Abstract:

Based on the data from the Himawari-8 satellite, Doppler weather radar, regional automatic and conventional meteorological stations, and ERA-Interim (European Centre for Medium-range Weather Forecasts Interim) reanalysis, the environmental condition, triggering mechanism and evolution of MCS (Mesoscale Convective System) of a large-scale strong storm occurred in He'nan province on June 5, 2016, were analyzed.It shows that under the background of a North China cold vortex, the cold advection at the high level, combined with the development of warm ridge and the surge of the CAPE (Convective Available Potential Energy) values, provides unstable conditions for the development of the MCS.The convergence line at the surface and cold pool is the trigger mechanism.Southwest He'nan province is located in the high-energy area, where air masses with different temperatures and humidity properties meet each other.The intrusion of cold air in the middle and high level and the adiabatic lapse rate of the dry air below the middle level provide the possibility for the hail weather.Central and southern He'nan province is located in the area having a large amount of PW (Precipitable Water), and the deep wet layer and low uplift condensation height are conductive to the production of severe precipitation.The suction of the divergence at the high level and convergence at the low level leads to a strong upward movement over the Southwest He'nan province.The dynamic uplift is enhanced by the variable pressure wind generated by the thunderstorm high pressure.The strong convection echo is developed by the small and medium scale dynamic convergence.Hail weather occurs in the area having large values of TBB (Black Body Temperature) gradient in front of MCSs, and heavy precipitation occurs near the low value center of TBB.The radar product analysis shows that the strong echo drape, TBSS (Three Body Scattering Spike) and the fast-moving bow echo, the gust front and rear inflow jet are good indicators for the early warning of hail and thunderstorm gale.The significant warming zone at 12:00 at 925 hPa, the high-value zone of CAPE and the intersection zone between the cold pool outflow and the warm air are the potential zones for the development of strong convection.The height of wet-bulb temperature with 0 ℃ is closely related to hail.

Key words: Mesoscale convective systerm (MCS), Trigger mechanism, Bow echo, Rear inflow jet, Cold pool