North Pacific storm

31°10.0′N 131°38.0′W

Waves left about 29 Sep 07:31Z, ± 2 h

Placed by 4 buoys, whose own placements lie within 269 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