But that's exactly what happened Sunday afternoon, when the 18-year-old from Pacifica got separated from his friends at the Sierra-at-Tahoe resort and realized he was alone with night, and snow, falling around him.

Rescuers found him about 12 hours later, around 3:30 a.m. Monday. Except for a cold, he's in perfect health.

``It was pretty weird, actually,'' said Stack, who was reached at his home Tuesday. ``It kind of felt like it wasn't really happening.''

Stack graduated this year from Terra Nova High School in Pacifica and now works as a hotel clerk in town.

According to his buddy Ali Durkin, Stack spent Sunday snowboarding with four friends, including Durkin, and at about 3:40 p.m. had snowboarded ahead of them on a run, but only by about six feet.

The group decided to cross through the trees to another run, but Durkin said Stack couldn't because there were too many rocks and trees in his way.

So Stack went straight down the mountain and took the lift up again because he thought his friends would do the same. Instead, they decided to wait for him at the car, which they had earlier planned on doing, Durkin said.

But Stack didn't show up. Temperatures were dropping.

Stack said he began to walk and kept walking through the snow and trees.

Around midnight, he hunkered down under a tree, digging a shelter of sorts, but it began to snow, so he kept moving. After a few minutes, Stack found a group of about four vacation cabins shuttered for the winter. In the moonlight, he tried to break in, but found the windows were covered with metal sheets, he said.

Stack was able to get into a nearby storage shack, which was not big enough for him to stretch out in, but shielded him from the snow. In his wet clothes, he sat and thought, drifting in and out of sleep, he said.

``I was thinking about everything,'' he said. ``Just life in general. I was thinking about if I could get up the next day.''

At about 3:30 a.m. Monday, he heard whistles, and saw the flashlights of two rescuers who were on cross-country skis. It turned out he was only 15 minutes from Highway 50, in Sayles Canyon, about 12 miles southwest of Lake Tahoe and just outside the resort, said El Dorado County sheriff's deputy Mike Sukau.

``They brought me back in an ambulance and checked for frostbite,'' Stack said. ``They thought I would have it for sure. I was telling them I was fine.''

After changing his clothes and having some hot soup, Stack was returned to his buddies, who joked with him the whole way home, Durkin said.

From now on, Stack's friend said, ``When I'm with him I'll bring him a walkie-talkie.''