North Pacific storm

45°24.7′N 173°16.0′W

Waves left about 18 Sep 05:52Z, ± 2 h

Placed by 6 buoys, whose own placements lie within 439 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