menacing

Adjective

• threatening or foreshadowing evil or tragic developments
  • a baleful look
    
  • forbidding thunderclouds
    
  • his tone became menacing
    
  • ominous rumblings of discontent
    
  • sinister storm clouds
    
  • a sinister smile
    
  • his threatening behavior
    
  • ugly black clouds
    
  • the situation became ugly
    

Related words

• Synonyms: 
  baleful , forbidding , minacious , minatory , ominous , sinister , threatening