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

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

  • Tropical Cyclone TornadoesEugene W. McCaul, Jr.USRA HuntsvilleNSSTC/GHCC/SPoRT

  • 2004-2005 TC Tornadoes Smash All Previous RecordsCONUS hit by 15 tornadic TCs in 2004-52004 TC tornado count = 339, far larger than any other year (~15x normal)2005 TC tornado count is 224, ~10x normal2004-5 count alone almost = the full count in McCauls (1991) 39-yr climatology!For full details, see Grazulis

  • 2004 TC Tornado Counts

  • 2005 TC Tornado Counts

  • TC tornado outbreaks: numberBoth Frances (106) and Ivan (127) spawned more than 100 tornadoes; the first TCs to do so in 37 years; Rita came close with 921967s Beulah (115) relinquishes champ spot to Ivan (127)3 of all-time top 4 outbreaks, and 6 of top 10, occurred in 2004-5In the top 25 outbreaks, only 2004 and 2005 are represented with multiple storms

  • Top 10 TC Tornado Outbreaks

  • TC tornado outbreaks: severityFrances, Ivan, Rita spawned some F3s8 killer tornadoes overall from TCs in 2004-54 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 1972Through 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: character2004-5 TC tornado events well-behavedTended to form in NE or RF quadrants following TC recurvatureTended to form in large, intense TCsTended to form in TCs moving 4-8 m/s at landfallTended to form in weak baroclinic zones (old fronts, cool wedges, coastal fronts, etc)

  • TC tornado outbreaks: areasMost 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 patternAll 2004 TC tornadoes were confined to FL,GA, SC,NC,VA,MD,WV,PA; 2005 more widespreadLarge 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: recordsSeveral 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: recordsAugust 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: forecastsPotential for outbreaks was evident from synoptic and mesoscale analyses, at least for Frances, Ivan and JeanneFor the first time, SPC issued MDT RISK outlooks for these TCs, and they generally verified well

  • Case studiesIvan (2004)

  • IVAN

  • Sounding, Tallahassee, 00 UTC

  • Sounding characteristics - IvanBuoyant energy was not very large; CAPE near TLH apparently only ~1000 J/kgBuoyancy concentrated in lower troposphereVery strong veering shear in lower troposphere (0-3 km helicity ~600 J/kg)Environments support mini-supercells, with tornadoes, but no hail, little lightningSee 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 studyBeryl 1994

  • T. S. BerylSurfaceAnalysis

  • *******+FC afterfinal CG

  • Conclusions ITC tornado totals in 2004, 2005 unprecedentedTornado statistics in SE,E may be skewed for decades to come, thanks to Frances and IvanNWS,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 stormsMust rewrite parts of TC tornado FAQ at TPC!

  • Conclusions IITCs having enhanced tornado risk are:StrongLargeRecurving with midlatitude westerliesHodographs best downshear of TC centerGulf coast landfallersMoving at 4-8 m/sInteracting with weak fronts

  • Conclusions IIITC tornado swarms involve supercellsTC supercells most common in RF (NE) quad0-3 km helicity often > 150 J/kgCAPE often only 500-1000 J/kgStorms usually small, shallow, with little LTGMore LTG -> stronger storms, BUTLulls in CGs -> tornadoes (sometimes)Meso signatures hard to detect at r > 100 kmBeware of any persistent cells

  • AcknowledgmentsTom Grazulis, author of Significant Tornadoes, 1680-1991NWS personnel at TBW,MLB,JAX,TLH, ATL,CAE,CHS,GSP,ILM,MHX,RAH, RNK,AKQ,LWX,CTPJason Caldwell, SERCCPatrick Michaels, VA State ClimatologistDennis Buechler, UAHPlymouth State CollegeStorm Prediction Center