Model Forecasts- Numerical Weather Prediction

• Predict the state of the atmosphere (e.g., pressure, temperature, precip, winds, etc) in time
• The atmosphere and atmospheric processes are represented by mathematical equations
• The equations are solved on supercomputers and are initialized with observational data
• Most all of the forecast models are run at NCEP
• models produce prognostic charts (progs) of the model output
• Q:  Why are the models often wrong????