 As proposed by Edward Lorenz in 1963 , it is impossible for long @-@ range forecasts — those made more than two weeks in advance — to predict the state of the atmosphere with any degree of skill , owing to the chaotic nature of the fluid dynamics equations involved . Extremely small errors in temperature , winds , or other initial inputs given to numerical models will amplify and double every five days . Furthermore , existing observation networks have limited spatial and temporal resolution ( for example , over large bodies of water such as the Pacific Ocean ) , which introduces uncertainty into the true initial state of the atmosphere . While a set of equations , known as the Liouville equations , exists to determine the initial uncertainty in the model initialization , the equations are too complex to run in real @-@ time , even with the use of supercomputers . These uncertainties limit forecast model accuracy to about six days into the future . 
