Final answer:
In the novel The Alchemist by Paulo Coelho, Santiago sees a flock of black crows as a portentous omen in the Al-Fayoum oasis.
Step-by-step explanation:
In the novel The Alchemist by Paulo Coelho, a portentous omen that Santiago sees in the Al-Fayoum oasis is a flock of black crows. This omen signifies something ill or negative to Santiago. The crows are often associated with death or bad luck in various cultures, and their appearance foreshadows a challenging and dangerous journey for Santiago.