On Counter-Rotating Vortices at the Rear or Left Flanks of Developing Supercells
Abstract
Kramar et al. (2005, MWR), using close-range mobile (non-Doppler) radar data and highly idealized numerical simulations, described and explained the formation of a radar signature sometimes observed in developing supercells, which they named the "Owl Horn" echo, owing to its similarity in appearance to the Great Horned Owl. They found that the tilting of baroclinically produced horizontal vorticity at the rear of a developing storm is responsible for counterrotating vortices that are associated with the hook echoes that characterize the radar-echo appearance. Since then, our group has documented more examples of this signature, but with rapid-scan, X-band, polarimetric, mobile Doppler radar (RaXPol) data. We have also documented counter-rotating vortices of the opposite sense, which may be associated with the traditional cyclonic-anticyclonic couplet produced at the edges of updrafts in growing cumulus towers, but to the best of our knowledge never linked to hook-like radar reflectivity signatures. Both of these vortex couplets were located at midlevels.
In this presentation I will show some more detailed examples of this feature in (1) a developing tornadic supercell in southern Kansas on 14 May 2018 and (2) a developing non-tornadic supercell in southern Oklahoma on 21 April 2017. We will contrast vortices associated with an "Owl Horn" echo to the vortices long ago documented by Lemon (1976, MWR), which he referred to as "wake vortices." The vortices associated with the "Owl Horn" echo are important because (1) they could trigger unnecessary tornado warnings and (2) they may be used as an early predictor that a convective storm will soon develop into a supercell. The main goal of this talk is to make the community aware of the rich variety of vortices that are found in severe convective storms, some not yet widely recognized perhaps because they occur early in the life of the storm and do not appear to be necessarily associated with tornadoes.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A53U3049B
- Keywords:
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- 3314 Convective processes;
- ATMOSPHERIC PROCESSES;
- 3329 Mesoscale meteorology;
- ATMOSPHERIC PROCESSES;
- 3354 Precipitation;
- ATMOSPHERIC PROCESSES;
- 4313 Extreme events;
- NATURAL HAZARDS