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Open Rachelgutierrez Masters.Pdf The Pennsylvania State University The Graduate School ENVIRONMENTAL AND RADAR CHARACTERISTICS OF GARGANTUAN HAIL-PRODUCING STORMS A Thesis in Meteorology and Atmospheric Science by Rachel E. Gutierrez c 2019 Rachel E. Gutierrez Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science December 2019 The thesis of Rachel E. Gutierrez was reviewed and approved∗ by the following: Matthew Kumjian Associate Professor of Meteorology Thesis Advisor Paul Markowski Professor of Meteorology Associate Head, Graduate Program in Meteorology Anthony Didlake Assistant Professor of Meteorology David J. Stensrud Professor of Meteorology Department Head ∗Signatures are on file in the Graduate School. ii Abstract Storms that produce gargantuan hail (≥ 6 inches or 15 centimeters in maximum dimension), although seemingly rare, can cause extensive damage to property and infrastructure and cause injury to humans and animals. Additionally, gargantuan hail-producing storms can be responsible for billions of dollars worth of insured losses. Currently, we are limited in our ability to accurately predict gargantuan hail and detect gargantuan hail on radar. We analyze the environments and radar characteristics of gargantuan hail-producing storms to define the parameter space of environments in which gargantuan hail occurs, and compare environmental pa- rameters and radar signatures in these storms to other sizes of hail. We find that traditionally used environmental parameters used for hail prediction, such as most unstable convective available potential energy (MUCAPE), may not be able to distinguish between gargantuan hail environments and environments that produce smaller hail. Moreover, radar reflectivity does not appear to be able to distinguish among hail sizes. However, inferred rotational velocities within the hail growth region of the mesocyclone of storms that produce gargantuan hail are significantly stronger than the rotational velocities found for smaller hail. iii Table of Contents List of Figures vi List of Tables ix Acknowledgments x Chapter 1 Introduction 1 1.1 Motivation . 1 1.2 Background . 4 Chapter 2 Data 10 2.1 Cases . 10 2.2 Methods of Analysis . 12 2.2.1 Environments . 12 2.2.2 Radar . 15 Chapter 3 Results 18 3.1 Environmental Characteristics . 18 3.1.1 Synoptic Overview . 18 3.1.2 Environmental Parameters Analyses . 18 3.1.3 Comparison to Other Hail Environments . 19 3.1.4 Storm Motion Analysis . 25 3.1.5 0 oC Wet Bulb Heights . 27 3.1.6 Lapse Rates . 28 3.1.7 Significant Hail Parameter (SHIP) . 29 3.2 Radar Characteristics . 30 3.2.1 Analysis of ZH and HDR Swaths . 30 iv 3.2.2 Vertical Profiles of Reflectivity . 33 3.2.3 Bounded Weak Echo Region Area Analysis . 34 3.2.4 Rotational Velocity Analysis . 36 Chapter 4 Conclusions 48 Bibliography 53 v List of Figures 1.1 Examples of gargantuan hailstones. (a) and (b) are gargantuan hailstones from Wagner and Dante, SD, (US Department of Com- merce, NOAA, 2007) (c) is the gargantuan hailstone from Wichita, KS, (US Department of Commerce, NOAA, 2010b)(d) is the gar- gantuan hailstone from Vivian, SD, (US Department of Commerce, NOAA, 2010a) and (e) is the gargantuan hailstone from Villa Carlos Paz in Argentina (courtesy of Victoria Druetta). 2 1.2 Examples of gargantuan hail damage. (a) shows a hole in the roof of a home caused by gargantuan hail in Nisland, SD (Brunner, 2015). (b) and (c) show craters in the ground caused by gargantuan hail in Vivian, SD and Dante, SD, respectively (US Department of Commerce, NOAA, 2010a, 2007). 3 2.1 Map of all USA gargantuan hail cases (the Argentina gargantuan hail case is not included). 11 2.2 Sunray case soundings without (left) and with (right) the linear interpolation correction. 14 2.3 Comparison of the real environmental soundings to the RUC/RAP linear interpolated corrected soundings for the El Reno case. The wind barbs are of the real environmental winds. The bright hodo- graph colors represent the RUC/RAP model winds and the dark hodograph colors represent the real environmental winds. 16 2.4 Same as Figure 2.3 but for the Nisland case. 17 3.1 RAP generated soundings for all gargantuan hail cases with the linear interpolation correction applied to the surface T and Td. 20 3.2 RAP generated soundings for all gargantuan hail cases with the linear interpolation correction applied to the surface T and Td. 21 3.3 MUCAPE versus hailsize for the gargantuan hail cases. Brighter colored dots represent larger hail sizes. 22 3.4 MUCAPE versus 0{6 km Bulk Shear for the gargantuan hail cases. 22 vi 3.5 MUCAPE versus 0{3km SRH for the gargantuan hail cases. 23 3.6 MUCAPE versus hailsize for both the SPLASH and gargantuan hail cases. Results from Blair et al. (2017) are also shown. The whiskers are estimated from Figures 10 and 11 from Blair et al. (2017). 