North Atlantic storm

27°30.2′N 041°43.0′W

Waves left about 22 Sep 12:18Z, ± 5 h

Placed by 2 buoys, whose own placements lie within 297 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