North Atlantic storm

39°01.3′N 062°09.4′W

Waves left about 25 Sep 10:31Z, ± 2 h

Placed by 4 buoys, whose own placements lie within 166 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