North Pacific storm

38°25.2′N 166°11.6′E

Waves left about 17 Sep 03:19Z, ± 3 h

Placed by 9 buoys, whose own placements lie within 1019 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