A minute or so later, the sun goes down. It is abruptly very dark, the only natural illumination being the flashes of lightning.
The storm intensifies. The rain begins to come down at a tremendous rate. With alarm, you notice that the sand of your island is starting to turn to mud and wash away into the sea.
Just when you are verifying this, you see far off the the west, previously hidden by the swells, a couple faint lights. They are moving, and your assumption is that they are the guide lights for a ship, one fore and one aft, but they are far too far away to make out the ship itself (if ship it truly is).
It becomes clear, as the lights continue moving, that they will pass by within a couple hundred yards of the island in about half an hour, but not near enough to see you. You estimate you have about an hour before the island totally washes away and leavs you adrift in the sea.