The mesoscale convective weather analysis plays an important role in operational forecasting. Progresses have been made in both the mesoscale analysis technique and its operation since 2011, which have significantly promoted the development of severe weather forecasting in the National Meteorological Centre (NMC). The updated Mesoscale Analysis Technical Specification consists of two parts. The mesoscale convective weather environment analysis is presented in this paper while the contents of the mesoscale nowcasting analysis are to be introduced in another paper. Based on ingredient method, the analysis content of the specification was simplified and reconstructed; meanwhile the refinements and the manipulation of analyzing products were given fully consideration. Moreover, a new part of sounding analysis and the quantitative standards for convective parameters were added into the specification. In the aspect of supporting technology, the subjective analyzing toolbox for mesoscale convective weather (in MICAPS 3) was improved, and a product integration system, including data and graphic products of severe convective weather monitoring, subjective and objective mesoscale analysis, diagnostic products of convective parameters and so on, was developed and has been being used in NMC.