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Holly A. Anderson Department of Meteorology Florida State University Tallahassee, FL

Total Lightning and Radar Signatures in the “Freak” Shuttle-Damaging Hailstorm at Kennedy Space Center. Holly A. Anderson Department of Meteorology Florida State University Tallahassee, FL. Purpose of This Study.

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Holly A. Anderson Department of Meteorology Florida State University Tallahassee, FL

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  1. Total Lightning and Radar Signatures in the “Freak” Shuttle-Damaging Hailstorm at Kennedy Space Center Holly A. Anderson Department of Meteorology Florida State University Tallahassee, FL

  2. Purpose of This Study Determine what factors led to the rapid intensification of the hailstorm near Cape Canaveral. Analyze radar-derived and total lightning storm attributes through the storm’s lifetime.

  3. Data Sources • National Lightning Detection Network (NLDN) and KSC’s Cloud-to-Ground Surveillance System (CGLSS) data • KSC’s Lightning Detection and Ranging (LDAR) data • WSR-88D Level II radar data from Melbourne, FL (KMLB) • Rapid Update Cycle 20-km (RUC-20) Model Analysis data • Data were ingested into the Warning Decision Support System – Integrated Information (WDSS-II), a suite of algorithms used to display, merge, and analyze multiple data sources.

  4. WDSS-II Clustering a) Merged Composite reflectivity and b) the clusters based on composite reflectivity at 2210 UTC • Using the WDSS-II data mining algorithm, storms were clustered based on 30 dBZ of composite reflectivity. • Storm attributes can be tracked from any gridded field (Lightning density, echo top height, VIL, etc.) within that cluster. a) b)

  5. Space Shuttle Atlantis’ Hail Damage • 26 February 2007 • The hail damaged the foam insulation on the external tank. • About 26 heat shield tiles were damaged. • The launch was suspended until June so that repairs could be made. • Photo credit: NASA/Troy Cryder

  6. The Synoptic Setup • Westerly winds dominated central Florida as the subtropical jet advected moisture from the Gulf of Mexico. • A weak frontal boundary to the north tracked slowly to the southeast towards KSC. Visible satellite image from 2030 UTC

  7. The Near-Storm Environment The skies cleared ahead of the front long enoughto allow diabatic heating to increase CAPE from a weak 906 J/kg at 1200 UTC to a higher1818 J/kg at 2100 UTC.

  8. BWER and the Hail Aloft A BWER is evident from 2159-2209 UTC

  9. Hail Shaft Extending to Ground White arrows denote mean 0-6 km wind.

  10. 60-min Hail Swath Maximum MESH: 63.15 mm or 2.48 in. Hail swath for the 60-minutes preceding 2223 UTC

  11. Total Lightning and Updraft Strength • Total lightning activity can indicate updraft strength in a storm and therefore storm severity (Deierling et al., 2008). • Other studies have studied increases in IC lightning flash activity, called “lightning jumps”, prior to severe weather (Gatlin, 2006 and Schultz et al., 2008). • This study uses the maximum vertically integrated total lightning sources, known as Vertically Integrated LMA (VILMA) to diagnose total lightning activity.

  12. VILMA and D(VILMA)/DT • The peak VILMA occurs at 2208 UTC.

  13. Reflectivity and Total Lightning • There is no CG lightning from 2154 to 2159 UTC. • A “lightning jump” is evident at 2200 UTC in both LDAR and CG data. • The maximum reflectivity value of 71 dBZ observed from 2208 to 2211 UTC certainly suggests the presence of large hydrometeors, such as hail. • CG flash activity ends before IC flash activity ends.

  14. Reflectivity and Hail Parameters • The maximum MESH peaks at 63.15 mm (2.48 in) from 2208 to 2210 UTC. • Probability of Severe Hail (POSH) is 100% from 2208 to 2211 UTC. • Vertically Integrated Liquid (VIL) peaks earlier at 2206 UTC at 53.6 kg/m3. • Hail may have begun to precipitate out of the cloud just after 2206 UTC.

  15. Reflectivity Heights • The height of various reflectivity surfaces in relation to isotherms such as 0°C and -10°C has been studied to predict the likelihood of lightning (Wolf et al., 2006). • Higher echo tops and higher heights above isotherms would correlate to more intense lightning and a possibility of larger hail due to stronger updrafts.

  16. Echo Tops and Reflectivity Heights • The 18 dBZ echo top is at 11.46 km at 2200 UTC, ten minutes before the hail report. It grows and reaches its maximum height of 14.21 km from 2215- 2217 UTC. • The maximum of the 30 dBZ echo above -10°C, 7.86 km, occurs at 2212 UTC. • The average height of the 50 dBZ echo above 0°C reaches 3.88 km at 2210 UTC.

  17. Conclusions • Though shear and SRH were relatively weak, clear skies over KSC allowed daytime heating to increase CAPE for preexisting convection to rapidly intensify. • IC “lightning jumps” precede the severe weather 10 minutes and by 30 minutes. • As the updrafts increased: • the echo tops and reflectivity heights above isotherms increased • the charging region in the cloud increased in volume • the lightning flash activity increased • The precipitation of hail at 2210 UTC is concurrent with reflectivity level height falls. • Ice precipitating out of the cloud would result in decreasing radar reflectivity returns.

  18. Questions? A classic “Bolt from the Blue” at 2150 UTC (Just prior to passing over Launch Pad 39A)

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