From the first picture I was thinking bay roan, because her head looks dark, but the color is changing on her head as well. Her dark points and mane and tail will eventually turn white. Some horses turn quickly, and others quite slowly. I like seeing the progression of the color change from year to year in the slower-graying horses.
Her tail is a give away sign to her color. The fact that it is half white is indicating grey. Here head and legs would not be greying either if she were a roan.