CumulusMX will run very well on a Raspberry PI. If you do not use a lot of peripherals, the power usage on the RPi will probably be in the range of 4-5 watts.
As I experimented with different ways of saving & viewing weather data from a VP2 & Meteobridge, I have run on a RPi2B:
- Apache
- CumulusMX,
- MySQL database
- Meteotemplate templates
- Weather34 templates
Both of these templates can scale the web pages for cell & tablet screens. The RPi with MySQL means that
you are responsible for your data - not WU / IBM or any other cloud service.