Tables

Table 1. Summary of statistics for Atlantic tropical cyclones and West African rainfall for 1950-1990. The numbered columns show yearly incidence of 1) named storms (NS), 2) named storm days (NSD), 3) hurricane days (HD), 5) intense or category 3-4-5 hurricanes (IH) (Simpson 1974), 6) intense of category 3-4-5 hurricane (IHD), 7) hurricane destruction potential (HDP), 8) precipitation anomal expressed as standardized deviations for previous year August-November Gulf of Guinea (RG) and 9) August-September precipitation in the western Sahel (RS) of the previous year. An expanded discussion of these hurricane parameters is given in appendix A.
 
  

  NS NSD H HD IH IHD HDP RG RS
Year 1 2 3 4 5 6 7 8 9 Year
1950 13 98 11 60 8 18.75 213 1.07 -0.14 1950
1951 10 58 8 36 5 8.25 120 -0.66 1.68 1951
1952 7 40 6 23 3 6.75 73 0.65 0.49 1952
1953 14 64 6 18 4 6.75 61 0.41 0.93 1953
1954 11 44 8 32 2 9.50 99 -0.16 0.20 1954
1955 12 82 9 47 6 17.25 171 0.64 0.60 1955
1956 8 30 4 13 2 2.75 40 0.41 1.00 1956
1957 8 38 3 21 2 6.50 71 -0.36 0.47 1957
1958 10 56 7 30 5 9.50 100 1.03 0.58 1958
1959 11 41 7 22 2 4.25 63 -0.74 1.45 1959
1960 7 30 4 18 2 11.00 80 0.12 0.25 1960
1961 11 71 8 48 7 24.50 183 1.05 0.23 1961
1962 5 22 3 11 1 0.50 26 -0.74 0.48 1962
1963 9 52 7 37 2 7.00 111 0.73 0.28 1963
1964 12 71 6 43 6 14.75 149 1.18 -0.12 1964
1965 6 40 4 27 1 7.50 78 -0.68 0.59 1965
1966 11 62 7 42 3 8.75 126 -0.17 0.75 1966
1967 8 58 6 36 1 5.75 102 -0.14 0.34 1967
1968 7 26 4 10 0 0.00 21 -0.51 0.72 1968
1969 17 84 12 40 5 6.75 114 1.28 -0.83 1969
1970 10 24 5 7 2 1.00 18 -0.31 0.38 1970
1971 13 63 6 29 1 1.00 65 -0.23 0.45 1971
1972 4 21 3 6 0 0.00 14 -0.40 -0.19 1972
1973 7 33 4 10 1 0.25 24 -0.88 -1.10 1973
1974 7 32 4 14 2 4.25 46 0.43 -0.72 1974
81975 8 43 6 20 3 2.25 54 -0.08 -0.04 1975
1976 8 45 6 26 2 1.00 18 -0.59 -0.50 1977
1977 6 14 5 7 1 1.00 18 -0.59 -0.50 1977
1978 11 40 5 14 2 3.50 40 -0.50 -0.75 1978
1979 8 44 5 22 2 5.75 73 -0.73 -0.36 1979
1980 11 60 9 38 2 7.25 126 0.55 -0.92 1980
1981 11 61 7 22 3 3.75 63 0.36 -0.34 1981
1982 5 16 2 6 1 1.25 18 -0.93 -0.44 1982
1983 4 14 3 4 1 0.25 8 -0.61 -0.90 1983
1984 12 51 5 18 1 0.75 42 -1.32 -1.24 1984
1985 11 51 7 21 3 4.00 61 0.04 -1.23 1985
1986 6 23 4 10 0 0.00 23 0.13 -0.51 1986
1987 7 37 3 5 1 0.50 11 -0.48 -0.01 1987
1988 12 47 5 24 3 8.00 81 1.37 -0.63 1988
1989 11 66 7 32 2 10.75 108 0.35 0.29 1989
1990 14 68 8 27 1 1.00 57 0.19 0.10 1990
Mean 9.34 46.83 5.83 23.80 2.46 5.71 73.56
S.D. 2.98 20.03 2.21 13.62 1.90 5.60 49.29
Coef. of  Var 0.32 0.43 0.38 0.57 0.77 0.98 0.67
 

Table 2. Comparison of average seasonal hurricane activity in the 15 yr when the 10-month extrapolated sum of the September 50-mb QBO zonal wind near 10°N plus absolute values of the zonal wind shear to 30 mb was the lowest (westerly QBO phase) versus those 15 yr when this sum was the highest (easterly QBO phase) for the years 1950-1990.
  

 
[U50-  {U50-U30}]
  
Lowest 
15 yr 
westerly 
phase 
Lowest 
15 yr 
easterly 
phase 
Ratio 
lowest/highest 
values 
No. of hurricanes 7.07 4.80 1.47
No. of hurricanes days 32.27 16.40 1.97
No. of intense hurricanes 3.53 1.67 2.12
No. of intense-hurricanes days 8.30 2.97 2.80

Table 3.) Listing of months into westerly or easterly phase of each November period between 1950 and 1990 with next September year of application.
 
