North Pacific storm

51°13.3′N 179°56.1′E

Waves left about 24 Sep 13:29Z, ± 1 h

Placed by 12 buoys, whose own placements lie within 728 km 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