall, BOM has warned.

Ausgrid said power was out for 3,000 customer in Port Stephens, Newcastle and Lake Macquarie after severe storms swept through the Hunter.

More than 10,000 lightning strikes were recorded in the Hunter during the storms.

The rain has offered some relief for fire crews, but there are concerns the wet weather could cause landslides, flash flooding and contaminate water.

Cool, wet conditions are good news for firefighters who have been battling hundreds of blazes across the state since September.

A Rural Fire Service (RFS) spokesperson said despite the rain a number of fires continued to burn.

"In some places, the rain has been very beneficial and has assisted in seeing fires moved to 'out' — particularly up in the Northern Tablelands area," the spokesperson said.

"In saying that, it is not state-wide, and a number of fires will continue to burn as a small amount of rainfall is not enough, and can hinder important containment work including backburning."

The BOM predicted between 30 and 80 millimetres of rain would fall in some areas between now and Sunday.

The heavens opened over Sydney Thursday morning and about 20-40mm is set to fall over the next few days.

Hunter farmer Doug Robertson said the rain had given everybody a mental lift.

"It's been a long time coming. We're into the third year of what I would call a solid drought.

"If it keeps doing what hopefully it's forecast to do, it will mean the world to us.

"From a mental point of view that load starts to lift. You can see the light again."

Meanwhile, the RFS said there had been "good falls" across some firegrounds.

The downpour is a result of a deep inland trough moving through the state which is drawing humid air into the system.

RFS Inspector Ben Shepherd said he was expecting around 10-15mm to drop on most firegrounds.

However, BOM forecaster Abrar Shabren said debris, which has remained on firegrounds for weeks, could prevent water from being absorbed into the soil.

It could also lead to a significant run-off of ash, soil and other debris which have accumulated in the past months.

"Flash flooding is generally a concern with thunderstorms and ponding of water on roads," Mr Shabren said.

"Depending on how much vegetation is left, how much bushfire the ground has gone through, that can also add to the impact of flash flooding as well."

Mr Shabren said bushfire areas, particularly in elevated regions, were also "vulnerable" to landslides and toppling trees during thunderstorms because fires would have weakened the vegetation.

The amount of rainfall is also unlikely to replenish dams or break the drought in any regions, according to Tony Weber from WaterNSW.

Warragamba Dam, which supplies water to more than 5 million people living in Sydney and the lower Blue Mountains, is at 43.7 per cent capacity.

Topics: rainfall, bushfire, fires, sydney-2000, nsw

First posted