It has a second program called wxsimate which downloads METAR, SYNOP, Buoy, GFS, RAOB and Ozone data from the net relative to your location and without this stuff it really cannot do much at all, the WD data is really fine tuning stuff. All this other data gives all sorts of meteorological data which it needs in order to do a proper forecast, most of this data is obtained from servers in the USA as places like our UK Met Office charge huge bucks for the same data but in the USA it is free :roll: 
#-o
Stuart