Supernatural the book of monsters, demons, spirits and ghouls

The Woman In White, part 3

Our dad, after taking out a WiW outside Durant, Oklahoma, in 1991, wrote in his journal that he thought La Llorona was the same kind of spirit the Irish called a bean sidhe, or
Banshee. Sometimes they are dressed in white, sometimes in a winding sheet or burial gown. They wail, they scream, sometimes they sing to signal that death approaches for some member of the household where they are heard. Usually they come in one of three forms, which correspond to the three stages of womanhood (and maybe have something to do with the age of the person whose death is being signaled). A banshee is either a beautiful young woman, a matron, or a corpselike hag. As a hag, she has a link, way back, with notorious English hag figures such as Black Annis, a one-eyed crone, physically strong and with the features of a demon: long teeth, iron claws, and a blue face. She was said to hide in a giant oak that was the sole survivor of the primeval forest. Like many hag figures, she was a cannibal who preferred children, which she ate after flaying them alive. Their skins hung in a cave beneath the tree.
Baba Yaga, from Russian lore, is another example. Living deep in the forest, in a magical hut that moved around on chicken legs, she often ate children, but unlike Black Annis, Baba Yaga could be an important source of magical help for a hero or questing child. If you asked her the right kind of question, or caught her in the right mood, she might help you on your errand instead of making a meal of you.
The banshee often appears crying as she washes bloody clothes by a river-usually the clothes of someone about to die. Also, she can appear as a crow, rabbit, or a weasel.

The banshee is more of an omen spirit than the woman in white tends to be, but the relationship is there. At least in the Jericho case, seeing Constance Welch was a sure sign that you were going to die.