Glee! the great storm is over
Disproportionate celebration
That exclamation mark is doing dark work—celebrating four survivors while forty drowned. The forced cheerfulness makes the horror worse.
Spinning upon the shoals
Bodies caught in underwater sandbanks, turning in the current. The euphemism makes it more disturbing than graphic description would.
Winter shakes the door
Maritime New England detail—winter storms rattling doors trigger shipwreck stories. The door-shaking becomes the sea still claiming its dead.
Only the waves reply
The dead can't answer. The sea keeps the forty. Notice how the poem ends with permanent silence, not comfort.