North Pacific storm

47°59.9′N 158°30.1′W

Waves left about 25 Sep 03:01Z, ± 4 h

Placed by 2 buoys, whose own placements lie within 210 nmi 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