Gulf of Alaska storm

51°38.1′N 139°12.9′W

Waves left about 27 Sep 12:17Z, ± 3 h

Placed by 3 buoys, whose own placements lie within 244 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