North Pacific storm

47°36.3′N 149°11.0′W

Waves left about 26 Sep 23:39Z, ± 3 h

Placed by 4 buoys, whose own placements lie within 454 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