 This guidance is presented in coded numerical form, and can be obtained for nearly all National Weather Service reporting stations in the United States.As proposed by Edward Lorenz in 1963, long range forecasts, those made at a range of two weeks or more, are impossible to definitively predict the state of the atmosphere, owing to the chaotic nature of the fluid dynamics equations involved.In numerical models, extremely small errors in initial values double roughly every five days for variables such as temperature and wind velocity.