North Pacific storm

33°25.2′N 125°09.9′W

Waves left about 16 Sep 19:20Z, ± 3 h

Placed by 4 buoys, whose own placements lie within 172 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