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Tropical Cyclone Tornadoes

Tropical Cyclone Tornadoes. Eugene W. McCaul, Jr. USRA Huntsville NSSTC/GHCC/SPoRT. 2004-2005 TC Tornadoes Smash All Previous Records. CONUS hit by 15 tornadic TCs in 2004-5 2004 TC tornado count = 339, far larger than any other year (~15x normal) 2005 TC tornado count is 224, ~10x normal

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Tropical Cyclone Tornadoes

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  1. Tropical Cyclone Tornadoes Eugene W. McCaul, Jr. USRA Huntsville NSSTC/GHCC/SPoRT

  2. 2004-2005 TC Tornadoes Smash All Previous Records • CONUS hit by 15 tornadic TCs in 2004-5 • 2004 TC tornado count = 339, far larger than any other year (~15x normal) • 2005 TC tornado count is 224, ~10x normal • 2004-5 count alone almost = the full count in McCaul’s (1991) 39-yr climatology! • For full details, see Grazulis website: • www.tornadoproject.com/alltorns/tcyclone1.html • www.tornadoproject.com/alltorns/tcyclone2.html

  3. 2004 TC Tornado Counts

  4. 2005 TC Tornado Counts

  5. TC tornado outbreaks: number • Both Frances (106) and Ivan (127) spawned more than 100 tornadoes; the first TCs to do so in 37 years; Rita came close with 92 • 1967’s Beulah (115) relinquishes champ spot to Ivan (127) • 3 of all-time top 4 outbreaks, and 6 of top 10, occurred in 2004-5 • In the top 25 outbreaks, only 2004 and 2005 are represented with multiple storms

  6. Top 10 TC Tornado Outbreaks

  7. TC tornado outbreaks: severity • Frances, Ivan, Rita spawned some F3s • 8 killer tornadoes overall from TCs in 2004-5 • 4 killer tornadoes from one TC, Ivan (first time since 1891, according to Grazulis) • One of Ivan’s tornadoes killed 4; largest TC tornado death toll since 1972 • Through 30 Sep 2004, 6 of 14 CONUS killer tornadoes in 2004 were from TCs; 11 of 27 deaths; 7 deaths occurred from nocturnal tornadoes (Bonnie, Ivan)

  8. TC tornado outbreaks: character • 2004-5 TC tornado events “well-behaved” • Tended to form in NE or RF quadrants following TC recurvature • Tended to form in large, intense TCs • Tended to form in TCs moving 4-8 m/s at landfall • Tended to form in weak baroclinic zones (old fronts, cool wedges, coastal fronts, etc)

  9. TC tornado outbreaks: areas • Most tornadic TCs made landfall on Gulf coast, (except Frances, Jeanne, Gaston, Tammy) • TC tracks in 2004 were channeled inland up the Appalachians or Atlantic coast by persistent synoptic-scale trough pattern • All 2004 TC tornadoes were confined to FL,GA, SC,NC,VA,MD,WV,PA; 2005 more widespread • Large tornado swarms occurred in SC (Frances); nw FL (Ivan), and VA-MD (Ivan); AL-GA (Cindy); AL-GA (Katrina); MS-AL (Rita)

  10. TC tornado outbreaks: records • Several states established new maximum annual tornado counts because of TCs: • SC annual record now 82 (was 54) • VA annual record now 86 (was 32) • MS annual record now 99 (was 64) • AL annual record now 77 (was 55) • Both SC and VA now have max tornado counts larger than any eastern states except for IL, MS and FL!

  11. TC tornado outbreaks: records • August established a new max tornado count in 2004, with 182 (partly due to TCs) • September established a new max tornado count in 2004, with 297 (275 due to TCs) • 2004 total tornado count of 1819 smashes previous record of 1424 in 1998; TC contribution of 339 was important

  12. TC tornado outbreaks: forecasts • Potential for outbreaks was evident from synoptic and mesoscale analyses, at least for Frances, Ivan and Jeanne • For the first time, SPC issued MDT RISK outlooks for these TCs, and they generally verified well

  13. Case studies Ivan (2004)

  14. IVAN

  15. Sounding, Tallahassee, 00 UTC

  16. Sounding characteristics - Ivan • Buoyant energy was not very large; CAPE near TLH apparently only ~1000 J/kg • Buoyancy concentrated in lower troposphere • Very strong veering shear in lower troposphere (0-3 km helicity ~600 J/kg) • Environments support mini-supercells, with tornadoes, but no hail, little lightning • See Watson et al poster for radar analyses

  17. Tornado from Ivan, Panama City, FL, 15 Sep 2004 (US Navy photo)

  18. Tornado, Loudon County, VA, 17 Sep 2004 (Ivan)

  19. Tornado, Orange County, VA, 17 Sep 2004 (Ivan)

  20. Case study Beryl 1994

  21. T. S. Beryl Surface Analysis

  22. +FC after final CG * * * * * * *

  23. Conclusions I • TC tornado totals in 2004, 2005 unprecedented • Tornado statistics in SE,E may be skewed for decades to come, thanks to Frances and Ivan • NWS,SPC did well with watches, warnings, but 7 deaths occurred at night (Bonnie=3, Ivan=4) • Need to educate public better about the peculiar traits of TC tornadic storms • Must rewrite parts of TC tornado FAQ at TPC!

  24. Conclusions II • TCs having enhanced tornado risk are: • Strong • Large • Recurving with midlatitude westerlies • Hodographs best downshear of TC center • Gulf coast landfallers • Moving at 4-8 m/s • Interacting with weak fronts

  25. Conclusions III • TC tornado swarms involve supercells • TC supercells most common in RF (NE) quad • 0-3 km helicity often > 150 J/kg • CAPE often only 500-1000 J/kg • Storms usually small, shallow, with little LTG • More LTG -> stronger storms, BUT… • Lulls in CGs -> tornadoes (sometimes) • Meso signatures hard to detect at r > 100 km • Beware of any persistent cells

  26. Acknowledgments • Tom Grazulis, author of Significant Tornadoes, 1680-1991 • NWS personnel at TBW,MLB,JAX,TLH, ATL,CAE,CHS,GSP,ILM,MHX,RAH, RNK,AKQ,LWX,CTP • Jason Caldwell, SERCC • Patrick Michaels, VA State Climatologist • Dennis Buechler, UAH • Plymouth State College • Storm Prediction Center

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