Rawinsonde data were collected before and during passage of a squall line in Oklahoma on 15 May 2009 during the Second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) Nine soundings were released within 3 h, allowing for unprecedented analysis of the squall line's internal structure and nearby environment Four soundings were released in the prestorm environment and they document the following features low level cooling associated with the reduction of solar isolation by a cirrus anvil, abrupt warming (1 5 K in 30 min) above the boundary layer, which is probably attributable to a gravity wave increases in both low level and deep-layer vertical wind shear within 100 km of the squall line and evidence of ascent extending at least 75 km ahead of the squall line The next sounding was released similar to 5 km ahead of the squall line's Rust front, it documented a moist absolutely unstable layer within a 2 km-deep layer of ascent, with vertical air velocity of approximately 6 m s(-1) Another sounding was released after the gust front passed but before precipitation began, this sounding showed the cold pool to be similar to 4 km deep, with a cold pool intensity C approximate to 35 m s(-1) even though this sounding was located only 8 km behind the surface gust front The final three soundings were released in the trailing stratiform region of the squall line, and they showed typical features such as "onion -shaped soundings nearly uniform equivalent potential temperature over a deep layer and an elevated rear inflow jet The cold pool was 47 km deep in the trailing stratiform region, and extended similar to 1 km above the melting level, suggesting that sublimation was a contributor to cold pool development A mesoscale analysis of the sounding data shows an upshear tilt to the squall line, which is consistent with the cold pool intensity C being much larger than a measure of environmental vertical wind shear Delta U This dataset should be useful for evaluating cloud scale numerical model simulations and analytic theory but the authors argue that additional observations of this type should be collected in future field projects
