| Summary: | A multi-radar analysis of the 20 May 2013 Moore, Oklahoma, U.S. supercell is presented using three Weather Surveillance Radars 1988 Doppler (WSR-88Ds) and PX-1000, a rapid-scan, polarimetric, X-band radar, with a focus on the period between 1930 and 2008 UTC, encompassing supercell maturation through rapid tornado intensification. Owing to the 20-s temporal resolution of PX-1000, a detailed radar analysis of the hook echo is performed on (1) the microphysical characteristics through a hydrometeor classification algorithm (HCA)—inter-compared between X- and S-band for performance evaluation—including a hail and debris class and (2) kinematic properties of the low-level mesocyclone (LLM) assessed through <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><msub><mi>V</mi><mi>r</mi></msub></mrow></semantics></math></inline-formula> analyses. Four transient intensifications in <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><msub><mi>V</mi><mi>r</mi></msub></mrow></semantics></math></inline-formula> prior to tornadogenesis are documented and found to be associated with two prevalent internal rear-flank downdraft (RFD) momentum surges, the latter surge coincident with tornadogenesis. The momentum surges are marked by a rapidly advancing reflectivity (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>Z</mi><mi>H</mi></msub></semantics></math></inline-formula>) gradient traversing around the LLM, descending reflectivity cores (DRCs), a drop in differential reflectivity (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>Z</mi><mrow><mi>D</mi><mi>R</mi></mrow></msub></semantics></math></inline-formula>) due to the advection of smaller drops into the hook echo, a decrease in correlation coefficient (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>ρ</mi><mrow><mi>h</mi><mi>v</mi></mrow></msub></semantics></math></inline-formula>), and the detection of debris from the HCA. Additionally, volumetric analyses of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>Z</mi><mrow><mi>D</mi><mi>R</mi></mrow></msub></semantics></math></inline-formula> and specific differential phase (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>K</mi><mrow><mi>D</mi><mi>P</mi></mrow></msub></semantics></math></inline-formula>) signatures show general diffusivity of the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>Z</mi><mrow><mi>D</mi><mi>R</mi></mrow></msub></semantics></math></inline-formula> arc even after tornadogenesis in contrast with explosive deepening of the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>K</mi><mrow><mi>D</mi><mi>P</mi></mrow></msub></semantics></math></inline-formula> foot downshear of the updraft. Similarly, while the vertical extent of the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>Z</mi><mrow><mi>D</mi><mi>R</mi></mrow></msub></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>K</mi><mrow><mi>D</mi><mi>P</mi></mrow></msub></semantics></math></inline-formula> columns decrease leading up to tornadogenesis, the phasing of these signatures are offset after tornadogenesis, with the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>Z</mi><mrow><mi>D</mi><mi>R</mi></mrow></msub></semantics></math></inline-formula> column deepening the lagging of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>K</mi><mrow><mi>D</mi><mi>P</mi></mrow></msub></semantics></math></inline-formula>.
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