WSR-88D close-range sampling of neighboring supercells: a case of tornadic versus non-tornadic tendencies

Two supercell thunderstorms were sampled at close range on 16 April 2009 by the Lubbock, TX WSR-88D (KLBB). These two supercells, which occurred simultaneously and within 25 km of each other, evolved to present very different threats. One storm showed classic near-range tornado precursor signatures and subsequently became tornadic producing a series of weak tornadoes. Meanwhile, the second storm failed to display similar low-level rotational characteristics despite favorable reflectivity structure, and instead went on to produce giant (6.35 cm) hail resulting in more than $40M property damage in the city of Lubbock. This study compares and contrasts storm scale features identified at close range to the Doppler radar, including those operationally useful in discriminating the overall tornado threat. In addition, a detailed analysis of West Texas Mesonet data is used to describe how the presence of a low-level boundary may have been the determining environmental factor in each storm's evolution.