ominous

an event or object that is believed to be a warning of a future bad event

a statement or event that serves as a serious warning of danger or trouble

a dark cloud that suggests a storm or bad events are coming

a quietness that is unsettling because it suggests something bad has happened or is about to happen

a suggestion within something that indicates a bad outcome is likely

a low, deep, continuous sound that signals danger, such as distant thunder or an earthquake

the threatening possibility of something very unpleasant that might happen in the future