 In September 1954 , Carl @-@ Gustav Rossby assembled an international group of meteorologists in Stockholm and produced the first operational forecast ( i.e. routine predictions for practical use ) based on the barotropic equation . Operational numerical weather prediction in the United States began in 1955 under the Joint Numerical Weather Prediction Unit ( JNWPU ) , a joint project by the U.S. Air Force , Navy , and Weather Bureau . The JNWPU model was originally a three @-@ layer barotropic model , also developed by Charney . It only modeled the atmosphere in the Northern Hemisphere . In 1956 , the JNWPU switched to a two @-@ layer thermotropic model developed by Thompson and Gates . The main assumption made by the thermotropic model is that while the magnitude of the thermal wind may change , its direction does not change with respect to height , and thus the <unk> in the atmosphere can be simulated using the 500 mb ( 15 inHg ) and 1 @,@ 000 mb ( 30 inHg ) geopotential height surfaces and the average thermal wind between them . However , due to the low skill showed by the thermotropic model , the JNWPU reverted to the single @-@ layer barotropic model in 1958 . The Japanese Meteorological Agency became the third organization to initiate operational numerical weather prediction in 1959 . The first real @-@ time forecasts made by Australia 's Bureau of Meteorology in 1969 for portions of the Southern Hemisphere were also based on the single @-@ layer barotropic model . 
