 The inaccuracy of forecasting is due to the chaotic nature of the atmosphere, the massive computational power required to solve the equations that describe the atmosphere, the error involved in measuring the initial conditions, and an incomplete understanding of atmospheric processes.Hence, forecasts become less accurate as the difference between current time and the time for which the forecast is being made (the "range" of the forecast) increases.The use of ensembles and model consensus help narrow the error and pick the most likely outcome.