Transcript 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 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, 127
NC,VA,PA
MD,WV
4
7
Jeanne
26-28 Sep
FL,GA,SC, 42
NC,VA
1
1
Matthew
9 Oct
LA
0
0
1
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, 44
AL,GAVA
0
0
Dennis
9 Jul
FL
9
0
0
Emily
20 Jul
TX
11
0
0
Katrina
26-31 Aug
FL,GA,AL 58
MS,NC,PA
VA,OH
1
1
Rita
23-26 Sep
LA,AR,MS 92
AL,FL
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
H Beulah
H Frances
H Rita
H Andrew
H Katrina
H Georges
H Gilbert
H Cindy
H Jeanne
2004
1967
2004
2005
1992
2005
1998
1988
2005
2004
127
115
106
92
61
58
48
47
44
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 (03 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. Beryl
Surface
Analysis
*
*
*
*
*
*
*
+FC after
final 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
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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
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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