North Pacific storm

39°49.5′N 169°11.5′E

Waves left about 31 Aug 20:02Z, ± 3 h

Placed by 4 buoys, whose own placements lie within 513 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