NEW YORK — Christian Jouret had all but given up hope that his grandfather, Jerry, the man who raised him, was still alive.

It had been nearly a week since the 81-year-old left his mountain home in Big Pine, California, to drive back to his wife in Nevada, but he hadn't arrived.

Finally, after six days, the former Nasa employee was rescued from the snow, where he had survived on some biscotti and a couple of croissants.

"The whole thing was just a miracle," his grandson told the BBC.

"It was hard for us to think a man could do so much with his life, create such a legacy, and then get trapped in his car and die of hypothermia."

Jerry Jouret was caught by the winter storms that have pummelled California this month, dropping 3ft (90cm) of snow in the northern part of the state where his car got trapped.

At least 13 deaths have been reported in the state amid the storms. Authorities say only one can be conclusively tied to the weather, and eight others are being investigated as possibly linked to the cold snap.

On 24 February, Jerry had been driving for 30 minutes after leaving Big Pine on what was supposed to be a four-hour trip back to his family home in Nevada, when he accidentally ended up on a smaller road and his SUV got stuck in a snowbank.

But the 81-year-old did not panic. Instead, he put into practice what he had learned from the many episodes of reality TV show Survivor that he had watched with his wife, Sharon, his grandson said.

Jerry - who was wearing only a light windbreaker jacket - kept warm with a thin quilt and a hotel bath towel that he found in the car.

The mathematician was able to conserve the car battery for three-and-a-half days by periodically turning the vehicle off.

For water, he would roll down the window to eat snow, For food, he turned to the few leftover snacks he had in the car.

"He was surviving on snow, croissants and biscotti," his grandson said.

Things took a turn for the worse when Jerry's car battery died as he was rolling up the car window. It happened two days before he was rescued, leaving him even more vulnerable when night-time temperatures fell to well below freezing.

His rescue was delayed by more bad weather, and as the days went by, frantic family members knew it was a race against time.

"I imagine for him there was a lot of fear that this would be the end of his days," Christian said.

On 9 March, after six days, helicopters finally came to Jerry's rescue - though they almost missed him as pilots nearly ran out of fuel and one mistook the car for a rock, his grandson said.

They hoisted Jerry into the helicopter and flew him to hospital.

There, nurses were surprised to find his vitals completely normal, with no signs of hypothermia. His grandfather was "shouting with joy" to him over the phone, Christian said.

"He's not a super emotional guy, but I imagine he got humbled," he said.

"I cried a lot myself. I didn't realise how much we take these things for granted."

Inyo County Sheriff's Office said the helicopter found the stranded car after a mobile phone signal was traced to an area along Death Valley Road.

"When the crew made their way closer for inspection, a window was lowered and a person began waving from inside the vehicle," said their news release. — BBC