NEW : Chanthu has slowed but is moving steadily closer to southern China . Comment: Tropical storm could deluge already soaked areas with 20 inches of rain . NEW : State Council calls situation `` grave '' NEW : Chinese news agency says more than 700 killed by floods this year .
NEW : Chanthu has slowed but is moving steadily closer to southern China . NEW : Tropical storm could deluge already soaked areas with 20 inches of rain . NEW : State Council calls situation `` grave '' NEW : Chinese news agency says more than 700 killed by floods this year .