Future changes in the vertical structure of severe convective storm environments over the U.S. central Great Plains

Abstract

Abstract The effect of warming on severe convective storm potential is commonly explained in terms of changes in vertically-integrated (“bulk”) environmental parameters, such as CAPE and 0–6-km shear. However, such events are known to depend on details of the vertical structure of the thermodynamic and kinematic environment that can change independently of these bulk parameters. This work examines how warming may affect the complete vertical structure of these environments for fixed ranges of values of high CAPE and bulk shear, using data over the central Great Plains from two high-performing climate models (CNRM and MPI). To first order, projected changes in the vertical sounding structure is consistent between the two models: the environment warms approximately uniformly with height at constant relative humidity and the shear profile remains relatively constant. The boundary layer becomes slightly drier (−2–6% relative humidity) while the free troposphere becomes slightly moister (+1–3%), with a slight increase in moist static energy deficit aloft with stronger magnitude in CNRM. CNRM indicates enhanced low-level shear and storm-relative helicity associated with stronger hodograph curvature in the lowest 2 km, whereas MPI shows near zero change. Both models strongly underestimate shear below 1 km compared to ERA5, indicating large uncertainty in projecting subtle changes in the low-level flow structure in climate models. Evaluation of the net effect of these modest thermodynamic and kinematic changes on severe convective storm outcomes cannot be ascertained here but could be explored in simulation experiments.