This tornado occurred on the Tippecanoe-Carroll County line in Indiana on 26 June, 2021, just after 0000 UTC. We compared data from the X-band Teaching and Research Radar (XTRRA), located near Purdue’s campus in West Lafayette, Indiana, to that of the NWS Indianapolis WSR-88D (KIND) which is used for warning issuance across central Indiana. The Warning Decision Support System Integrated Information (WDSS-II) system from the National Severe Storms Lab (NSSL) was used to derive azimuthal shear fields from both radars. In the supercell’s hook echo, KIND detected lower peak azimuthal shear (0.019 s-1) than XTRRA (0.028 s-1) did. This difference is due in large part to the relative beam heights of the two radars in the storm. The 0.5° beam of KIND, which was 88 km away, was sensing the storm approximately 1.3 km above ground level. In contrast, XTRRA’s 0.5° beam height at the storm range (16 km) was 170 m AGL. Therefore, KIND largely missed the near-surface rotation, where XTRRA, located much closer to the storm, picked up the azimuthal shear gradient very well. This case of a negative lead time tornado warning demonstrates the usefulness of supplemental radar coverage to help provide additional, high quality data that could potentially enhance the warning decision process.

