Role of the interaction between a gust front and a mesoscale air mass boundary in convection initiation: a case study

The local convection initiation (CI) mechanisms of a convective case that occurred on 5 August 2017 in Cangzhou, northern China, were studied using Doppler radar and automatic weather station observational analysis, along with Variational Doppler Radar Analysis System assimilation analysis. During the convective process, a gust front appeared ahead of two existing convective systems, respectively. In the warm and moist environment ahead of the gust fronts in the south, there was a mesoscale air mass boundary. With the process of a gust front moving southward, approaching the mesoscale air mass boundary, the convergence intensified in the area between the gust front and the mesoscale air mass boundary. Finally, the strong convergent updraft exceeded the level of free convection and triggered the new convection.