na-adjective, noun which may take the genitive case particle 'no'
stormy; threatening (weather)
Describes weather that looks like it will become stormy, or figuratively a situation that seems about to turn turbulent.
The sky looks stormy, so you'd better take an umbrella.
The meeting was stormy, with opinions clashing fiercely.
Compound of 荒れ (are, 'stormy/rough', continuative form of 荒れる) and 模様 (moyō, 'pattern/appearance').