By using the 0.5°×0.5° GFS and conventional observational data, a Meiyu heavy rain took place from 5 to 7 in July 2013 over the northeastern Hubei Province is analyzed.The results show: (1) The rainfall has obvious diurnal variations: increased at night and decreased in the day time; the convergence at low levels had the same tendency with that of the rainfall.(2) Positive divergence variability at upper levels and negative divergence variability at middle and low levels were favorable to rainfall increase. These changes were ahead of the heavy rainfall. Negative divergence variability at low levels began in the evening, which was helpful to the convergence increase at low levels at night.(3) By the divergence equation with twoitem combination, it is found that although the deviation of the nonlinear balance equation is the main item of divergence variability, the remainder is the only item whose value became obviously negative in the beginning stage of the heavy rain. (4) By the divergence equation with fouritem combination, it is found that the convergence in the boundary layer was one of the rain trigger factor; the ageostrophic equilibrium item with large positive value in the near surface indicated the weakening of the rain well; and item in connection with upward motion had large negative values at the middle levels in the peak rain stage.