Severe Storm Infrasound Observations during Spring 2018

Infrasound, sound at frequencies below human hearing, from severe storms has been associated with reports of severe weather events. Due to weak atmospheric attenuation, infrasound can be detected 100 km from its source and has been observed from tornado-producing storms well before tornadogenesis, which makes it an appealing method for long-range passive monitoring to improve tornado forecasting. However, the infrasound signature observed during tornadoes has a similar structure to that of some non-tornadic hail-producing storms. Studies of severe hail-producing storms with no evidence of concentrated vorticity have shown no acoustic energy. Recent simulations suggest that tornado-like vortices produce infrasound from near the melting level, where diabatic processes involving hail are active, suggesting that hail may have a connection with tornado infrasound. A station was established at Oklahoma State University to monitor atmospheric infrasound during severe storms that produce tornadoes and/or hail. Recent observations during the spring of 2018 along with available radar data will be presented and compared with observations from the same station during a small tornado on 11 May 2017.