North Atlantic storm

40°27.7′N 063°51.5′W

Waves left about 24 Sep 12:34Z, ± 2 h

Placed by 3 buoys, whose own placements lie within 141 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