North Pacific storm

40°48.8′N 167°49.1′E

Waves left about 31 Aug 18:45Z, ± 3 h

Placed by 5 buoys, whose own placements lie within 497 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