Final answer:
The image of 'evil things in robes of sorrow' in the first stanza of 'Sir Patrick Spens' foreshadows a tragedy concerning the monarch's high estate.
Step-by-step explanation:
The image in the first stanza of "Sir Patrick Spens" that forebodes a forthcoming tragedy is the mention of evil things dressed in robes of sorrow assailing the monarch's high estate. This suggests a looming disaster that will affect the king's noble position and implies that the narrative will follow a dark and possibly disastrous course. This foreshadowing sets the mood for the rest of the ballad, aligning with the themes of inevitable doom and melancholy that are characteristic of many tragic narratives.