North Pacific storm

46°30.5′N 168°39.4′E

Waves left about 9 Sep 23:39Z, ± 3 h

Placed by 2 buoys, whose own placements lie within 276 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