Application of VIL and VIL Density in Warning Criteria for Hailstorm

Using the Jinan-CINRAD/SA data in 2002-2005,the distributive characteristics of Grid Vertically Integrated Liquid(VIL),the VIL Density(VILD) and the VIL above the 0℃ layer(VILH) in the cases of convective cloud are analyzed.It is pointed out that the difference of VIL,VILD and VILH are obvious,the hail shooting had significantly higher grid VIL,VILD and VILH values on the average,through the entire time series when compared to the non-hailstorms.The maximum average values of Grid VIL,VILD and VILH of hailstorms is higher than the non-hail shooting,they are 20 kg·m-2,1.7 g·m-3and 16 kg·m-2 respectively.Grid VIL values for hail shooting have obvious phenomenon of increasing abruptly in the late stage of storm developing,such as the increasing magnitude was 15.4 kg·m-2 for severe hail shooting.The hail shooting almost began after the VIL peak,so VIL peak used as a severe weather predictor has limited lead time.The average lead time was decided by the amount of time from the VIL increasing abruptly VCP end to the VIL peak VCP end.The average lead time in May,June and July was 4.8,11.4 and 12.3 minutes,respectively.TS,PO and FAR were calculated for some parameters to determine the best possible points for which a warning or no warning decision can be based.The VIL,VILD and VILH thresholds in different months were examined for usable signals as warning hails.The VILH thresholds in May,the VILD thresholds in June,and the VIL thresholds in July have the best effect on warning hails.