North Pacific storm

38°12.6′N 144°23.0′W

Waves left about 25 Sep 04:35Z, ± 3 h

Placed by 2 buoys, whose own placements lie within 273 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