Warragamba dam could spill over the Mother’s Day weekend amid severe weather warnings on the east coast, and after a tornado tore through the West Australian city of Bunbury, injuring two people.
WaterNSW issued a warning on Friday that the Warragamba dam was nearing capacity after several days of rainfall, and that a spill event was “likely in coming days”.
The Bureau of Meteorology has forecast 35mm of rain in the catchment area over a 48 hour period, meaning the dam could reach a peak-spill rate of about 40GL/day.
WaterNSW said this was significantly below the spill peak in early April, which was more than 200GL/day.
If there is over 60mm of rain in the 48 hours, then the spill peak would be closer to 100GL/day.
Other dams in the greater Sydney area will also continue to spill, the bureau warned, including Cataract, Nepean, Woronora, Tallowa, Greaves Creek, Medlow Bath, and Middle Cascades. Avon Dam was also at risk, and was at 93% of capacity.
There have been more than 50 spills of Warragamba dam since 1960.
The forecast came after a tornado was reported in south Bunbury on Friday afternoon.
Two people were reportedly taken to hospital after the tornado damaged buildings at the Bunbury PCYC and the Bunbury regional prison.
A severe thunderstorm warning was later cancelled for the area but residents were advised to avoid debris and fallen powerlines.
The bureau on Saturday said a coastal trough around the south-east coast of New South Wales was forecast to deepen into a coastal low on Saturday night or early Sunday morning.
Heavy rainfall may lead to flash flooding in the northern parts of the South Coast, the southern parts of the Illawarra, eastern parts of the Southern Tablelands and far north-eastern parts of the Snowy Mountains on Saturday morning, and persist into Sunday.
Rainfall of between 80 to 120mm was likely, and isolated falls of up to 200mm were possible over the ranges, BoM said. The heavy rainfall is forecast to ease during Sunday evening.
“This is rain falling on already wet ground so the water will pool and cause flash flooding, so if you’re in these areas please take care,” meteorologist Christie Johnson said.
Nowra, Batemans Bay, Moruya Heads, Ulladulla, Narooma and Araluen are expected to be hardest hit.
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SES NSW has already responded to 240 incidents in the 24 hours to 3pm due to wet conditions in the Illawarra, South Coast and Sydney areas.
The NSW State Emergency Service warned residents on Friday to prepare and take action to minimise damage to property.
With heavy rain forecast across several regions this weekend, the SES urged residents to take measures to ensure their safety and minimise potential damage to property.
“Flash flooding can occur rapidly and without warning, posing a significant risk to life and property. People should where possible, stay indoors during heavy rainfall and avoid driving or walking through flood waters,” NSW SES assistant commissioner Nicole Hogan said.
A bushwalker has survived after spending a night lost in the Blue Mountains as the area was pummelled by heavy rain.
The 38-year-old was reported missing at 11.30am on Friday and was found by a team of specialist search-and-rescue professionals just under 24 hours later, SES NSW said.
Senior group officer Caro Ryan said the woman was not injured and was checked over by paramedics before walking out of the bush with the rescuers.
“We located her in bushland near Katoomba and helped warm her up because she had been out in the cold and rain overnight,” Ryan said.
“We know the areas people often get lost, the mountain passes and the tricky pinches.”
Up to 10mm of rain was also forecast for the northern parts of Victoria and southeastern parts of Queensland on Saturday.