50 mb (20 km) 
30 mb (23km)
Year of 
November 
determination 
Months
since first 
westerly 
Months since first
easterly 
Year of September Application
Year of 
November 
determination 
Months
since first 
westerly 
Months since first
easterly 
Year of September Application
1949*
  
6
----> 1950
1949*
  
8
----> 1950
1950
3
  
---> 1951
1950
4
  
---> 1950
1951
16
  
---> 1952
1951
  
3
--->1952
1952
  
10
---> 1953
1952
5
  
---> 1953
1953
12
  
---> 1954
1953
  
1
---> 1954
1954
  
9
---> 1955
1954
1
  
---> 1955
1955
9
  
---> 1956
1955
13
  
---> 1956
1956
  
7
---> 1957
1956
  
8
---> 1957
1957
6
  
---> 1958
1957
8
  
---> 1958
1958
  
4
---> 1959
1958
  
7
---> 1959
1959
4
  
---> 1960
1959
6
  
---> 1960
1960
  
6
---> 1961
1960
  
8
---> 1961
1961
6
  
---> 1962
1961
11
  
---> 1962
1962
  
2
---> 1963
1962
  
8
---> 1963
1963
3
  
---> 1964
1963
5
  
---> 1964
1964
15
  
---> 1965
1964
16
  
---> 1965
1965
  
4
---> 1966
1965
  
12
---> 1966
1966
5
  
---> 1967
1966
7
  
---> 1967
1967
7
  
---> 1968
1967
  
5
---> 1968
1968
  
9
--->1969
1968
  
16
---> 1969
1969
6
  
--->1970
1969
9
  
---> 1970
1970
  
6
--->1971
1970
  
11
---> 1971
1971
5
  
--->1972
1971
10
  
---> 1972
1972
  
5
--->1973
1972
  
7
---> 1973
1973
7
  
--->1974
1973
11
  
---> 1974
1974
  
5
--->1975
1974
  
11
---> 1975
1975
4
  
--->1976
1975
6
  
---> 1976
1976
  
1
--->1977
1976
  
4
---> 1977
1977
  
13
--->1978
1977
3
  
---> 1978
1978
9
  
--->1979
1978
  
0
---> 1979
1979
  
5
--->1980
1979
  
10
---> 1980
1980
5
  
--->1981
1980
9
  
---> 1981
1981
  
1
--->1982
1981
  
7
---> 1982
1982
1
  
--->1983
1982
4
  
---> 1983
1983
14
  
--->1984
1983
  
5
---> 1984
1984
  
7
--->1985
1984
  
16
---> 1985
1985
6
  
--->1986
1985
12
  
---> 1986
1986
  
1
--->1987
1986
  
6
---> 1987
1987
2
  
--->1988
1987
4
  
---> 1988
1988
14
  
--->1989
1988
16
  
---> 1989
1989
  
6
--->1990
1989
  
10
---> 1990
1990
6
  
--->1991
1990
9
  
---> 1991


 

Table 4.) September forecast QBO wind at 10N latitude from previous November as a function of the number of months to November that change to westerly (left side) or easterly (right side) relative wind has occurred.
 
 
 
 
50 mb (20 km) 
  
Months since
change to
westerly of
November wind
10-month
September 
forecast
(m s-1)
Months since 
change to 
easterly of
November wind
10-month 
September
forecast
(m s-1)
0 -1 0 -22
1 -2 1 -21
2 -3 2 -17
3 -4 3 -14
4 -6 4 -9
5 -8 5 -5
6 -12 6 -3
7 -14 7 -2
8 -17 8 -1
9 -19 9 0
10 -20 10 0
11 -22 11 -1
12 -23 12 -1
13 -23 13 -2
14 -23 14 -2
15 -23 15 -3
16 -23 16 -4
17 -23 17 -6
18 -23
30 mb (23km) 
0 -3 0 -32
1 -4 1 -32
2 -5 2 -30
3 -9 3 -26
4 -13 4 -24
5 -18 5 -14
6 -21 6 -9
7 -25 7 -5
8 -28 8 -3
9 -30 9 -1
10 -31 10 -1
11 -32 11 -2
12 -32 12 -2
13 -32 13 -3
14 -32 14 -5
15 -32 15 -7
16 -32 16 -9
17 -32 17 -11
18 -32

 

Table 5.) Comparison of November-September ten-month extrapolated (forecast) QBO zonal winds versus actual (observed) September winds. Positive forecast errors indicate an overestimation of the zonal winds; negative, an underestimate. (Values in m s-1)
 
