North Pacific storm

46°30.7′N 137°23.3′W

Waves left about 30 Aug 21:09Z, ± 2 h

Placed by 2 buoys, whose own placements lie within 136 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