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.

Top 10 August

Hindcasts (1900-2005)

Bottom 10 August

Hindcasts (1900-2005)

HURRICANE TRACKS

HURRICANE TRACKS

49.75 Hurricane

Days

1.75 Hurricane

Days

Top 5 June Forecasts

(1984-2008)

Bottom 5 June

Forecasts (1984-2008)

28.25 Hurricane

Days

3.25 Hurricane

Days

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., 50-Year 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%

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 – Ranked by Observed 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 Activity – Based on August Hindcast NTC (1900-2007)

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%)

Caribbean Probability – Based on Poisson Distribution

1860 1900 1940 1980 2020

Goldenberg et al. (2001)

ATLANTIC

THC

STRONG

ATLANTIC

THC

WEAK

POSITIVE AMO

NEGATIVEAMO

CAT 3-4-5 TRACKS

CAT 3-4-5 TRACKS

79 Years

78 Years

86 Major Hurricane

Days

30 Major Hurricane

Days

Caribbean ACE - Based on TC Maximum Intensity in the Caribbean

93

176

136

195

115

319

0

50

100

150

200

250

300

350

1851-1877 1878-1899 1900-1925 1926-1969 1970-1994 1995-2008

Positive AMO

Negative AMO

Puerto Rico (Within 50 Miles) ACE

20

29

14

24

11

33

0

5

10

15

20

25

30

35

1851-1877 1878-1899 1900-1925 1926-1969 1970-1994 1995-2007

Positive AMO

Negative AMO

TEN COLDEST ASO NINO 3.4 (1900-

2008)

TEN WARMEST ASO NINO 3.4 (1900-

2008)

56.75 Hurricane

Days

5.5 Hurricane

Days

TWENTY COLDEST ASO NINO 3.4 (1900-

2008)

TWENTY WARMEST ASO NINO 3.4 (1900-

2008)

105.5 Hurricane

Days

28.5 Hurricane

Days

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

Caribbean Activity – Based on ASO Nino 3.4 (1900-2007)

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.”