50 mb (20 km) 
30 mb (23km) 
Year 
Forecast September 
wind
Observed 
September 
wind
Forecast 
error
Forecast September 
wind
Observed 
September 
wind
Forecast 
error
1950
-3
-3
0
-3
-2
-1
1951
-4
-8
4
-13
-19
6
1952
-23
-19
-4
-26
-8
-18
1953
0
-5
5
-18
-13
-5
1954
-23
-23
0
-32
-25
-7
1955
0
0
0
-4
-4
0
1956
-19
-18
-1
-33
-29
-4
1957
-2
-2
0
-3
-10
7
1958
-12
-14
2
-28
-30
2
1959
-9
0
-9
-5
1
-6
1960
-6
-15
9
-21
-26
5
1961
-3
-2
-1
-3
-4
1
1962
-12
-10
-2
-32
-27
-5
1963
-17
-8
-9
-3
-8
5
1964
-4
1
-5
-18
-11
-7
1965
-23
-16
-7
-32
-31
-1
1966
-9
-4
-5
-2
-2
0
1967
-8
-6
-2
-25
-17
-8
1968
-23
-20
-3
-14
-31
17
1969
0
-3
3
-9
-6
-3
1970
-12
-21
9
-30
-31
1
1971
-3
-3
0
-2
-10
8
1972
-8
-19
11
-31
-28
-3
1973
-5
-4
-1
-5
-10
5
1974
-14
-18
4
-32
-31
-1
1975
-5
-5
0
-2
-3
1
1976
-6
-7
1
-21
-21
0
1977
-21
-23
2
-24
-11
-13
1978
-2
-1
-1
-9
-12
3
1979
-19
-17
-2
-31
-29
-2
1980
-5
-2
-3
-1
-2
1
1981
-8
-8
0
-30
-26
-4
1982
-21
-15
-6
-5
-1
-4
1983
-2
-6
4
-13
-23
10
1984
-23
-26
3
-14
-32
18
1985
-2
1
-3
-9
-3
-6
1986
-12
-8
-4
-32
-23
-9
1985
-2
1
-3
-9
-3
-6
1984
-23
-26
3
-14
-32
18
1985
-2
1
-3
-9
-3
-6
1986
-12
-8
-4
-32
-23
-9
1987
-21
-14
-7
-9
3
-12
1988
-3
-4
1
-13
-17
4
1989
-23
-18
-5
-32
-29
-3
1990
-3
-6
2
-1
-6
5

 
 

  Table 6.) Comparison of average hurricane activity in the hurricane seasons a year each of the ten wettest western Sahel (Fig 6) August-September periods versus the ten seasons a year after each of the ten driest periods 1949 and 1989.
 
 
Ten Wettest
Ten driest
Ratio
No. of hurricanes 
6.2
5.8
1.07
No. of hurricanes days
26.8
19.3
1.39
No. of intense hurricanes 
3.1
2.0
1.55
No. of intense hurricanes days
7.2
3.6
1.99

 
 
 


 

Table 7.) Comparison of average hurricane activity in the seasons follwing the ten wettest August to November periods along the Gulf of Guinea versus the ten driest periods for the year 1949-1989.
 
 
 
Ten Wettest
Ten driest
Ratio
No. of hurricanes 
8.0
4.6
1.74
No. of hurricanes days
39.0
17.7
2.20
No. of intense hurricanes 
4.7
1.8
2.61
No. of intense hurricanes days
12.0
2.9
4.16

 


 

Table 8.) Empirical weights for composite functions of wind and raindall from a jackknife solution.
 
 
 
Wind
Rainfall
a1
a2
a3
a4
a5
Named storms 1.000 0.252 -0.640 1.000 2.498
Named storms days 1.000 0.424 -0.316 1.000 2.390
Hurricanes 1.000 -0.320 -3.384 1.000 2.390
Hurricanes days 1.000 1.781 -1.370 1.000 2.302
Intense hurricanes 1.000 0.103 -1.415 1.000 2.144
Intense hurricanes days 1.000 -0.080 -1.410 1.000 2.292
Hurricane destruction potential 1.000 1.066 -1.346 1.000 1.700

 
 

Table 9.) Agreement coefficient (), probability (P), and r2 values from a jackknife solution.
 
 
 
P
r2
Named storms 0.440 0.22 x10-5 0.395
Named storms days 0.514 0.89 x 10-7 0.488
Hurricanes 0.447 0.15 x 10-5 0.466
Hurricanes days 0.491 0.46 x 10-6 0.511
Intense hurricanes 0.498 0.95 x 10-7 0.581
Intense hurricanes days 0.451 0.27 x 10-6 0.517
Hurricane destruction potential 0.447 0.11 x 10-5 0.527

 


 
 

Table 10.) Regression weight from a nonjackknife solution for prediction equations.
 
 
0
1
2
Named storms 11.732 0.135 0.701
Named storms days 64.072 1.031 7.149
Hurricanes 7.560 0.049 0.759
Hurricanes days 33.303 0.215 6.645
Intense hurricanes 3.571 0.042 0.717
Intense hurricanes days 7.605 0.124 2.006
Hurricane destruction potential 95.326 0.686 24.747