Last week I said I had an Armstrong cycle low from March 2003...

Last week I said I had an Armstrong cycle low from March 2003 due on last Wednesday +/- 1 day.

In fact I was lazy and didn't check properly with a spreadsheet.

I should have thought about it when I scanned back and saw the last few cycles were a bit late.

The reason is that each cycle is X days plus a part of a day. So every few repeats the turn comes in another day late.

So Friday was spot on but that means since it just added a day next time shouldn't need too.