Atlantic Basin Seasonal Hurricane Forecasting

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Atlantic Basin Seasonal Hurricane
Forecasting Phil Klotzbach Department of
Atmospheric Science Colorado State
University NFS Products and Services
Conference September 13, 2007
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• Aragos Admonition
• Never, no matter what may be the progress of
  science, will honest scientific men who have
  regard for their reputations venture to predict
  the weather.

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So easy a caveman could do it.
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Outline

• Introduction
• Atlantic Basin Multi-Decadal Variability
• 2007 Atlantic Basin Hurricane Forecast
• United States Landfall Probability Webpage
• Hurricanes and Global Warming

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Introduction The globes atmosphere and oceans
function as one unit. Current circulation
features have considerable precursor information
regarding the coming months or coming seasons
amount of hurricane activity.
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OUTGOING LONGWAVE RADIATION
LATENT HEAT FLUX
SENSIBLE HEAT AND POTENTIAL ENERGY FLUX
ABSORBED SOLAR RADIATION
NET ENERGY BALANCE
SUBSURFACE HEAT STORAGE
THERMAL INERTIA
OCEAN HEAT FLUX
TEMPERATURE
Flow diagram for climate modeling, showing
feedback loops. From Robock
(1985).
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Atlantic Basin Multi-decadal Variability
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SURFACE
500 METERS
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Courtesy of John Marshall (MIT)
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THC - Strong
?
1860 1900
1940 1980
2020
(Goldenberg et al. 2001)
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SSTA
SSTA -




SLPA
SLPA
gyre -
gyre


STRONG THC
WEAK THC
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FAST
FAST
SLOW
SLOW
Thermohaline Circulation
Rate of Salt Buildup from (E-P) - River 0
Salt Anomaly (S1)
(S1)
(S1)
YEARS
30
60
90
120
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AMO Index
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1925-1965 41YEARS 24 IH
1966-2006 41YEARS 7 IH
54
38
55
0.17/year
0.59/year
44
33
85
54
55
54
96
60
59
89
28
04
49
33
47
50
26
45
05
65
92
48
04
44
50
29
60
35
? as frequent
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PENINSULA FLORIDA LANDFALLING MAJOR HURRICANES
1
3
11
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2007 Hurricane Season
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OBSERVED 2007 ATLANTIC BASIN TROPICAL CYCLONE
ACTIVITY THROUGH SEPTEMBER 10
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Observed 2007 Atlantic basin tropical cyclone
activity through September 10
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2007 Atlantic Basin Hurricane Forecasts and
Verifications
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2007 ATLANTIC BASIN SEASONAL HURRICANE FORECASTS
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New August Seasonal Forecast Predictors
Pre 1-August NSD S of 23.5N, E of 75W
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4
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June July SST
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EQ.
June July SLP
June July SST
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August Statistical Scheme Hindcast Skill for
NTC (1900-1948)
Observations
Hindcasts
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August Statistical Scheme Hindcast Skill for
NTC (1949-2005)
Observations
Hindcasts
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AUGUST 2007 FORECAST VERIFICATION
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SEPTEMBER 2007 FORECAST
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October-November 2007 Forecast
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Skill of Seasonal Forecasts

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The number of years that our tropical cyclone
forecasts issued at various lead times have
correctly predicted above- or below-average
activity for each predictand over the past eight
years (1999-2006)
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Correlation of CSU Seasonal Forecasts with
Observations over the period from 1984-2005 for
June and August, from 1992-2005 for December and
from 1995-2005 for April
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PROBABILITIES FOR AT LEAST ONE MAJOR (CATEGORY
3-4-5) HURRICANE LANDFALL ON EACH OF THE
FOLLOWING COASTAL AREAS FOR 2007

• Entire U.S. coastline 68 (average for last
  century is 52)
• 2) U.S. East Coast including Peninsula Florida -
  43 (average for last century is 31)
• 3) Gulf Coast from the Florida Panhandle
  westward to Brownsville - 43 (average for last
  century is 30)
• 4) Expected above-average major hurricane
  landfall risk in the Caribbean

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New Landfalling Hurricane Web Application

• Currently Available at the following URL

http//www.e-transit.org/hurricane
In partnership with the GeoGraphics Laboratory
Bridgewater State College, Bridgewater MA
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REGION 2 - TEXAS LOUISIANA
H
A
J
C
L
O
C
J
V
C
(c)
(b)
(a)
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Future Work

• Gust Probabilities
• Monthly Probabilities
• User-Selected Probabilities (Daily, Weekly
  Periods)
• Potential Damage

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Hurricanes and Global Warming
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ATLANTIC THC WEAK
CAT 3-4-5 TRACKS
ATLANTIC THC STONG
CAT 3-4-5 TRACKS
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1992-2006 15 YEARS 5 IH
1966-1991 26 YEARS 2 IH
Eight times/year more
85
96
89
04
05
92
04
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1986-2003 (18 Years)
Major Hurricanes 3 or 0.18/year
2004-2005 (2 Years)
Major Hurricanes 4 or 2/year
Twelve times/year more
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GLOBE COOLING
ATLANTIC THC STRONG
CAT 3-4-5 TRACKS
GLOBE WARMING
ATLANTIC THC WEAK
CAT 3-4-5 TRACKS
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1925-1965 41YEARS 24 IH
1966-2006 41YEARS 7 IH
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38
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0.17/year
0.59/year
44
33
85
54
55
54
96
60
59
89
28
04
49
33
47
50
26
45
05
65
92
48
04
44
50
29
60
35
? as frequent
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US Landfalling Major Hurricanes
CO2
0.95 year
365 ppm
0.54 year
310 ppm
39 Landfalls
22 Landfalls
Background 280 ppm
zero
1925-1965 41 Years
1966-2006 41 Years
2050
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US Landfalling tropical cyclones by intensity
during two 50-year periods
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2005 Hurricane Season
Open Atlantic Ocean Differences
1933 Hurricane Season
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A Typical Day in 2007 Marine Data Available
around 12 UTC
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A Typical Day in 1907 Marine Data Available
around 12 UTC
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• Recently-Published Paper
• Trends in Global Tropical Cyclone Activity over
  the Past Twenty Years (1986-2005)
• By Klotzbach, P. J., 2006 Geophysical Research
  Letters, 33, L10805.

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Category 4-5 Hurricanes by Ten-Year Periods
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Figure 4 From Webster et al. (2005)
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Correlation between Boreal Summer Basin-wide Sea
Surface Temperatures and Tropical Cyclone
Activity (1986-2005)
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Klotzbach (2006)
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Kossin et al. (2007)
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Summary

• Tropical sea surface temperatures have warmed
  about 0.2 - 0.3C over the past twenty years
• Little trend in Category 4-5 hurricanes has been
  seen since 1990
• Global Accumulated Cyclone Energy (ACE) has
  actually decreased slightly from 1990-2005
• Other factors besides sea surface temperatures
  clearly play a role in seasonal variability of
  tropical cyclone activity and intensity

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Questions???