As for wind forecasts, I started using Windfinder after several Winni sailors recommended it. I find it to be the most reliable indicator of what the day on the lake will be like.
Living on the east end of a long open stretch of water, I find that the most useful part is the gust forecast. Anything over 10 mph is usually a pretty rough day on the lake. But as noted above, it can vary during the day also.
http://www.windfinder.com/forecast/new_durham_alton