Tornado and Hail Infrasound Observations during Severe Storms

Storm systems, particularly those that produce tornadoes, are known to emit infrasound (sound at frequencies below human hearing). Infrasound has been observed up to 2 hours before tornadogenesis and can be detected from over 100 km away due to weak atmospheric attenuation. This suggests that passive infrasonic monitoring may be a useful tool for monitoring tornado occurence. However, similar infrasound signals have been observed with hail production. As a part of the Collaboration Leading Operational UAS Development for Meteorology and Atmospheric Physics (CLOUD-MAP) project, an infrasound monitoring station was established at Oklahoma State University. Tornadic and non-tornadic infrasound observations from this monitoring station will be presented. This includes a small EFU tornado on 11 May 2017 which occurred about 19 km from this station, in which case a coherent, concomitant signal was detected with characteristic tones originating from the direction of the supercell that produced the tornado. These results will be compared alongside radar data with a sampling of results from other hail producing, non-tornadic storms.