North Pacific storm

30°15.0′N 131°31.3′W

Waves left about 29 Sep 07:26Z, ± 3 h

Placed by 3 buoys, whose own placements lie within 122 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