North Pacific storm

40°15.2′N 141°04.2′W

Waves left about 25 Sep 21:32Z, ± 2 h

Placed by 3 buoys, whose own placements lie within 272 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