North Pacific storm

09°36.8′N 159°00.5′W

Waves left about 27 Sep 08:42Z, ± 3 h

Placed by 3 buoys, whose own placements lie within 285 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