Transcript Caribbean/Central American Hurricane Landfall Probabilities Phil Klotzbach Department of Atmospheric Science Colorado State University Climate Diagnostics and Prediction Workshop October 27, 2009

Caribbean/Central American Hurricane Landfall
Probabilities
Phil Klotzbach
Department of Atmospheric Science
Colorado State University
Climate Diagnostics and Prediction Workshop
October 27, 2009
Basic Premise:
Caribbean and Central American
hurricane activity is related to Atlantic
basin seasonal hurricane forecasts.
More active tropical cyclone seasons
as predicted by the Tropical
Meteorology Project (CSU) tend to have
more landfalling hurricanes.
49.75
Hurricane
Days
Top 10 August
Hindcasts (19002005)
HURRICANE
TRACKS
1.75
Hurricane
Days
HURRICANE
TRACKS
Bottom 10 August
Hindcasts (1900-2005)
28.25
Hurricane
Days
3.25
Hurricane
Days
Top 5 June
Forecasts (19842008)
Bottom 5 June
Forecasts (1984-2008)
Caribbean/Central America
Probabilities
Climatological and current-year
probabilities of a named storm,
hurricane and major hurricane
within 50 miles and 100 miles of
each island or landmass
50-Year Probabilities
Historical Probability Calculation Steps
- Select all tropical cyclones that tracked within 50 and 100 miles of each
island or landmass during the 20th century
- Assign the maximum intensity of the tropical cyclone that was reached
within 50 or 100 miles of the landmass
- Calculate climatological probabilities using the Poisson distribution (e.g.,
EP = px/epx!) where
EP = Expected Probability
p = Annual average number of tropical cyclones that have occurred in
the 20th century
x = Number of storms expected in the upcoming year based on the
Poisson formula
- For Barbados, 26 named storms tracked within 50 miles of Barbados
during the 20th century, and therefore, the Poisson distribution gives the
climatological probability of one or more named storms making landfall as
23%
50 Miles
100 Miles
Current-Year Probability Calculations
- Multiply the historical number of storms that occurred over the 20th century
by predicted Net Tropical Cyclone activity (where 100% is defined to be an
average season)
-For example, for Barbados, if 26 named storms formed during the 20th century
and the predicted NTC was 150%, the current-year probability would be calculated
based on 39 named storms (32%)
- Apply the Poisson distribution to this new number of storms
50-Year Probability Calculations
- Apply the binomial distribution to the annual-average probabilities (e.g., 50Year Prob. = 1 - (1 - One-Year Prob.)50
- For example, if the individual-year probability is 2%, the 50-year
probability would be: 50-Year Prob. = 1 - (1 – 0.02)50 = 63%
Current Year and Climatological Probabilities
(1900-2000)
Country
NS Prob.
(50 Miles)
H Prob.
(50 Miles)
MH Prob.
(50 Miles)
The Bahamas
66% (72%) 40% (45%) 21% (24%)
Cuba
64% (70%) 39% (44%) 19% (22%)
Haiti
33% (38%) 18% (21%)
8% (9%)
Jamaica
32% (37%) 15% (17%)
6% (7%)
Mexico
72% (78%) 39% (44%) 13% (15%)
Nicaragua
24% (27%) 10% (11%)
5% (6%)
Puerto Rico
29% (33%) 13% (15%)
4% (5%)
Climatological probabilities are in parentheses
50-Year Probabilities
Country
MH Prob.
(50 Miles)
The Bahamas
>99%
Cuba
>99%
Haiti
99%
Jamaica
97%
Mexico
>99%
Nicaragua
95%
Puerto Rico
92%
Caribbean Activity – Ranked by
Observed NTC (1900-2007)
Years (Ranked by NTC)
Named
Storms
Hurricanes
Major Hurricanes
Most Active 27 Years
135
77
38
Years 28-55
97
41
15
Years 57-82
65
26
8
Least Active 27 Years
48
10
3
Caribbean Activity – Based on August
Hindcast NTC (1900-2007)
Years (Ranked by NTC)
Named
Storms
Hurricanes
Major Hurricanes
Most Active 27 Years
134
70
32
Years 28-55
102
43
15
Years 57-82
64
28
12
Least Active 27 Years
41
12
5
Caribbean Probability – Based on Poisson Distribution
Observed (Hindcast)
Named
Storms
Hurricanes
Major Hurricanes
Most Active 27 Years
99% (99%)
94% (93%)
76% (69%)
Years 28-55
97% (98%)
78% (80%)
43% (43%)
Years 57-82
91% (91%)
62% (65%)
26% (36%)
Least Active 27 Years
83% (78%)
31% (36%)
11% (17%)
1860
1900
1940
Goldenberg et al. (2001)
1980
2020
86 Major
Hurricane
Days
79 Years
POSITIVE AMO
ATLANTIC
THC
CAT 3-4-5
TRACKS
STRONG
30 Major
Hurricane
Days
NEGATIVEAMO
78 Years
ATLANTIC
THC
CAT 3-4-5
TRACKS
WEAK
Caribbean ACE - Based on TC Maximum Intensity in the
Caribbean
350
Positive AMO
300
319
Negative AMO
250
195
200
176
150
136
115
100
93
50
0
1851-1877
1878-1899
1900-1925
1926-1969
1970-1994
1995-2008
Puerto Rico (Within 50 Miles) ACE
35
Positive AMO
29
30
Negative AMO
24
25
20
33
20
14
15
11
10
5
0
1851-1877
1878-1899
1900-1925
1926-1969
1970-1994
1995-2007
56.75
Hurricane
Days
TEN COLDEST
ASO NINO 3.4
(1900-2008)
5.5
Hurricane
Days
TEN WARMEST
ASO NINO 3.4
(1900-2008)
105.5
Hurricane
Days
TWENTY
COLDEST ASO
NINO 3.4 (19002008)
28.5
Hurricane
Days
TWENTY
WARMEST ASO
NINO 3.4 (19002008)
Caribbean Activity – Based on ASO
Nino 3.4 (1900-2007)
Years (Ranked by ASO
Nino 3.4)
Named
Storms
Hurricanes
Major Hurricanes
Coolest 27 Years
124
59
24
Years 28-55
85
40
14
Years 57-82
86
34
17
Warmest 27 Years
49
20
9
Future Work
- Investigate precursor steering current
patterns for Caribbean/Central American
landfall
- Create shorter period user-selected
probabilities for landfall using climatological
storm frequency in the Caribbean/Central
America
Arago’s 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.”