BUFFALO — Liza Smith knows snow. But she had never seen anything like what she encountered on Tuesday morning on the New York State Thruway.

Just outside of Buffalo, she ran smack into a towering wall of white, the edge of one of the most powerful winter storms ever to descend on the region.

Within hours, several people were dead. As five feet of snow blanketed the region, schools and government offices were closed, sporting events were postponed, and hundreds of people, including Ms. Smith, were stranded across a stretch of western New York just south of Buffalo.

Ms. Smith and her daughter, Chloé, stopped in the Thruway’s left lane and were trapped in the car for more than a day. With spectacularly large flakes continuing to fall furiously outside, burying the car ever deeper, she called 911 and the Thruway Authority.