North Pacific storm

45°49.9′N 152°46.8′E

Waves left about 22 Sep 23:59Z, ± 3 h

Placed by 5 buoys, whose own placements lie within 630 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