For a 55 run, I would have gone in a short sleeve and Sparkle Skirt. I am going to wear that tomorrow at my race even though it's going to be in the low 40's when it starts... when it ends, it'll be closer to 50-52 and I tend to run hot/sweaty. I am crossing my fingers I'm not too cold.
In the colder weather, I wear capris in the 30's usually with a half zip with a short sleeve shirt underneath. In the 20's, I have some fleece lined tights (Sugoi brand) and will layer more under my half zip (either a long sleeve or a short sleeve then long sleeve if it's getting into the lower 20's). I also have a NB jacket that I got last year that I liked for low-20's, but it was very snug last year with shirt layers under it (I still have a chunk of weight to lose, and am right on the edge of being able to fit into most brands XL gear as far as fitted stuff like that goes), and I have gained back 10-12 lbs in the past year, so, I do not think that I'll be wearing that jacket this winter.
I have some heavier/thicker Sugoi tights for low 20's or 10's, and my jacket should have also been ok in the 10's, but I still get real cold in those temps, especially in the butt. I need butt warmers build into my tights.