nar nar = from gnarly meant in the sense of "great"

pow pow = is powder, powdery snow

cuttin = skiing (i.e. leaving a trail behind you after cutting through the snow)

freshies = means fresh, new; not clear in this context, it could refer to "fresh snow" or "fresh tracks"

nippy nips = depth of snow is up to your nips (nipples) and you are cold/excited/goosebumps so your nips are nippy

this is generalized "california surfer talk"; the type of western man who surfs also snowboards, dirt bikes, jet skis, etc as well as clings to a teenaged hangout burnout lifestyle