In this study, rapidly intensifying (RI) tropical cyclones (TCs) with ‘Atypical’ convection in the Northwest Pacific were screened by using reanalysis data and infrared cloud images. A group of slow-intensifying (noRI) typhoons with ‘Typical’ convection were gathered for comparison. It is found that the RI group has a stronger maximum region of surface latent heat flux on the left side of the vertical wind shear (VWS) direction. To further explore possible mechanisms, the ‘Atypical’ convection case ‘Lekima’ (2019) was selected for sensitivity numerical experiments. The diagnostic results indicate that the surface latent heat flux on the left side of the VWS direction helps establish convective-instability in the region. Consequently, the effect of the "Ventilation effect" was weaken through the "Boundary layer entropy recovery" mechanism caused by the surface latent heat flux. Under easterly VWS, convection activity can be enhanced in high surface latent heat flux regions during the transition from the down-shear to the up-shear, thereby stimulating strong upper outflow channels. The establishment of outflow channels (Outflow blocking mechanism) can resist the environmental easterly flow, which weakening the strength of VWS, and allowing the typhoon to develop vertically.