The young woman lay stiff on the porch in the piercing cold of a subzero morning. Her bare hands were pale white and swollen to three times their normal size, skin split from palm to finger. She was breathing. She was shaking. She was not conscious when a passer-by spotted her and came to her aid.

College student Alyssa Jo Lommel apparently had survived outside overnight in temperatures that dipped to 17 below early Saturday morning near the University of Minnesota Duluth campus, police said. She wore UGG boots, jeans, a sweater and a medium-weight jacket.

Lommel was flown to Regions Hospital in St. Paul, where she was in critical condition on Tuesday. Lommel’s parents, Jay and Teri Lommel of St. Cloud, told the St. Cloud Times their daughter suffered significant damage to her hands and feet and could lose one or more of them.

It still isn’t clear exactly why she ended up Saturday at the house next door to her own.

According to a police report released Tuesday, Lommel, a 19-year-old sophomore, had been out with friends Friday evening. She got home from work about 5:30 p.m. or a little later, ate a bagel for dinner and poured herself a drink, her roommate told police. About 10:30, she and a roommate got a ride to a friend’s house, where they played a drinking game with cards called “ride the bus.” Lommel lost several rounds and had to take a shot.

Friends told police that Lommel’s drink of choice was tequila. A Friday afternoon update on her Twitter account said “tequila shots tonight.” A roommate later told police that Lommel had been taking medication daily.

Sometime after 11 p.m., the group went to another party, the report said, but Lommel soon told her roommate she was leaving.

The roommate stayed at the party while friends picked up Lommel, drove her to the front of her house on Woodland Avenue near campus, unlocked the doors and watched her get out. She was buzzed but not intoxicated, friends told police. She was talking and walking.

They drove away without watching Lommel go inside. It was about midnight.

Windchills reached 36 below overnight, according to the National Weather Service. Two of Lommel’s roommates arrived home without noticing anything amiss, one a few hours later, another in the daylight of the morning.

A woman riding down the street with her boyfriend about 9:30 a.m. Saturday happened to spot Lommel. She called police, telling them she’d found an unconscious young woman outside on a porch.

Authorities arrived to find Lommel lying on her right side, “extremely cold and hypothermic,” the police report said. The house was empty, its occupants out of town.

As authorities looked for blankets to cover Lommel while awaiting an ambulance, police found her wallet and keys and noticed tracks from her boots in the snow around the house. The tracks wound to a garage, around a parked car and a deck in back. Some tracks were “up near the house as if to use the house as a crutch to hold onto. They then had impressions as if the person was falling down, getting back up and crawled around the southwest corner facing Woodland Avenue,” the police report said.

Authorities found Lommel’s cellphone on the back deck.

“We are grateful for all the thoughts and prayers for our daughter,” Jay and Teri Lommel said Tuesday, while also requesting privacy “so that we may focus on her healing.”

In a statement, university officials encouraged students to contact campus health services for counseling. They urged caution in the extreme cold by traveling in groups, checking in with others and dressing in layers.

“Our hearts are with Alyssa and her family in these difficult times,” the statement said.

Staff writer Joy Powell and the Associated Press contributed to this report.