24 3.7 MUCAPE versus 0{6 km Bulk Shear for both the SPLASH and gargantuan hail cases. Results from Blair et al. (2017) are also shown. 25 3.8 MUCAPE versus 0{3 km SRH for both the SPLASH and gargan- tuan hail cases. 26 3.9 2D Kernel Density Estimate of the tracked storm motion minus the calculated RM Bunkers storm motion. The shading represents the probability density. 27 3.10 Boxplots of the 700{500 hPa and 850{700 hPa lapse rates for all gargantuan hail cases. The teal bar is the median, the magenta triangle is the mean, the box is the interquartile range, and the whiskers are the most extreme but non-outlier point. 30 3.11 Boxplot of the Significant Hail Parameter (SHIP) for all gargantuan hail cases. The teal bar is the median, the magenta triangle is the mean, the box is the interquartile range, and the whiskers are the most extreme but non-outlier point. 31 3.12 Maximum reflectivity swaths for all gargantuan hail cases. The large black dot on the swath represents the location of the gargan- tuan hailfall. 38 3.13 Kernel Density Estimate of the maximum reflectivity to occur at the gargantuan hailfall location (blue) and the maximum reflectivity to occur anywhere in the storm (magenta). The bandwidth used to create this was 2.5 dB. 39 3.14 Maximum hail differential reflectivity (HDR) swaths for the gargan- tuan hail cases that had dual-pol radar. 40 3.15 Kernel Density Estimate of the maximum hail differential reflectiv- ity to occur at the gargantuan hailfall location (green) and the max- imum hail differential reflectivity to occur anywhere in the storm (orange). The bandwidth used to create this was 4 dB. 41 3.16 Vertical profile of reflectivity for a 5 km x 5 km grid box centered on the gargantuan hailfall location as a function of temperature. The teal bars are medians, the magenta triangles are means, and the boxes are the interquartile ranges. Each box represents one elevation from one storm. 42 vii 3.17 Results from Ortega (2018) for non-severe hail, severe hail, and significantly severe hail (left) and our results for gargantuan hail (right). Our results show the median reflectivity for 5oC increments. Here, we see that gargantuan hail has similar if not slightly lower values of reflectivity for each elevation when compared to Ortega (2018). 43 3.18 Example showing the BWER area algorithm using the El Reno case. Here, one radial through the BWER is shown. (a) is the reflectivity along that radial, (b) is the moving average of that reflectivity, and (c) is the standard deviation of that moving average. The orange dots signify > 2 dB in the standard deviation of the moving average of reflectivity. This 2-dB flag captures the BWER bounds (significant dip in reflectivity and return to high reflectivity) for each radial throughout the BWER. 44 3.19 Examples of the largest BWERs for each case within the hail growth region. The black dot represents the gargantuan hailfall location. The Argentina BWER is not shown here. 45 3.20 Bounded Weak Echo Region (BWER) areas within the hail growth region before, during, and after the gargantuan hailfall. The teal bars are the medians, the magenta triangles are the means, the boxes are the interquartile range, the whiskers are the most extreme but non-outlier point, and the circles are the outliers. 46 3.21 Rotational velocities within the hail growth region before, during, and after the time of gargantuan hailfall. The teal bars are the medians, the magenta triangles are the means, the boxes are the interquartile range, the whiskers are the most extreme but non- outlier point, and the circles are the outliers. 46 3.22 Comparison of Blair et al. (2011) results (left) for hail ≥ 4 inches in maximum dimension (giant hail) to our results (right) for hail ≥ 6 inches in maximum dimension (gargantuan hail). The interquartile range and median are known and the whiskers are estimated from Blair et al. (2011). Our results show that there is a significant increase in rotational velocities for gargantuan hail from giant hail. 47 viii List of Tables 1.1 Typical hail sizing convention (Storm Prediction Center, 2019; Blair et al., 2011). Here, size refers to the hailstone's maximum dimen- sion. We propose a new size category, \gargantuan," that includes hailstones ≥ 6 inches or 15 centimeters in maximum dimension. 2 2.1 Gargantuan hail cases that are used in this study. Here, \hail size" refers to the hailstone's maximum dimension. 11 3.1 Lowest height above ground level (AGL) of the 0oC wet bulb tem- perature. 28 ix Acknowledgments This thesis would not be possible without the contributions from the following people. First of all, I would like to thank my advisor, Dr.
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