Tuesday, 29 August 2023
Boundary Waters (Hyatt Regency Minneapolis)
QLCS tornadoes account for more than a fifth of all tornado reports in the US, though there is a dearth of observational studies of these phenomena and their parent mesovortices. Apart from spawning tornadoes, QLCS mesovortices can contribute to the enhancement of severe straight-line winds. Many numerical modeling studies have considered the factors influencing the genesis and evolution of QLCS mesovortices, though until recently (i.e., PERiLS), observational analyses of these phenomena have generally been limited to short time periods.
On 30 April 2017, during the VORTEX-SE field campaign, the NOAA P-3 airborne Tail Doppler Radars (TDRs) sampled an extensive QLCS as it progressed through Alabama, with complementary observations gathered from the NWS Hytop, AL WSR-88D (KHTX), and a University of Oklahoma Shared Mobile Atmospheric Research and Teaching Radar (SMART-R 2). This QLCS was responsible for numerous high wind reports resulting in one fatality and produced damaging straight line winds – originally assessed as EF-0 tornado damage – near Cullman, AL. Airborne and ground-based radar observations spanning nearly 2.5 hours have been incorporated into three-dimensional wind syntheses, revealing numerous mesovortices of various scales, one of which persisted through much of the analysis period.
Potential mechanisms responsible for the formation and maintenance of QLCS mesovortices include tilting and stretching of baroclinically generated horizontal vorticity, and the release of horizontal shear instability (HSI). This study seeks to provide observational evidence to elucidate the relative contributions of these mechanisms in the lifecycles of the 30 April 2017 mesovortices. Three dimensional winds and reflectivity will be presented along with atmospheric soundings and in situ surface observations to provide a sense of the kinematics at play and the associated influence on/by the near-surface environment.
On 30 April 2017, during the VORTEX-SE field campaign, the NOAA P-3 airborne Tail Doppler Radars (TDRs) sampled an extensive QLCS as it progressed through Alabama, with complementary observations gathered from the NWS Hytop, AL WSR-88D (KHTX), and a University of Oklahoma Shared Mobile Atmospheric Research and Teaching Radar (SMART-R 2). This QLCS was responsible for numerous high wind reports resulting in one fatality and produced damaging straight line winds – originally assessed as EF-0 tornado damage – near Cullman, AL. Airborne and ground-based radar observations spanning nearly 2.5 hours have been incorporated into three-dimensional wind syntheses, revealing numerous mesovortices of various scales, one of which persisted through much of the analysis period.
Potential mechanisms responsible for the formation and maintenance of QLCS mesovortices include tilting and stretching of baroclinically generated horizontal vorticity, and the release of horizontal shear instability (HSI). This study seeks to provide observational evidence to elucidate the relative contributions of these mechanisms in the lifecycles of the 30 April 2017 mesovortices. Three dimensional winds and reflectivity will be presented along with atmospheric soundings and in situ surface observations to provide a sense of the kinematics at play and the associated influence on/by the near-surface environment.
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