Detection and Warnings of Severe Convection with Doppler Weather Radar

This paper presents classification of convective storms,subjective identification and warning techniques of severe convective events including large hail,tornadoes.strong wind gust,and heavy convective precipitation.Favorable environmental conditions for large hail are high value of CAPE between?10°C and?30°C,significant deep layer (0～6km)vertical wind shear,and moderate 0°C level height above the ground.The characteristics of large hail radar echo are the echo region with the reflectivity over 50 dBz extending vertically above the?20°C level,the Weak Echo Region(WER)under the Echo Overhang,the Bounded Weak Echo Region(BWER)within the Echo Overhang,strong storm top divergence,and the Three Body Scattering Spike(TBSS),etc.The strong 0～1km vertical wind shear and low LCL are two important conditions for F2 or greater tornado potential.The warning criteria for tornadoes are the identification of strong mesocyclone or TVS within a mesocyclone of any strength.Favorable conditions for downburst and damaging wind gust potential are the existence of relatively dry air layer within the mid-troposphere and relatively steep lapse rate of the environmental temperature.The warning criteria for downburst are the constant descending of reflectivity core,accompanied by the convergence above cloud base.The warning for the damaging wind gust produced by moving strong convective storms such as multicell storm,supercell storm or squall line are based on the identification of the bow echo and/or the MidAltitude Radial Convergence(MARC).The severity of convective precipitation depends on rainfall rate and duration.The rainfall rate can be estimated by examining the low level reflectivity,and the precipitation duration can be judged based on the radar echoes movement.Special attention should be paid to the convective storms of tropical precipitation type,which has the tendency to produce heavy rainfall during a short period.Efforts should also be done to identify the back propagated MCSs which are slow moving with high probability of producing heavy rainfall.