I’ll assist on the thread drift after saying “well done” to our resident ultra-distance runner(s). I have done all my winter running in Minnesota and Chicago. This is my general practice for colder runs, dependent on other factors (pace, snow/rain, wind):
>50F: t-shirt or jersey, split shorts.
35-50F: long underwear top (I like wool), light gloves; compression shorts, split shorts.
20-35F: long underwear top, short-sleeve or jersey, light gloves, stocking cap; tights, split shorts.
0-20F: long underwear top, short-sleeve shirt, cheap windbreaker, windproof gloves/mitts, stocking cap, neck gaiter; compression shorts, tights, split shorts.
<0F: add thin pants.
Shoes and socks generally don’t change, though I might put on longer socks to tuck into tights. I don’t think I’ve ever been too cold in this, though my runs are generally 30-90 minutes year-round. I think if I were doing 20+ mile runs in the winter I would do a couple loops to allow return to a central point for hot drinks/refueling.
Deceleration is much more difficult for you and for cars on snow/ice, so be careful.