BOM warns of flash flooding as rain brings bushfire relief across NSW

By Kevin Nguyen

Rain falling across NSW is offering some relief for fire crews battling blazes, but there are concerns the wet weather could cause landslides, flash flooding and contaminate water.

Key points:

·         The RFS says it's already seen "good falls" on some firegrounds

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

·         The forecast rain is unlikely to replenish dams or break the drought in NSW

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

The Bureau of Meteorology (BOM) predicted between 30 and 80 millimetres of rain would fall in some areas between today and Sunday.

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

Meanwhile, the NSW Rural Fire Service (RFS) said there were already "good falls" across some firegrounds.  RFS Inspector Ben Shepherd said he was expecting around 10-15mm to drop on most firegrounds, with the highest falls predicted in the Hunter.

"This won't be enough to extinguish the fires, but will take the sting out of them," he said.  "It's the most positive forecast the RFS has had in months and will give crews a chance to regroup and work on containment lines."

However, BOM forecaster Abrar Shabren said heavy rain 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.

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.