North Pacific storm

41°50.5′N 173°31.5′W

Waves left about 5 Sep 10:40Z, ± 2 h

Placed by 9 buoys, whose own placements lie within 473 mi 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