North Pacific storm

48°38.2′N 158°00.1′W

Waves left about 27 Sep 02:12Z, ± 5 h

Placed by 2 buoys, whose own placements lie within 61 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