Like all other weather models available, it relies on a weather input file which can be comparable to a photographic "snapshot" of the earth's atmosphere. If these inputs are inaccurate, the model forecast is likely to be inaccurate. Fortunately we provide you with two forecasts twice daily created by independently generated weather input files. If there is a discrepancy between the model forecast and real time observations of more than 30 degrees and/or 5 knots the forecast should be discarded. This will happen in approximately 15% of cases.