Classic Cold Front

If you catch this early enough, you can see the line of clouds along the frontal boundary:
http://www.intellicast.com/National/Radar/Current.aspx

http://www.hpc.ncep.noaa.gov/noaa/noaa.gif

Other wx sites are good too. This is why I never rely on just one site.  I rotate around to get different views of the weather.  The European Weather sites are pretty accurate too.

Try this one for size:
http://www.metoffice.gov.uk/weather/europe/europeforecast.html

can you name some others?