Here are some links to the weather forecasting sites I use

Surface pressure charts - If you want to learn about the weather or understand what is happening when you are out then always look at a surface pressure chart. I often download the pressure chart onto my phone as a wallpaper for a days walk to remind me what is going on. They look really complicated but are actually quite simple. Weather forecasts are usually right about what will happen, the thing they find difficult is predicting how long the different bits of weather will last. If you compare your surface pressure chart with your forecast it helps you to know why they are saying it will do what they predict and will help you tell if the weather system is passing faster or slower than predicted. Use these charts with our flow chart when you are out too.

Mountain Weather Information service - Mountain Specific Forecasts for the UK. Often viewed as being a bit pessimistic. 

XCWeather

Yr.NO - Norwegian site. Have some great apps and widgits for Android phones (and maybe other platforms)

Animated surface pressure (and other indicies) charts. Beautiful charts that clearly illustrate wind running anti-clockwise around low pressure and clockwise around high pressure. Can you work out where the fronts are? Take a look then check using the met office surface pressure charts.

Animated wind speed chart - Click on the word 'Earth' to move forward in time.

http://www.mountain-forecast.com/ This site describes itself as a 'Dedicated mountain weather forecasts for more than 11200 (and growing) major summits for climbers and mountaineers, provided for up to 5 different elevations.'

I used it planning for a trip to the High atlas mountains in Morocco to find out how cold it would be at night at different altitudes.