North Pacific storm

48°51.1′N 143°33.6′W

Waves left about 27 Sep 02:20Z, ± 2 h

Placed by 7 buoys, whose own placements lie within 402 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