He felt it.

And with that in his mind he waited, strong as steel in his conviction, capable of withstanding any strain endurable by the human frame.
The wind blew in puffs, grew wilder, and roared through the willows, carrying bright sparks upward.

Thunder rolled down over the river, and lightning began to flash.

Then the rain fell in heavy sheets, but not steadily.

The flashes of lightning and the broad flares played so incessantly that Duane could not trust himself out on the open river.
Certainly the storm rather increased the watchfulness of the men on the bluff.