North Atlantic storm

38°23.4′N 050°43.3′W

Waves left about 28 Sep 12:24Z, ± 3 h

Placed by 4 buoys, whose own placements lie within 226 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