North Pacific storm

45°48.3′N 153°08.4′W

Waves left about 22 Sep 11:30Z, ± 3 h

Placed by 3 buoys, whose own placements lie within 230 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