The influence of convection initiation strength on subsequent simulated supercell evolution

Recent studies have shown how very small differences in the background environment of a supercell can yield different outcomes, particularly in terms of tornado production. In this study, we use a novel convection initiation (CI) technique to simulate six supercells with a focus on their early development. Each experiment is identical except for the strength of thermal forcing for the initial convection initiation. Each experiment yields a mature supercell, but differences in storm-scale characteristics like updraft speed, cold pool temperature deficit, and vertical vorticity development abound. Of these, the time when the mid-level updraft strengthens is most strongly related to initiation strength, with stronger thermal forcing favoring quicker updraft development. The same is true for the low-level updraft, with the additional relationship that stronger thermal forcing also tends to yield stronger low-level updrafts for around the first 2 hrs of the simulations. The experiments with faster updraft development tend to be associated with more rapid surface vortex intensification; however, cold pool evolution differs between simulations with weaker vs. stronger thermal forcing. Stronger thermal forcing also yields deviant, rightward storm motion earlier in the supercell’s life cycle that remains more consistent for the duration of the simulation. These results highlight the range of supercellular outcomes that are possible across a background environment due to differences in storm-scale initiation strength. They are also of potential importance for predicting the paths and tornado potential of supercells in real time.