North Pacific storm

19°34.7′N 150°38.9′W

Waves left about 26 Sep 10:06Z, ± 2 h

Placed by 2 buoys, whose own placements lie within 417 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