North Pacific storm

01°23.0′N 139°29.5′W

Waves left about 2 Sep 20:21Z, ± 3 h

Placed by 5 buoys, whose own placements lie within 213 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