Rescue teams and concerned family members are scouring "challenging" terrain for a third day but have still found no sign of a missing teen bushwalker.
Lily Hooper, 18, left Oakdale in Sydney’s southwest about 8am on Wednesday after telling family she was going hiking in the nearby Nattai National Park.
But she did not return in the evening and could not be reached, despite having sent messages from the park earlier in the day.
A multi-agency search involving police, SES, fire services, volunteers and members of Ms Hooper's family found her car near the Bonnum Pic trailhead.
The search resumed about 7am on Saturday, with authorities yet to find any sign of the teen.
NSW Police said rescue teams were facing challenging conditions.
"It's been challenging - obviously the weather is becoming more and more inclement, that is a consideration for us finding Lily," Hume Police District Acting Inspector Benjamin Carey told reporters on Saturday.
"There is a specific trail that we're focusing in on; however, there's numerous side trails that run off it.
"The terrain out there is extremely rugged - very large escarpments, gorges, thick vegetation, creeks - very challenging for our searching teams."
He said Ms Hooper was an experienced bushwalker for someone of her age and search teams remained focused on finding her.
Helicopters, drones and specialist rescuers including trail-bike riders have been involved in the search.
Defence force personnel also joined efforts on Friday.
Hume Detective Inspector Benjamin Bowles said on Friday authorities were concerned for Ms Hooper's safety.
“We have not been able to fully confirm what supplies (Ms Hooper) had with her at the time but we are still hopeful that we will be able to locate her safe and sound,” he said.
“We don’t have any information to suggest that this is anything other than an overdue hiker.”
NSW Premier Chris Minns told reporters on Friday he was “praying for good news”.
“Our heart goes out to that young walker's family," he said.
"We know this must be heartbreaking and incredibly anxious."
Police have appealed for any members of the public with information to make contact.
Ms Hooper is described as about 175cm tall, of slim build, with blonde hair and blue eyes and was last seen wearing a shirt and shorts.
