Environmental conditions of continual rainstorm caused by northeast cold vortex

From three elements of deep convective development,i.e.strong enough wet layer,stratification instability and strong enough trigger mechanism,the environment conditions of a continual rainstorm caused by northeast cold vortex from 11 to 15 in April 2002 was analyzed.It could be concluded that warm and wet conditions played an important role to the severe convective forecast of cold vortex,and strong cold vortex could seldom bring severe convective weather for the cold stratification profundity.However,subsidiary vortex divided from cold vortex and weak cold vortex related to warm and wet conditions in low layer could often bring abrupt severe convective weather.Baroclinic instability and vertical motion caused by strong wind vertical shear were the important conditions to severe convective trigger and maintenance.Wind direction veered 90 degree with altitude from boundary layer to 500 hPa before the storm occurred.With the development of convective weather,the wind vertical shear over 850 hPa gradually decreased,while the wind vertical shear under 850 hPa gradually increased because of the impact of the middle and high pressure caused by low layer cold stack.The severe convective weather caused by northeast cold vortex often lay in the left of upper jet exit.But the divergence field must be considered in real forecasting operation.