North Atlantic storm

42°49.4′N 007°20.9′W

Waves left about 19 Sep 16:21Z, ± 7 h

Placed by 3 buoys, whose own placements lie within 414 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