May 21 - July 30
Evolution of Dual-Pol Radar Signatures of QLCS Tornado Development
Olivia McCauley, Charles Kuster, Vivek Mahale, and Terry Schuur
What is already known:
- Within some QLCS systems exist areas of enhanced rotation called mesovortices which have the potential to produce tornadoes.
- QLCS tornadoes pose forecast challenges in terms of their rapid development within a highly dynamic environment as well as their short lifespan.
- Not all QLCS mesovortices produce tornadoes.
- Certain precursor radar signatures may yield insight into which mesovortices have a higher likelihood of producing tornadoes
What this study adds:
- An event by event radar signature breakdown of 18 tornadic mesovortices and 5 non-tornadic mesovortices
- Evidence that there may be correlations between certain precursor radar signatures in tornadic mesovortices.
- Evidence that there may also be correlations between certain radar signatures and non-tornadic mesovortices.
- Analysis of the most useful precursor radar signatures which includes ZDR Columns, enhanced areas of KDP around developing mesovortices, updraft/downdraft convergence zones along the leading edge of QLCSs, and concentrated areas of enhanced spectrum width at the low-levels.
Abstract:
The purpose of this study is to identify and analyze potential radar base and dual-polarization precursor signatures for quasi-linear convective system (QLCS) tornadoes. QLCS tornadoes present many forecasting challenges based on their rapid development, transience, and dynamic environment. QLCS tornadoes can form in between radar scans so it is imperative to forecasters to locate potential key radar signatures to issue tornado warnings in advance of tornadogenesis. Having the ability to detect early radar signatures of QLCS tornado development can potentially increase tornado warning lead time to the public and help those in danger better prepare for the risks tornadoes pose. Radar analysis was conducted using the Warning Decision Support System (WDSS). Base products used were spectrum width, reflectivity, and velocity; dual-pol products used were correlation coefficient, differential reflectivity (ZDR), and specific differential phase (KDP). There were a total of 18 tornadic mesovortices and 5 non-tornadic mesovortices studied. The analysis showed that the most beneficial radar precursor signatures may be ZDR columns, enhanced areas of KDP around developing mesovortices, updraft/downdraft convergence zones along the leading edges of QLCSs, as well as concentrated areas of enhanced spectrum width at the low levels.