North Pacific storm

02°03.4′N 130°55.3′W

Waves left about 21 Sep 04:34Z, ± 6 h

Placed by 6 buoys, whose own placements lie within 321 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