Use 'portentous' to describe settings or events that hint at impending danger or trouble. The silence of the battlefield was portentous, hinting at an upcoming attack.
Pro Tip 2/3
Imminent Warning
'Portentous' indicates a strong likelihood that something bad will happen, often used in narratives. She had a portentous feeling as the sky grew dark.
Pro Tip 3/3
Subtle Intuition
Applies to describe a vague, unsettling premonition about future events. His sudden departure was portentous of troubles within the company.