The speaker visits a patch of forest, a one-acre area flattened by wind 38 years ago, and finds it fully grown back. The poem moves like a walk: a few observations, then a question or thought that surfaces in between. "How big was that wind" is the speaker trying to picture the force that did all this, working backward from what remains. Twin basswood trunks spread wide, and a beech limb has curled back into the tree, as if the forest has quietly absorbed its own wound.
The mood is calm but awed. Nothing is dramatic on the page, yet the short lines and plain statements leave room for the storm to feel enormous. The detail that people heard the wind from half a mile away makes the force more real, and the closing phrase, "the hollow's own howl," gives the place a voice. The speaker seems to feel both respect for the storm and a quiet wonder at how healing looks after nearly four decades.