WXSim works by importing data from available metars etc and if you have WD then it imports WD data as well. This data always needs to be imported for every different forecasting period as it is dynamic. I guess you mean can you leave it to pump out forecasts with no manual intervention, well the answer to that is no, you need to import fresh data and then run it yourself for each forecast. This is mainly because there are so many variable and teaks you may need to add to get a valid forecast.
Stuart