May 24 - July 30
Pre-Convective HSLC-Supercell Environmental Analysis from a Boundary-Layer Profiling Perspective
Dana K. Pawlowski, Elizabeth N. Smith, Tyler M. Bell, and Tyler J. Pardun
What is already known:
- High shear low CAPE (HSLC) environments forecasting challenges can be associated with rapid destabilization of the convective boundary layer (CBL).
- CBL destabilization typically occurs around 2-6 hours prior to storm passage.
- There are distinct variations of environmental influences in the boundary layer depending on convective modes.
What this study adds:
- In the discrete convection mode, the clear shift toward destabilization and convective state appears to occur approximately 3 hours prior to storm passage based on surface-based CAPE evolution.
- Out of possible contributors to destabilization, lapse-rate appears to have the most influence in destabilization for discrete storm modes–as expected–followed by near-surface dewpoints, and lastly near-surface temperatures.
- This discrete mode single case study broadly reflects and supports the hypothesized evolution and destabilization contributions put forth in prior longitudinal results.
Abstract:
Complex atmospheric environments in the southeastern United States cause obstacles in forecasting and awareness in severe weather prone locations. High-shear, low CAPE (HSLC) environments play a large role in complicating numerical weather prediction, operational forecasting, and warning processes. This can limit accuracy and further contribute to severe events in these regions becoming high impact events. One of the main explanations behind our lack of understanding about HSLC environments is due to the observation gap in the boundary layer. In efforts to address this gap, there have been developments of ground-based profiling platforms. Relevant data is reviewed from the mobile unit CLAMPS which provides high resolution profiles of temperature, moisture, and wind, similarly to radiosondes, but at much finer temporal scale. This case study analyzes the pre-convection environment before a discrete supercell passes over the unit to investigate the detailed environmental cues that lie within the boundary layer. This analysis also determined the amount of influence for each known factor in discrete mode convection, along with confirming previous results of another study regarding the rapid destabilization process thought to be important in the southeastern United States.