Its gunna be windy on that day so there will be lots of kites in the air,
thus reducing the earth's wind resistance slowing its spin rate making the ocean surge in the opposite direction. ie longer high tide.
Damn those pesky young kiters, the hot women that chase them and the huge environmental foot print they make.
That, or,
there is a windsurfer comp on somewhere that day??? That amount of overweight old blokes in the ocean at the same time,
the massive water displacement would be huge causing the lonnnnggg high tide??
If so, I think we should all write a proposal to local councils to not allow poledancer comps to coincide with king tides, to stop the dune erosion issues.