North Pacific storm

46°23.7′N 133°43.6′W

Waves left about 28 Sep 01:21Z, ± 2 h

Placed by 3 buoys, whose own placements lie within 140 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