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

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• 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

2004 TC Tornado CountsTC 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

2005 TC Tornado CountsTC 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

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

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

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)

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)

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)

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!

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

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

Case studies

Ivan (2004)

IVAN

Sounding, Tallahassee, 00 UTC

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

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

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

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

Case study

Beryl 1994

T. S. BerylSurfaceAnalysis

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+FC afterfinal CG

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!

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

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

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