North Atlantic storm

44°49.4′N 039°52.7′W

Waves left about 23 Sep 09:53Z, ± 6 h

Placed by 3 buoys, whose own placements lie within 119 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