There are number of different ways to access the NWS data and graphs - not surprisingly it is hard to discover them! They do have an XML web service for daily

There are number of different ways to access the NWS data and graphs - not surprisingly it is hard to discover them! They do have an XML web service for daily and hourly forecasts http://graphical.weather.gov/xml/ http://graphical.weather.gov/xml/ but you can also download binary files that contain all the same weather elements for the US. I'm actually close to completing a python library that will be open source and provide an easy way to access the NWS national digital forecast database.