North Atlantic storm

41°47.8′N 061°40.7′W

Waves left about 14 Sep 14:51Z, ± 2 h

Placed by 6 buoys, whose own placements lie within 144 nmi 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