Investigators say Celine Cremer, 31, was last seen at the Philosopher Falls track in Waratah near Cradle Mountain on June 17 and was equipped for a light day walk before she disappeared.
Her family reported her missing on Monday after becoming concerned for her welfare following more than a week of no contact.
A car belonging to Ms Cremer was found in the falls car park and was first spotted by witnesses about June 20, the same time the last signal from her phone was picked up in the area by police.
Searchers are battling freezing temperatures, snow, rain and dense bushland.
Tasmania Police Inspector Anthea Maingay said the challenging weather was expected to worsen over coming days.
"The search so far has included ground search crews and police drones and helicopters, but unfortunately no further signs of Celine have been located since her car was found in the Philosopher Falls car park on Tuesday," Insp Maingay said on Thursday.
"Unfortunately, we have received expert medical advice that indicates the recent conditions are not survivable for the length of time that Celine is thought to have been exposed in the wilderness.
"We remain in close contact with Celine's family and our thoughts continue to be with them."
Rescue crews continue to search the area and the Philosopher Falls walking track remains closed.
Ms Cremer had been living in Tasmania for the past six months and intended to make her way to Victoria this week.
Anyone with information is being urged to contact Crime Stoppers.
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