 In 1922 , Lewis Fry Richardson published the first attempt at forecasting the weather numerically . Using a hydrostatic variation of Bjerknes 's primitive equations , Richardson produced by hand a 6 @-@ hour forecast for the state of the atmosphere over two points in central Europe , taking at least six weeks to do so . His forecast calculated that the change in surface pressure would be 145 millibars ( 4 @.@ 3 inHg ) , an unrealistic value incorrect by two orders of magnitude . The large error was caused by an imbalance in the pressure and wind velocity fields used as the initial conditions in his analysis . 
