Its hardly definitive but this evening news account has more detail in it than the Seattle Times article or the speculation here. http://www.kirotv.com/news/25536602/detail.html

She survived by staying awake, moving constantly, and (I suggest) staying confident and upbeat, living (a la Laurence Gonzales' observations on survivors) to see her kids again. The garbage bag isn't mentioned on the TV segment. It probably played a role, but Ms. Manko got lucky with the weather, and (barely) didn't exceed her limitations. The last part of the news account says her temperature was only 90 degrees when she arrived at the hospital. So there's an end even to luck and pluck. She's from the Ukraine though, tough people!

Not to nit pick or to put her down, I don't - but heading up to Lake Ingalls for a day hike is at least a 5-6 hour affair, a prudent hiker would have taken more gear with them at any time of the year, and she left late in the day with bad weather known to be approaching. Situational awareness...