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Explore factors contributing to the unusually destructive 2004 Atlantic hurricane season with detailed summaries, statistical analyses, and conclusions. Learn about activity and track-enhancing features, including SST anomalies and genesis parameter values. Discover how the atmospheric conditions influenced the high hurricane and landfall rates, with notable storm track patterns.
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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
Outline • 2004 Atlantic Hurricane Summary • Activity-Enhancing Features • Westward Track-Enhancing Features • Conclusions
Outline • 2004 Atlantic Hurricane Summary • Activity-Enhancing Features • Westward Track-Enhancing Features • Conclusions
2004 Storm Tracks Figure taken from http://www.nhc.noaa.gov/tracks/2004atl.gif
2005 Storm Tracks Figure taken from http://www.wunderground.com/hurricane/at2005.asp
Outline • 2004 Atlantic Basin Statistics • Activity-Enhancing Features • Westward Track-Enhancing Features • Conclusions
? 1860 1900 1940 1980 2020 Adapted from Goldenberg et al. 2001
August-September 2004 V Anomalies Anomalous Northerlies 200 mb Anomalous Southerlies 850 mb
Genesis Parameter (GP) Definition GP = ΔV + U850mb + SSTA Where: ΔV = 850 mb – 200 mb average August-September V wind component from (7.5°N – 7.5°S, 20°-45°W) U850mb = 850 mb average August-September U wind component from (5°-15°N, 20°-60°W) SSTA = Average August-September sea surface temperature anomaly from (5°-15°N, 20°-60°W)
Genesis Parameter (GP) Component Locations SSTA + U 1.5 km V 12 km 1.5 km
Upper-Level Wind Parameter (UP) Definition UP = -ZWA Where: ZWA = 200 mb average August-September U wind component from (5°-15°N, 20°-60°W)
Upper-Level Wind Parameter (UP) Location - ZWA 12 km
Outline • 2004 Atlantic Basin Statistics • Activity-Enhancing Features • Westward Track-Enhancing Features • Conclusions
FRAN OPAL BRET 1995-2003 Intense Hurricane Tracks (32 tracks)
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°-50°N, 65°-75°W) Zone 2 = 500 mb average August-September 500 mb height from (50°-60°N, 20°-30°W) Zone 3 = 500 mb average August-September 500 mb height from (40°-50°N, 100°-110°W)
L L H
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
United States Landfall Parameter (LP) Values (in Standard Deviations)
Outline • 2004 Atlantic Basin Statistics • Activity-Enhancing Features • Westward Track-Enhancing Features • Conclusions
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