Hurricanes are extraordinarily complicated and chaotic atmospheric phenomena. A single weather model can't possibly hope to reproduce all of the features that make up a hurricane, including observations from throughout the storm. Instead, meteorologists use computer models to simulate Hurricane Earl or other storms in order to better understand how they work and what might happen if they encountered certain conditions.
Computer models help meteorologists understand different aspects of hurricanes by reproducing their past behavior and predicting what could happen in future storms if certain conditions remain unchanged. By examining this data, meteorologists can develop more accurate forecasts for where, when, and severity of future hurricanes.