OCR Event Manager - Master Calendar

Taking the Top-Down Approach: Relating Thunderstorm Overshooting Tops to their Updrafts and Environments

Thunderstorm overshooting tops (OTs) are manifestations of deep convective updrafts that extend past the tropopause, often into the stratosphere. OTs can transport moisture and aerosols into the stratosphere and have been connected to the occurrence and intensity of hazardous severe weather, such as tornadoes and hail. Much remains to be discovered, however, about how OTs relate to the updrafts that form them and the environments in which those storms form. Using observational data from the RELAMPAGO field campaign, Berman et al. (2024) found that overshooting top area (OTA) and duration (OTT) are not related to tropospheric or stratospheric thermodynamic profiles. Overshooting top depth (OTD), however, shows sensitivity to changes in both tropospheric and stratospheric thermodynamics.

Leveraging the observational results of Berman et al. (2024), Berman et al. (2025) used an ensemble of supercell numerical simulations to test the response of OTs to both thermodynamic and kinematic environmental modifications. Consistent with our observational work, these simulations show that OTD depends significantly on stratospheric static stability. In contrast, OTA tends to be relatively insensitive to stratospheric static stability and is more closely related to tropospheric updraft core area, which in turn depends on tropospheric vertical wind shear. Further questions remain, however, on what drives updraft intensity aloft in storms with ongoing OTs. Numerical simulations are being leveraged to understand updraft forcings above the mid-troposphere using Eulerian analyses of buoyantly and/or dynamically driven pressure perturbations. Results indicate that changes to non-linear dynamic pressure perturbations and buoyant vertical pressure perturbations are sensitive to the amount of curvature in the lowest 2 km of the wind profile. These changes cause the mid-to-upper tropospheric (8-12 km) vertical velocity to decrease with increasing curvature, yielding lower OTD.

OTA being well related to environmental kinematics and not correlated to stratospheric thermodynamics has important applications. OTA could be leveraged for severe weather forecasting applications or better constraining mass transport via deep convection into the stratosphere. OTD, however, has applications limitations. Caution should be exercised when using OTD or brightness temperature to determine updraft core strength as stratospheric static stability can modify OTD without modifications to updraft core strength. Comparisons between supercells and quasi-linear convective systems (QLCS) will also be discussed.