North Atlantic storm

43°41.8′N 042°48.4′W

Waves left about 23 Sep 12:18Z, ± 3 h

Placed by 5 buoys, whose own placements lie within 236 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