North Atlantic storm

27°51.7′N 048°31.4′W

Waves left about 24 Sep 12:39Z, ± 6 h

Placed by 2 buoys, whose own placements lie within 221 mi of it

Each buoy places the storm from how its swell's period shortened as it arrived: the longest waves travel fastest. Fronts are drawn at deep-water group speeds along great circles, and stop at land. How it is worked out