Turbulence Characteristics of Severe Straight-line Winds in a Rear-Flank Downdraft and Bow Echo Observed by the Texas Tech Univ. Ka-Band Mobile Doppler Radars

Convective outflow is the dominant extreme wind type for much of the inland midlatitudes. Therefore, characterization of the turbulence properties of extreme straight-line winds in convective outflow is valuable for informing design standards for wind loading on structures.

Considerable prior research has focused on characterization of the turbulent properties of severe convective outflow from buoyantly driven downdrafts, such as microbursts. However, comparatively little research has examined the turbulence of straight-line winds within the rear-flank downdraft (RFD) of supercells and quasi-linear convective systems (QLCS), which generate more than half of the significantly severe damaging wind reports in the United States. The forcing mechanisms for damaging winds within the RFD and QLCSs are different than microbursts, which suggests that they may have different turbulence characteristics relevant to wind engineering.

This study examines observations of damaging straight-line winds collected by the Texas Tech University Ka-band (TTUKa) mobile Doppler radars in an RFD occurring near Dumas, TX on 18 May 2010 and within a bowing segment of a QLCS near Pep, TX on 5 June 2013. The turbulent properties of each event are assessed using eddy dissipation rates derived from the TTUKa spectrum width.