I can't confirm it, but it intrigues me. The 46-day ECM charts, from which the extended forecast draws, are updated on Mondays and Thursdays, so that's when you'd expect that part to change. By and large it does only change a couple of times a week, but quite often on the Tuesday and Friday instead (IIRC today's extended is materially different from yesterday's offering). I'd always assumed that was because they were waiting for the Chief Forecaster's input, but perhaps they really are delaying it...
A source would be handy.
Originally Posted by: Retron