The increase in moisture due to land-atmosphere interactions influenced several critical parameters for severe thunderstorms. First, the increased moisture diminished the strength of the capping inversion. The combination of increased lift along the front, and the additional moisture were sufficient for convective development. In addition, instability in the atmosphere was dramatically increased. Modified soundings of the region approximately 150 km south of the frontal boundary consistently produced convective available potential energy (CAPE) values of approximately 3000 J/kg. However a similar modified sounding with surface data collected at the Benson Municipal Airport in the hour before the tornado resulted in CAPE values in excess of 7000 J/kg. Finally, the modified sounding using data from the Benson ASOS station yielded a lifted condensation level (LCL) and level of free convection (LFC) which were significantly lower than those soundings modified for the region 150 km south of Benson. The end result was a local atmosphere impacted by land-atmosphere interactions and an enhanced potential for violent, tornadic thunderstorms.
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