The 2004 Atlantic Hurricane Season and Beyond

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The 2004 Atlantic HurricaneSeason and Beyond

• Chris Landsea
• NOAA/Hurricane Research Division
• Miami, Florida, USA
• January and February 2004
• Southern Region Marine Workshop

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Outline

• Why have hurricane damages gone way up?
• How have hurricanes changed in the past?
• What environmental factors control hurricanes?
• What will the next couple decades bring?
• How is seasonal hurricane forecasting done?
• How well did the forecasts do in 2003?
• What is expected at this point for 2004?

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NOAA Dork Logo
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Florida Coastal Population
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NORMALIZED DAMAGE is estimated economic damages
if past storms made landfall with present-day
societal conditions. ND f(inflation,
population, wealth) Source Pielke, Jr., R.
A., and C. W. Landsea, 1998 Normalized Hurricane
Damages in the United States 1925-1995.
Weather and Forecasting, 13351-361.
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New England Major Hurricanes
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Atlantic Multidecadal Mode
Local Correlation of SST versus REOF
Mestas-Nunez and Enfield (1999)
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U.S. MAJOR LANDFALLING HURRICANES 1903-2000
Major East Coast Hurricanes
Inactive Decades
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Coverage of Low Tropospheric Vertical Wind Shear
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Strong Conveyor
Weak Conveyor
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Global Warming versus Society Changes Hurricane
Damages
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Dr. Bill Gray Colorado State University
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Sea Surface Temperatures
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Not too much "Wind Shear"
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La Nina versus El Nino Hurricane Probabilities
La Nina Hurricane Risk
El Nino Hurricane Risk
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The Global Mode Enhanced 200mb Subtropical
Ridges
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Global Mode Winter 98-99 To 99
Hurricane Season
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Global Mode Winter 96-97 To 97
Hurricane Season
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NOAA Forecast Methodology 1) Assess state of
Global Mode currently 2) Determine probabilities
of active/near-average/quiet, given persistence
of conditions through season 3) Adjust
probabilities depending upon anticipated
Atlantic Multidecadal Mode and El Nino-Southern
Oscillation phases

For example Early August 2001 indicated a
near-average global mode This would typically
suggest 25 active/50 near-average/25
quiet After stratifying for WARM Atlantic Mode
and neutral ENSO 40 active/40
near-average/20 quiet.
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NOAA 2003 Atlantic Hurricane Outlook
19 May, 2003 There is a 35 probability of a
near-normal Atlantic hurricane season in 2003, a
55 probability of an above-normal season, and a
10 chance of a below-normal season This outlook
reflects the ongoing multi-decadal conditions,
combined with a 70 chance of La Niña, both of
which are conducive to increased activity during
the normal peak (August-October) of the hurricane
season. The 2003 outlook calls for 11-15
tropical storms, with 6-9 becoming hurricanes,
and 2-4 becoming major hurricanes.
7 August, 2003 There is a 35 probability of a
near-normal Atlantic hurricane season in 2003, a
60 probability of an above-normal season, and a
5 chance of a below-normal season La Nina has
not developed as expected. Nonetheless, the
expected conditions combined with the active
phase of the Atlantic multi-decadal signal are
conducive to an above-normal Atlantic hurricane
season Historical data for similar climate
conditions indicates a likely range of 12-15
tropical storms this season, 7-9 hurricanes, and
3-4 major hurricanes.
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Hurricane Isabel 18 September 2003
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Historical Perspective ACE Index
Atlantic Basin Main Development
Region
Above Normal Season
Near Normal
Below Normal Season
2003 Predicted Range
Active Decades ACE 114 10 TS, 6.5 H, 3 MH
Active Decade ACE 134 13 TS, 8 H, 3.6
MH
IN-active Decades ACE 65 9 TS, 5 H, 1.5 MH
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NOAA Seasonal Atlantic Hurricane Outlook May
Forecast vs. Observed 1999-2003
Hurricanes
Tropical Storms
16
15
14
9
12
8
8
12
7
4
Major Hurricanes
ACE Index
206
5
200
4
135
3
3
122
2
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Observed
Forecast Range
Green bars show climatological mean and ACE range
for near-normal season (76-120 of Median)
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NOAA Seasonal Atlantic Hurricane Outlook August
Forecast vs. Observed 1998-2003
Hurricanes
Tropical Storms
16
10
15
14
9
14
8
8
7
12
12
4
ACE Index
Major Hurricanes
240
206
200
5
4
135
3
122
3
3
2
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Observed
Forecast Range
Green bars show climatological mean and ACE range
for near-normal season (76-120 of Median)
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The Global Mode January 2004
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Global Ocean Temperature Anomalies
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El Nino Forecasts For 2004
El Nino
La Nina
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Outline

• Why have hurricane damages gone way up?
• How have hurricanes changed in the past?
• What environmental factors control hurricanes?
• What will the next couple decades bring?
• How is seasonal hurricane forecasting done?
• How well did the forecasts do in 2003?
• What is expected at this point for 2004?

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