I use weather.co.uk -- gives 10-day forecasts, though obviously it doesn't usually turn out exactly as forecast. Amusing sometimes to compare & contrast with the 5-day forecasts on bbc.co.uk/weather
I like www.onlineweather.com. Choose data centre,then forecast charts,I am a sad person who prints the synoptic, then sees what we actually get by comparison. Think the site is quite good.
This site has loads of stuff including 120 hour surface pressure charts from the Met Office and 144 hour surface pressure/precipitation charts from the FNMOC