North Atlantic storm

25°42.8′N 025°43.1′W

Waves left about 21 Sep 05:58Z, ± 6 h

Placed by 4 buoys, whose own placements lie within 578 km 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