How accurate are weather forecasts?

I've often wondered how accurate a forecast is, especially when they forecast 10 days out.  Who tracks these numbers to see if they're even worth paying attention to? Well, of course there's a website (scroll down for the weather accuracy data), and the numbers are better than I thought.  Read the page for the details, but this graph shows that the weatherman's prediction up to 7 days out was better than the almanac, and better than assuming today's weather will repeat itself for so many days (persistence). TE