We mainly get data from where planes and weather balloons travel -- there's no way to get detailed data about the entire volume of the atmosphere (although it's

We mainly get data from where planes and weather balloons travel -- there's no way to get detailed data about the entire volume of the atmosphere (although it's being worked on.) As a result, models get initialized by the output of previous models, and the main thing that keeps them somewhat close to reality is the data we collect on the surface. Also, since a plane flight takes several hours, you really need a prediction to pick the correct path, not just the data right now. [3D satellite data for temperature and water vapor: https://en.wikipedia.org/wiki/GNSS_radio_occultation https://en.wikipedia.org/wiki/GNSS_radio_occultation but I don't think there's an equivalent for wind speed other than the very limited doppler radar.]