The storm raged more and more ferociously as the night went on. Harry couldn't sleep. He shivered and turned over, trying to get comfortable, his stomach rumbling with hunger. Dudley's snores were drowned by the low rolls of thunder that started near midnight. The lighted dial of Dudley's watch, which was dangling over the edge of the sofa on his fat wrist, told Harry he'd be eleven in ten minutes' time. He lay and watched his birthday tick nearer, wondering if the Dursleys would remember at all, wondering where the letter writer was now.
Five minutes to go. Harry heard something creak outside. He hoped the roof wasn't going to fall in, although he might be warmer if it did. Four minutes to go. Maybe the house in Privet Drive would be so full of letters when they got back that he'd be able to steal one somehow.
Three minutes to go. Was that the sea, slapping hard on the rock like that? And (two minutes to go) what was that funny crunching noise? Was the rock crumbling into the sea? One minute to go and he'd be eleven. Thirty seconds. . . twenty. . . ten. . . nine –– maybe he'd wake Dudley up, just to annoy him –– three. . . two. . . one. . .
(Harry Potter and the Sorcerer's Stone)
The modality would is very hard to guess what it means. Would you pick the right meaning in OALD?