I certainly see no issue with the cable above.
The inside of a raceway is still a wet location if it is outside and THWN is a wet rated conductor. What difference does it make if the rain is getting into the MC/FMC? Is it any wetter than a buried raceway is filled with water?

I have seen plenty of regular aluminum MC outside. You just need the cables arranged so they don't fill the boxes with water (typically bottom entry)


Greg Fretwell