High-Shear, Low-CAPE environments: What we know and where to go next

Though increasingly acknowledged as a unique forecasting challenge, environments characterized by marginal instability and large magnitudes of bulk wind shear [hereafter referred to as High-Shear, Low-CAPE (HSLC) environments] remain poorly understood and scarcely researched. Limited largely to the last two decades, research on HSLC environments has been primarily based on spatial and temporal climatologies and operational case studies, the latter of which particularly focus on radar signatures commonly identified in severe HSLC convection. Only a handful of modeling studies have included marginally unstable cases with CAPE values ≤ 500 J/kg. Thus, while recent research has led to improvements in forecasting and nowcasting the severe potential in HSLC environments, our knowledge regarding the dynamics inherent to severe HSLC convection is relatively limited compared to that of high CAPE convection.

Despite advancements in operational techniques, HSLC environments are still considered somewhat of an enigma due to their commonality (particularly in the cool season and overnight) but overall disproportionately small number of severe events. However, recent climatologies of HSLC severe convection reveal that HSLC environments are capable of producing the entire spectrum of severe hazards, including significant tornadoes, straight-line winds, and hail. This presentation aims to provide a review of the current knowledge of HSLC environments and their potential of supporting severe convection while exploring how the missing pieces can be addressed with ongoing and future research.