North Pacific storm

34°47.0′N 152°31.2′E

Waves left about 22 Sep 10:42Z, ± 5 h

Placed by 2 buoys, whose own placements lie within 74 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