This study investigates the effects of the Tibetan snow in spring on the subsequent East Asia summer monsoon circulation and rainfall. To this end, two types of sensitivity experiments on the Tibetan snow are performed with the National Centers for Environmental Prediction (NCEP) global and regional spectral models. First, to investigate the dynamical effects of the Tibet snow on the East Asia summer monsoon, 10-yr global simulation from 1996 to 2005 is performed with 5 member ensembles. Second, to assess the regional response, two sets of regional experiments are run, one for heavy snow and the other for light snow over the Tibetan Plateau during 2004 summer. Analyses of large-scale circulation over East Asia from the global simulation and a comparison of sensitivity experiments with external forcings will be investigated in more detail.