Gulf of Alaska storm

52°50.2′N 151°54.7′W

Waves left about 23 Sep 12:15Z, ± 5 h

Placed by 2 buoys, whose own placements lie within 290 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