Thermodynamic and Kinematic Observations within Severe Convective Storm Updrafts

Little is known about thermodynamic and kinematic properties inside severe convective storm updrafts owing to difficulties obtaining in situ observations. Instead, we rely on vertical motion information from multi-Doppler analyses (which can have large errors) and make assumptions about thermodynamic conditions (e.g., adiabatic ascent). 

Recently we have sampled conditions within severe storm updrafts with Sparv Embedded Windsonds. During the 2024 Insurance Institute for Business and Home Safety (IBHS) field deployment and the 2025 U.S. National Science Foundation-funded “In-situ Collaborative Experiment for the Collection of Hail In the Plains” (ICECHIP) field project, we deployed numerous Windsonds into severe storm inflow regions and obtained observations within the storms’ updrafts. This allows for exploration of how updraft thermodynamic and ascent profiles vary between storms and within the lifetime of individual storms. In preparation for ICECHIP, testing Windsonds in controlled conditions revealed sensor biases and necessitated special modifications to accurately measure in-storm conditions. Based on these tests, Windsonds were modified to protect temperature and relative humidity sensors from precipitation, allowing measurements within the updraft. Modified sensors were used during ICECHIP.

As an example, during ICECHIP IOP12 on 6 June 2025 near Ropesville, Texas, five supercell updraft profiles were obtained using Windsonds over a 2-hour period beginning early in the storm’s lifecycle. Vertical profiles of in-updraft potential temperature, virtual potential temperature, equivalent potential temperature, and saturation equivalent potential temperature between 3-6 km above ground level (AGL) were surprisingly similar over the 2-hr period. Similarly, within the 0-2.5 km AGL inflow layer, thermodynamic and kinematic profiles were similar, except for the final sonde, which was released within the storm outflow. Despite being released in the outflow, however, that sonde successfully entered the updraft and attained a peak ascent rate of 38 m s^-1. The maximum ascent rate within the storm as measured by the five sondes ranged from 25–54 m s^-1. Interestingly, the magnitude of the vertical motion early in the supercell’s lifecycle (45 m s^-1) was of a similar magnitude to the vertical velocity within the mature storm (44 m s^-1) 75 minutes later, despite vastly different radar presentations and hail production.

We will discuss variability of updraft thermodynamic and kinematic profiles across different storms, and throughout individual storms’ lifetimes, as well as surprising similarities among different storms (including increases in equivalent potential temperature within the hail growth zone).