For 20-50 degree weather...

I just bought a fleece jacket from predator that will do the trick, its a heavy fleece.
That will go over a Silent Weave shirt, underarmor cold gear, and a cotton teeshirt.
I'd probably pack in a goose down or fleece vest to throw on if I got chilly


And by far the best thing for keeping you warm is a Fleece Neck Gaitor... I never leave home w/o mine in colder weather... makes a huge difference