In order to improve the ability to use the products of T639, a synoptic verification on its medium range forecasts in spring 2014 is made in comparison with the NWP of ECMWF and Japan models. The results show that all the three models have good performances on the aspect of predicting the larger scale circulation evolution and adjustment in Asian middle and high latitude areas and the evolution of southern branch trough. For the prediction of temperature at 850 hPa, ECMWF shows a better performance than the other two models. Taking the sandstorm process during the period of April 22-24, 2014 as a case, it is found that ECMWF is more effective than the other two models in medium range forecasts of strong surface wind causing the sandstorm weather process.