puntosaurus
Chances are you are going to impact some sort of settlement in the event of a power failure regardless of what height you're flying at in those weather conditions, and regardless of how good your Radalt is, so most likely "failure of a power unit", but again if you can't maintain visual with the surface all the way along your "VFR" route then you shouldn't have gone in the first place? Too many people think because they can see well ahead and laterally then it's fine to continue, until that one time when it will all go quiet, with no safe option below
Same as at night..........................