For me, it's about letting your rain 'do its thing'. Don't worry too much.
Think about it for a moment. How many normal circuits have you memorized? I could probably do the entire F1 grid in my head, 20-30 kart circuits and a whole bunch of others. Maybe a 200 miles or so. if you drove each track successively you could probably do a 100 miles before you even come close to making a wrong turn. That's an astonishing feat and far outweighs learning the Nord.
I think, like others have said maybe compartmentalise the track. See it as three of four separate entities, and just put the laps in. Your brain is much better at memorising stuff like this.