Total Lightning Observations of Supercells over North Central Texas - PowerPoint PPT Presentation

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Total Lightning Observations of Supercells over North Central Texas
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Total Lightning Observations of Supercells over North Central Texas

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  1. Total Lightning Observations of Supercells over North Central Texas Chris McKinney Larry Carey, Greg Patrick, Richard Orville

  2. Goals • Evaluate visual signatures of supercell intensity/severity, structure, and movement in total lightning data used at WFO FWD • emphasis on Flash Extent Density (FED) • Compare trends in FED to those in VHF total flash rate, a previously researched quantity • Compare total lightning displays to structure and intensity data from Doppler weather radar • radar reflectivity and velocity

  3. D/FW LDAR-II Network • Nine sensor VHF network owned by Vaisala • Seven sensors operational during dates in this study Adapted from Patrick and Demetriades (2005)

  4. Flash Extent Density • Gridded measure of VHF flash detection • 2 km x 2 km grid • display is number of individual flashes passing through each grid box

  5. 25 April 2005 • Two tornadic supercells over the southern half of the DFW metroplex • Five tornadoes reported, as well as numerous severe hail reports

  6. Lightning Hole

  7. Second Lightning Hole • Another lightning hole occurs with same cell at 2234 UTC • FED imagery “fills in” the lightning hole compared to GSD CW from top left: 6-9km GSD, 9-12km GSD, 12-15km GSD, and FED (0-20km)

  8. 05 April 2005 • Linear MCS moves across D/FW network • Left moving supercell located within the line moves across central Dallas County Time series of 0.5° reflectivity from KFWS WSR-88D, 2309 - 2339 UTC

  9. FED Appendages

  10. 13 April 2007 • Linear MCS with an embedded supercell moved across North Texas • Three tornadoes reported in Tarrant/Dallas counties, including EF-1 tornado in Haltom City

  11. FED Rear Notch 2326 UTC 13 April 2007 2354 UTC 13 April 2007

  12. Updraft Notch

  13. FED Rear Notch • KFWS images from 0001 UTC on April 6, 2005 • bowing reflectivity on 2.4° • outbound velocities 50-70kts • 50kt wind gust recorded near Allen, TX at 0015 UTC • top: 1.5º Z/V bottom: 2.4º Z/V

  14. FED Jumps

  15. Conclusions • FED displays important features of storm structure and evolution • updraft intensity, location and propagation • Identification of these features similar to early weather radar research (i.e., hook echoes) • LDAR data coverage aids in situations where radar cannot scan effectively • cone of silence • radar inoperative

  16. Conclusions • Trends in FED time series show some positive correlation to total flash rate • More work is needed to evaluate what is a significant “jump” in FED data

  17. Questions?