I was recently directed in the way of
http://www.weatherjack.com/ , which is mostly aimed at glider pilots. But there are a huge array of links there, and it will certainly be possible to get the info you are looking for.
For general WX info, try
http://redkite.net/weatheraction/5DayShow.tmpl . It's Piers Corbyn's 5 day weather view, and although the info is not very detailed, it is normally very accurate. Don't mention to the Met Office that you think he produces good forecasts... his techniques are somewhat shunned!