Observations Analysis and Hail Forming Area Identification on a Supercell Hailstorm

A detailed analysis on evolution of stream field and echo structure of a supercell hailstorm occurred on April 17th， 2011 is made based on the Doppler radar data, combining with radio sounding and surface observation. The main results are as follows: The hail storm occurs in the conditional instability and significant vertical wind shear environment, which belong to right moving storm. In the development stage, on the cross section shows that an organized updraft was formed gradually, and it promoted the formation and development of hail cloud. In hail forming stage, there's a strong tilted updraft and deep mesocyclone in the hail storm, and the main updraft corresponds to the weak echo region. The hailstorm maintained the typical BWER -overhang -Echo Wall echo structure..According to the evolution of "Zero line”, which correct with radar radial velocity and speed of hailstorm,it went towards to the overhang echo zone with hail cloud development, and crossed the overhang echo.The trend of "zero line" is upturned, and the collection power of “cave channel” near the "zero line" is so strong that is benefit to form hail. The location area where hail is formed can be analyzed through the "zero line" determine. A method of identify characteristic structure hail forming region is presented. According to the strong echo dislocation of high and low levels, the characteristic structure can be found quickly and accurately from the strong echo center section at two heights, and 45dBZ region at 6km height above 0 ℃ layer can be identified as hail formed region, where potential of hail can be calculated to 100%,and there is a good identification effect of hail formed region ,which contrast to the actual hail.