Numerical Analysis of a Squall Line Hail Process on Weak Precipitation Circulation in Northwest Henan Province
Niu Guangshan
Abstract：Northwest of Henan appeared hail,squall line and strong wind severe weather at the night of May 6,2015.We performed numerical analysis of this hail squall line process under the background of weak precipitation circulation by using conventional observation data,NCEP reanalyzed (1° × 1°) data and Zhengzhou doppler radar data.The results showed:general synoptic scale circulation situation is not conducive to the anticipation of the hail squall line process,by means of mesoscale analysis and fenced area drop zone method could forecast the hail squall line better.The CAPE energy field on northwest of Henan was comparatively weak,unstable energy and water vapor condition were not conducive to heavy rain,but because of the invasion of cold advection and continued accumulation of instability energy of high temperature and humidity,cold front intrusion and greater vertical wind shear,there were convection triggering mechanism over northwest Henan.The vertical layer structure of low-level convergence and upper-level divergence along with deepening vertical upward motion made the strong convection strengthening and maintaining,resulted in the formation of hail and squall lines.The height of-20 ℃ and 0 ℃ layers were suitable conducive to the hail on northwest of Henan.The V-notch,radar reflectivity characteristics,gust fronts and speed field distribution on north and south ends of squall line led to a better indicative significance for strong wind and hail forecast.
Keywords：hailsquall linemesoscale analysistriggering and maintenance mechanismcomposite reflectivitybase speed
Publication Date：2017-07-02
Online Publishing Date：2026-09-12(First online date of this platform, not the publication date of the document)
Pages：8( 38-45 )