A study of the environmental conditions and radar echo characteristics of the supercell-storms in northern Jiangsu

The environmental conditions and radar echo features of the 72 superccll-storms in northern Jiangsu Province arc in-vcstigated, based on the data from 5 Doppler weather radars,3 radiosonde stations, and surface weather stations during the 2005-2009. The sounding analyses indicate that high precipitation supercells usually occur with very high CAPE, medium deep layer(0-6 km) vertical wind shear, and high value of low level dewpoint, while classic suppercells occur with high CAPE, strong deep layer vertical wind shear, and moderate low level dewpoint. Supercells producing large hailstones and/or strong wind gust occur in the environment with lower height of 0℃ and 20℃ levels, relatively sharp lapse rate of temperature, strong deep layer vertical wind shear, and moderate surface dewpoints. However, the tornadic supercells occur in the environment with strong lower level (0-1 km) vertical wind shear, lower LCL, less lapse rate of temperature, and high surface dew-points, frequently accompanied by flash heavy rain. The results of Doppler weather radar echoes analysis shows that there are three types of supercell storms in northern Jiangsu:classical supcrcells, high precipitation supercells, and high precipitation supercell complexes. A classical supercell is usually isolated, with a mesocyclone at rear-right flank(relative to storm moving dircetion), a hook echo at low level, and a high reflectivity core above a broad bounded weak echo region(BWER).A high pre-cipitation supcrcell has a front inflow notch with a mesocyclone, a wide bow-shaped echo next to the inflow notch at low level, and a BWER or WER, with the mesocyclone circulations filled with precipitation. high precipitation superccll complexes have a similar structure to the high precipitation, but with longer life time. The storm cell characteristics analysis displays that, in majority of cases, the strongest echoes of the supercells range from 55 dBz to 76 dBz, the vertical integrated liquid(VIL) from 35 kg/m2 to 90 kg/m2, the rotation speed of m esocyclones is greater 15 m/s, and the duration over 40 minutes. High probability of tornados can be expected when a mesocyclone possesses very low base and smaller diameter.