Thank you for this great explanation! I work in a non-technical capacity with a weather forecasting firm, and this explains some things I've not understood. Here's another question, which even Wikipedia and Google have been unable to answer (in a non-technical way): what is a "statistical dynamical model"? I often see these mentioned as a source of weather and climate forecasts. I can dimly imagine what this might be. An explanation or pointer to other sources would be helpful.