Comparing Downburst and Tornado Signatures in Mesoscale Convective Systems between NEXRAD and Phased Array Radar

Dual-polarization (dual-pol) phased array radar (PAR) is being considered as a potential replacement to
the current Weather Surveillance Radar-1988 Doppler (WSR-88D) network (NEXRAD) because of its high
cost-benefits, better polarimetric data quality, and finer temporal resolution. Research on the utility of using
dual-pol PAR to identify downburst signatures in mesoscale convective systems (MCSs) is limited; therefore,
this study uses KTLX and KOUN NEXRAD radars and the National Severe Storms Laboratory’s (NSSL’s)
Advanced Technology Demonstrator (ATD) S-band dual-pol PAR to compare temporal evolutions of specific
differential phase (K_DP) core maxima in seven cores. Sampled K_DP cores are obtained from three MCSs; a
warm season mesoscale convective complex (MCC) transition into a bow echo, a warm season bow echo,
and a cold season quasi-linear convective system (QLCS). The QLCS case provided mesovortices for further
analysis, in which this study uses quantifications of downdraft and circulation strength with ATD to identify
correlations between storm characteristics. This analysis revealed that: 1) the K_DP genesis threshold was met
earlier in ATD in all cases where it was measured; 2) K_DP and mesovortex sampling is incomplete with WSR-
88D and sometimes misses transient K_DP cores; 3) one downburst indicated by a K_DP core and subsequent
collapse augmented mesovortexgenesis in a cold-season QLCS case. These results support the conclusion
that PAR enables the earlier detection of downburst precursor signatures and illuminates details of K_DP cores,
collapses, and columns not captured by the current WSR-88D network.