Tropical Cyclone Tornadoes

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Tropical Cyclone Tornadoes

• Eugene W. McCaul, Jr.
• USRA Huntsville
• NSSTC/GHCC/SPoRT

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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
  McCauls (1991) 39-yr climatology!
• For full details, see Grazulis website
• www.tornadoproject.com/alltorns/tcyclone1.html
• www.tornadoproject.com/alltorns/tcyclone2.html

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2004 TC Tornado Counts
TC names Dates States Number Killers Deaths
Bonnie 12 Aug FL,GA,SC NC,VA 18 1 3
Charley 12-14 Aug FL,SC,NC VA 25 0 0
Gaston 29-30 Aug SC,NC,VA 20 0 0
Frances 4-8 Sep FL,GA,SC NC,VA 106 0 0
Ivan 15-19 Sep FL,GA,SC, NC,VA,PA MD,WV 127 4 7
Jeanne 26-28 Sep FL,GA,SC, NC,VA 42 1 1
Matthew 9 Oct LA 1 0 0
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2005 TC Tornado Counts
TC names Dates States Number Killers Deaths
Arlene 11 Jun FL,IN 3 0 0
Cindy 6 Jul FL,SC,NC, AL,GAVA 44 0 0
Dennis 9 Jul FL 9 0 0
Emily 20 Jul TX 11 0 0
Katrina 26-31 Aug FL,GA,ALMS,NC,PA VA,OH 58 1 1
Rita 23-26 Sep LA,AR,MS AL,FL 92 1 1
Tammy 5 Oct GA 1 0 0
Wilma 23 Oct FL 8 0 0
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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
• 1967s 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

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Top 10 TC Tornado Outbreaks
H Ivan 2004 127
H Beulah 1967 115
H Frances 2004 106
H Rita 2005 92
H Andrew 1992 61
H Katrina 2005 58
H Georges 1998 48
H Gilbert 1988 47
H Cindy 2005 44
H Jeanne 2004 42
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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 Ivans 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)

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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)

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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)

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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!

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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

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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

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Case studies

• Ivan (2004)

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IVAN
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Sounding, Tallahassee, 00 UTC
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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

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Tornado from Ivan, Panama City, FL, 15 Sep
2004 (US Navy
photo)
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Tornado, Loudon County, VA, 17 Sep 2004 (Ivan)
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Tornado, Orange County, VA, 17 Sep 2004 (Ivan)
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Case study

• Beryl 1994

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T. S. Beryl Surface Analysis
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FC after final CG







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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 (Bonnie3, Ivan4)
• Need to educate public better about the peculiar
  traits of TC tornadic storms
• Must rewrite parts of TC tornado FAQ at TPC!

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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

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Conclusions III

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

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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