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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. • Are there any notable signatures in lightning activity or reflectivities? • What can these signatures tell us about the storm’s updraft and hail production?

  3. Data Sources • National Lightning Detection Network (NLDN) and KSC’s Cloud-to-Ground Surveillance System (CGLSS) data – An integrated cloud-to-ground (CG) lightning dataset • KSC’s Lightning Detection and Ranging (LDAR) data – Individual in-cloud (IC) sources, or “stepped leaders” of lightning flashes • WSR-88D Level II radar data from Melbourne, FL (KMLB) • Rapid Update Cycle 20-km (RUC-20) Model Analysis data – Offers a look at the near-storm environment (NSE) to yield instability, shear, and moisture parameters • Storm Prediction Center preliminary storm report data • With the exception of SPC storm data, data were ingested into the Warning Decision Support System – Integrated Information (WDSS-II), a suite of algorithms used to 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, less than one minute before high wind and large hail was reported to the SPC. The lime green dashes are CG flashes. • The WDSS-II data mining algorithm (w2segmotionll) allows us to cluster storms based on a threshold value in a spatial field (30 dBZ of composite reflectivity for this case) to track various parameters 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 • KENNEDY SPACE CENTER, FL • “In late February, while Atlantis was on the launch pad, Atlantis' external tank received hail damage during a severe thunderstorm that passed through the Kennedy Space Center Launch Complex 39 area. The hail caused visible divots in the giant tank's foam insulation, as well as minor surface damage to about 26 heat shield tiles on the shuttle's left wing. The shuttle was returned to the VAB for repairs.” • Photo credit: NASA/Troy Cryder

  6. SPC Storm Reports 2210 200 KENNEDY SPACE CENTER BREVARD FL 2852 8068 SWATH OF 1 TO 2 INCH HAIL FOR A 5 MINUTE DURATION, ACCUMULATING SEVERAL INCHES IN SPOTS FROM THE VEHICLE ASSEMBLY BUILDING EASTWARD TO THE COAST. NUMEROUS AUTOMOBILES D (MLB) 2210 72 KENNEDY SPACE CENTER BREVARD FL 2864 8071 USAF WIND TOWER 211 (MLB) Two-inch diameter hail and a wind gust of 72 mph (63 kts) were reported at KSC at 2210 UTC, or 5:10 pm EST. Hail-damaged foam insulation on Atlantis

  7. 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. • Interaction between the subtropical jet and this frontal boundary provided the necessary uplift to trigger thunderstorms over west central Florida. Visible satellite image from 2030 UTC

  8. 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.

  9. The WDSS-II K-Means cluster-derived storm track, based on the storm’s centroid. Wind and hail report locations are indicated.

  10. Radar Reflectivity 0.5° plan view WSR-88D radar reflectivity from 2120 UTC – 2220 UTC

  11. A BWER and the Hail Aloft Holy smokes! It’s a BWER!

  12. Hail Shaft Extends to Ground White arrows denote mean 0-6 km wind.

  13. 60-min Hail Swath Maximum MESH: 63.15 mm or 2.48 in. Hail swath for the 60-minutes preceding 2223 UTC Note that the maximum MESH values occur near Launch Pad 39A.

  14. Total Lightning and Updraft Strength • Many studies have related total lightning activity to updraft strength in a storm (Deierling et al., 2008). • Total lightning activity can indicate the overall strength of the updraft in a thunderstorm. • Because of electrification processes, increased lightning activity can suggest a storm’s updraft has intensified. • Other studies have studied increases in IC lightning flash activity prior to severe weather (Gatlin, 2006 and Schultz et al., 2008). Called “lightning jumps”, these often occur prior to severe weather at the surface. • This study differs from previous “lightning jump” studies in that it uses the maximum vertically integrated total lightning sources, known as Vertically Integrated LMA (VILMA), instead of consolidating LDAR/LMA sources into distinct IC flashes.

  15. VILMA and D(VILMA)/DT • The LDAR source derivative, D(VILMA)/DT, shows an initial lightning “jump” (Gatlin, 2006) and (Schultz, 2008) occurs 30 minutes before hail at the surface. A larger “jump” occurs just 10 minutes prior to the severe weather. • The peak VILMA occurs at 2208 UTC.

  16. 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 lightning jump is collocated with the maximum in reflectivity during the storm’s lifetime. • 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.

  17. 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.

  18. Reflectivity Heights • The height of various reflectivity surfaces in relation to meteorologically significant isotherms, such as 0°C and -10°C, have been studied to predict the likelihood of lightning (Wolf et al., 2006). • Stated generally, the higher a reflectivity surface is above an isotherm such as the freezing level, the larger we would expect the volume of the region to be where thunderstorm electrification occurs. • We would expect that higher echo tops and higher heights above isotherms would correlate to more intense lightning and a possibility of larger hail.

  19. Echo Tops and Reflectivity Heights • Growing echo tops indicate the updraft was intensifying and could support large hail, as was observed. • The maximum in the average height of the 30 dBZ echo above -10C is collocated with the hail report at the surface. • This serves as a proxy for how large the area of electrification is.

  20. Conclusions • The rapid intensification of the severe thunderstorm was prompted by the interaction between the subtropical jet and a weak frontal boundary. • Though shear and SRH were negligible, clear skies over KSC allowed daytime heating to increase CAPE for convection to occur. • Unlike previous studies which used the IC flash rate to calculate jumps, this study used the Vertically Integrated LMA (VILMA). A “lightning jump” is evident when using this parameter, as well as in CG lightning flash density. • A small IC “lightning jump” precedes the sever weather at the surface by 30 minutes, supporting earlier work by Schultz and Gatlin. A much larger jump precedes the hail by just 10 minutes. • The maximum in reflectivity as well as a maximum in 30 dBZ echo above the -10C isotherm is collocated with the report of hail. This could indicate that the volume of the cell above this level is the largest at this time. We can infer this is the time of maximum updraft strength. • The increase in total lightning observed prior to the hailstorm serves to indicate the increase in the strength of the electrification processes occurring in the storm. As the strength of the updraft increase, and the storm becomes enhanced electrically. Increased total lightning is observed.

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

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