North Atlantic storm

40°02.9′N 053°55.1′W

Waves left about 24 Sep 13:26Z, ± 3 h

Placed by 3 buoys, whose own placements lie within 389 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