North Atlantic storm

38°43.1′N 016°05.8′W

Waves left about 20 Sep 17:52Z, ± 10 h

Placed by 2 buoys, whose own placements lie within 414 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