Foreboding always suggests a negative outcome, never a positive one. The soldiers had a foreboding of defeat before the battle began.
Pro Tip 2/3
Intensity varies
The intensity of a foreboding can range from a vague feeling to a strong conviction. She felt a slight foreboding when she saw the abandoned car.
Pro Tip 3/3
Often vague
A foreboding doesn't always specify what the bad event will be, just that danger looms. As the door creaked open, an unexplained foreboding chilled the room.