1 / 26

A Review of the North Alabama Violent Tornado Outbreak

A Review of the North Alabama Violent Tornado Outbreak. February 6, 2008. Brian Carcione & David Nadler NWS Huntsville, Alabama. Overview. Modified version of presentation given to 7 th Annual Southeast Severe Storms Symposium

liam
Download Presentation

A Review of the North Alabama Violent Tornado Outbreak

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. A Review of the North Alabama Violent Tornado Outbreak February 6, 2008 Brian Carcione & David Nadler NWS Huntsville, Alabama

  2. Overview • Modified version of presentation given to 7th Annual Southeast Severe Storms Symposium • Focus on warning decision-making (warning forecaster’s perspective) • NWS NEXRAD Data • ARMOR Data • LMA in AWIPS and LMA trends • Food for thought/points for discussion

  3. Local Event Overview No additional tornado damagein Tennessee EF-4 3:00 to 3:20 AM EF-1 EF-45:17 to 5:34 AM EF-14:43 AM EF-1 EF-04:00 AM EF-2 EF-0 “Storm Track Map” – MESH Data from NSSL

  4. 09 & 11Z UTC SPC Mesoanalysis 0-1km SRH & Storm Motion MLCAPE (contour) & MLCIN (shaded)

  5. Storm-scale / Radar Analysis 0600-1100UTC 06 Feb 2008 Radar Mosaic

  6. KGWX 0.5_1.3° BR/SRM - 0859Z 06 Feb Lawrence County Tornado EF-4 tornado touching down around this time KGWX 0.5° base velocity 100+ kt KGWX: 62nm away, 0.5° angle elevation ~5700ft AGL

  7. KHTX 0.5_1.3° BR/SRM - 0906Z 06 Feb Lawrence County Tornado Rotational Velocity 109kt (81kt outbound, 28kt inbound) VR Shear = .0267 s-1 KHTX: 65nm away, 0.5° angle elevation ~7400ft AGL

  8. UAH ARMOR Data – 0848-0907Z 06 FebData interrogated & visualized with GR2Analyst 81kt rotational velocity 0.7° Base Reflectivity and Velocity ARMOR: 25-40nm away, 0.7° angle elevation ~2220-2970’ AGL

  9. UAH ARMOR Data – 0912-0915Z 06 Feb 99kt Base Velocity at 1700’ AGL 0.7° Base Reflectivity and Velocity ARMOR: 20-30nm away, 0.7° angle elevation ~1600-2000ft AGL

  10. LMA Data w/ KHTX Refl/SRM & LRM Lawrence County Storm - 0840Z Feb06 2008 Max source density ~ 36 as storm enters SW Lawrence County No tornado reported at this time

  11. LMA Data w/ KHTX Refl/SRM & LRM Lawrence County Storm - 0856Z Feb06 2008 Source density jumps to ~ 61

  12. LMA Data w/ KHTX Refl/SRM & LRM Lawrence County Storm - 0902Z Feb06 2008 Slight decrease in source density Tornado reported on the ground

  13. LMA Data w/ KHTX Refl/SRM & LRM Lawrence County Storm - 0906Z Feb06 2008 4 minutes later, source density diminishes significantly Tornado still on the ground

  14. Supercell-squall line merger EF-4 Tornado

  15. KHTX 0.5_1.3° BR/SRM - 1043Z 06 Feb Jackson County Tornado Brief EF-1 touchdown just north of Guntersville, AL

  16. KHTX 0.5_1.3° BR/SRM - 1115Z 06 Feb Jackson County Tornado

  17. KHTX 0.5_1.3° BR/SRM - 1125Z 06 Feb Jackson County Tornado Rotational Velocity 132kts at ~ 1500ft AGL (70kt inbound, 62kt outbound) Enhanced reflectivity indicates possible debris detection

  18. UAH ARMOR Data – 1118-1119Z 06 Feb 84kt velocity 87kt rotational velocity at 3680’ AGL 0.7° Base Reflectivity and Velocity ARMOR: ~45nm away, 0.7° angle elevation ~3700-4600ft AGL

  19. LMA Data w/ KHTX Refl/SRM & LRM Jackson County Storm - 1032Z Feb06 2008 Max source density ~ 105 No tornado reports yet

  20. LMA Data w/ KHTX Refl/SRM & LRM Jackson County Storm - 1038Z Feb06 2008 Significant decrease within 6 minutes Reflectivity suggests a more ‘classic’ supercell structure with more impressive updrafts EF-1 Tornado on the ground

  21. LMA Data w/ KHTX Refl/SRM & LRM Jackson County Storm - 1100Z Feb06 2008 Big jump as storm ascends Sand Mountain Reflectivity diminishing, perhaps becoming a lower-topped supercell No tornado on the ground at this time

  22. LMA Data w/ KHTX Refl/SRM & LRM Jackson County Storm - 1125Z Feb06 2008 Enhanced “white” area possible debris being detected by 88D base reflectivity Storm begins to weaken, supported by significant flash decrease EF-4 Tornado on the ground

  23. Ascending Sand Mountain EF-1 near Guntersville EF-4 Tornado

  24. Food for Thought: ARMOR • ARMOR samples most of the ‘central’ HUN CWFA better than any NWS NEXRAD • Would have been more useful to ascertain reflectivity structure • Has some unique limitations • Many forecasters are eager to use and learn about the ARMOR data • GR2Analyst makes it more readily available • Dual-pol upgrade will make that data more accessable as well • COMET partnership to make data available in AWIPS will be a key

  25. Food for Thought: LMA • Tertiary data source during this event—radars, reports, upstream conditions, etc. were of greater importance • HUN forecasters traditionally look for jumps/drops in LMA data based on earlier research (~2001-2004) • This case does not disprove that, but does show weaknesses in an overly-simplistic methodology • Cool season vs. warm season environments—not all storms are created equal • Distance/sampling concerns similar to those with radar data • Difficulty in visualizing & analyzing LMA data (trends, color tables, etc.) • More research, better visualization techniques, training refreshers will help

  26. Questions or Comments? Brian.Carcione@noaa.gov David.Nadler@noaa.gov http://weather.gov/huntsville Thanks to Chris Darden and our NASA and UAH partners

More Related