Reasons for the Unusually Destructive 2004 Atlantic Basin Hurricane Season

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Reasons for the Unusually Destructive 2004
Atlantic Basin Hurricane Season Phil Klotzbach
and William Gray Department of Atmospheric
Science Colorado State University Climate
Diagnostics Workshop October 25, 2005
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Outline

• 2004 Atlantic Hurricane Summary
• Activity-Enhancing Features
• Westward Track-Enhancing Features
• Conclusions

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Outline

• 2004 Atlantic Hurricane Summary
• Activity-Enhancing Features
• Westward Track-Enhancing Features
• Conclusions

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2004 ATLANTIC BASIN TROPICAL CYCLONE ACTIVITY
Forecast Parameter and 1950-2000 Climatology (in parentheses) Observed Activity
Named Storms (NS) (9.6) 14
Named Storm Days (NSD) (49.1) 90
Hurricanes (H) (5.9) 9
Hurricane Days (HD) (24.5) 46
Intense Hurricanes (IH) (2.3) 6
Intense Hurricane Days (IHD) (5.0) 22
Net Tropical Cyclone Activity (NTC) (100) 229
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2005 Season
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2004 Storm Tracks
Figure taken from http//www.nhc.noaa.gov/tracks/2
004atl.gif
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2005 Storm Tracks
Figure taken from http//www.wunderground.com/hurr
icane/at2005.asp
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9 Landfalls
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2004 United States Hurricane Landfalls
Name Date Landfall Location Landfall Intensity (kts) Insured Damage (Millions)
Charley Landfall 1 8/13 Cayo Costa, FL 130 7000
Charley Landfall 2 8/14 Cape Romain, SC 70 50
Frances 9/5 Hutchinson Island, FL 90 4500
Gaston 8/29 Awendaw, SC 65 65
Ivan 9/16 Gulf Shores, AL 105 7000
Jeanne 9/26 HutchinsonIsland, FL 105 3500
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Outline

• 2004 Atlantic Basin Statistics
• Activity-Enhancing Features
• Westward Track-Enhancing Features
• Conclusions

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August-September 2004 SST Anomalies
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?
1860 1900
1940 1980
2020
Adapted from Goldenberg et al. 2001
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August-September 2004 850 MB U Anomaly
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August-September 2004 V Anomalies
Anomalous Northerlies
200 mb
Anomalous Southerlies
850 mb
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August-September 2004 OLR Anomaly
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(No Transcript)
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Genesis Parameter (GP) Definition
GP ?V U850mb SSTA
Where ?V 850 mb 200 mb average
August-September V wind component from (7.5N
7.5S, 20-45W) U850mb 850 mb average
August-September U wind component from (5-15N,
20-60W) SSTA Average August-September sea
surface temperature anomaly from (5-15N,
20-60W)
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Genesis Parameter (GP) Component Locations
SSTA U
1.5 km
V
1.5 km
12 km
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Genesis Parameter Values (in Standard Deviations)
Period ?V U850mb SST Genesis Parameter Aug-Sep Named Storm Formations South of 25N
1950-1969 -0.1 0.8 0.0 0.3 4.7
1970-1994 -0.4 -0.8 -0.4 -0.7 3.3
1995-2003 1.2 0.4 0.9 1.2 5.4
2004 2.3 (2) 0.5 (17) 1.8 (3) 2.2 (2) 9 (T-1)
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Atlantic Basin Genesis Parameter Ratios
Ratio Named Storm Formations south of 25N Ratio
Highest 5 / Lowest 5 33 / 14 (2.41)
Highest 10 / Lowest 10 58 / 21 (2.81)
Highest 25 / Lowest 25 132 / 77 (1.71)
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August-September SST (1995-2004) (1950-1969)
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August-September 200 mb U (1995-2004)
(1950-1969)
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Upper-Level Wind Parameter (UP) Definition
UP -ZWA
Where ZWA 200 mb average August-September U
wind component from (5-15N, 20-60W)
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Upper-Level Wind Parameter (UP) Location
- ZWA
12 km
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Upper-Level Wind Parameter Values (in Standard
Deviations)
Period UP
1950-1969 0.5
1970-1994 -0.3
1995-2003 -0.3
2004 -0.2
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Outline

• 2004 Atlantic Basin Statistics
• Activity-Enhancing Features
• Westward Track-Enhancing Features
• Conclusions

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FRAN
OPAL
BRET
1995-2003 Intense Hurricane Tracks (32 tracks)
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August-September 500 mb Ht. (2004) (1995-2003)
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August-September 500 mb Ht. (2004) (1995-2003)
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Westward Track Parameter (WP) Definition
WP Zone 1 Zone 2 Zone 3
Where Zone 1 500 mb average August-September
500 mb height from (40-50N, 65-75W) Zone 2
500 mb average August-September 500 mb height
from (50-60N, 20-30W) Zone 3 500 mb average
August-September 500 mb height from (40-50N,
100-110W)
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L
L
H
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United States Tropical Cyclone Landfall Parameter
(LP) Definition
LP GP UP WP
Where GP Genesis Parameter UP Upper-Level
Wind Parameter WP Westward Track Parameter
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United States Landfall Parameter (LP) Values (in
Standard Deviations)
Period GP (Genesis) UP (Upper-Level Winds) WP (Track) LP (Landfall) Aug-Sep US Hurricane Landfalls
1950-1969 0.3 0.5 0.0 0.5 1.4
1970-1994 -0.7 -0.3 0.0 -0.7 1.0
1995-2003 1.2 -0.3 -0.1 0.5 1.0
2004 2.2 (2) -0.2 (31) 1.1 (5) 2.0 (2) 6 (1)
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United States Landfall Parameter Ratios
Ratio Named Storm Ratio Hurricane Ratio Intense Hurricane Ratio
Highest 5 / Lowest 5 21 / 7 (31) 13 / 3 (4.31) 7 / 2 (3.51)
Highest 10 / Lowest 10 32 / 12 (2.71) 19 / 4 (4.81) 11 / 2 (5.51)
Highest 25 / Lowest 25 64 / 43 (1.51) 37 / 23 (1.61) 22 / 9 (2.41)
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Outline

• 2004 Atlantic Basin Statistics
• Activity-Enhancing Features
• Westward Track-Enhancing Features
• Conclusions

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Conclusions

• The 2004 hurricane season was very active both in
  terms of overall tropical cyclone activity and in
  terms of United States landfalls
• A strong Intertropical Convergence Zone, weaker
  trade winds, and warm Atlantic sea surface
  temperatures contributed to the very active
  season
• A mid-level ridge predominated over the East
  Coast of the United States with mid-level troughs
  to the west and east which helped push storms
  westward into the longitudes of the United States