Analysis Of Severe Convective Weather Accompanied By Supercell Storms In Yichang

10severe convective storms with supercells in Yichang of2004-2009have been analyzed.The results show that the severe convective weathers that supercells mainly produced were strong winds、hail and rainstorms.Among them,strong winds with the highest wind probability of100%, followed by short-time strong precipitation and hail. The supercell storm occurs mainly in the environment with strongly unstable stratification and abundant low-level moisture conditions.Relatively, hail is likely occurred in shallow wet layer, and heavy precipitation is in deep wet layer. Severe convective weather are mainly triggered by synoptic scale systems.Before strong supercell storm occurred and rapid developped, convergence lines often appear in ground boundary layer. Moderate to strong Vertical wind shear in0-6km is conducive to the generation and development of supercells. The supercell storm always appears in the afternoon to night,and disappear in midnight to morning. Life history of a supercell storm is generally a few minutes to a few hours. The supercell storm characteristics of the top and bottom height is very difference,which the lowest is to0.5km, and the maximum to7.9km.The bottom of the supercell storm which caused more than8gale is very low,and which is rapid declining before the arrival of strong winds in2-4volume scans. The shear values are quite different,the highest is to Thousandths43per second.The higher the shear is,the bigger of the windy is,and the disasters of the wind is more. The low-level base reflectivity in the supercell storm easily appear hooked echo,bumps which toward to the direction of inflow,compact massive echo characteristics.The high, medium and low-level configuration of base reflectivity in the supercell storm which life history more than4scans behave same that there are overhanging echos on the middle and senior level above weak echos on the low level.The velocity characteristics of Supercell storm are different in diferent height. In the lower-level of the velocity product there are cyclonic convergence,and convergence increase gradually then turn to pure cycone in the medium level, sometimes cyclone and anti-cyclone appear at the same time,and turn to anti-cyclone with divergence in the high level.High top height of echo(ET) and high vertically integrated liquid water content (vil) often exist in the supercell storm. Generally speaking, the higher the top height of echo, the bigger the vertical integrated liquid water content, the stronger the weather will appear. Especially when hail appears, is largely corresponding to high top height of echo(ET) and high vertically integrated liquid water content (vil),and when the radio of vertically integrated liquid water content (VIL) to the top height of echo (ET)which called VIL density is greater than3.5g·m-3, the possibility of appear large hail with large diameter more than2cm is very high.