Parts of Sydney were put on alert for severe storms for the second day in a row on Wednesday with residents urged to prepare for damaging winds and large hail stones. Forecasters also warned of heavy rain in the state’s south-east on Thursday.

The Bureau of Meteorology issued a severe thunderstorm warning on Wednesday afternoon for parts of western Sydney, the Hunter, the Illawarra, the Southern Tablelands, the Central West Slopes and Plains and the South West Slopes.

“A surface trough over NSW and a broad upper trough over eastern Australia will aid the development of thunderstorms across NSW this afternoon,” the bureau said in a statement.

“Severe thunderstorms are likely to produce damaging winds, large hail stones and heavy rainfall that may lead to flash flooding in the warning area over the next several hours.”

Central Sydney, at Observatory Hill, recorded almost 10 millimetres of rain within 30 minutes from 5.30pm.

The severe weather alert for Sydney was cancelled by Wednesday evening but warnings remained in place for parts of the Hunter, Mid North Coast, and northern regions.

Bureau climatologist Agata Imielska said humid air from northern Australia was feeding into a low-pressure trough over NSW.

She said Wednesday’s rain might impact already saturated catchments in the state’s north and central west, which were recently affected by major flooding.

“We have seen severe thunderstorms impact much of NSW over the past 24 hours,” she said.