Ten driest years
|
Ranking of dry year
|
Standardized
deviation
of rainfall
|
Tropical
Storms
only
|
Minor
hurricanes
(Cat. 1-2)
|
Intense
hurricanes
(Cat.3-5)
|
Intense-hurricane
days
|
1984 (extremely dry)
|
-0.72
|
7
|
4
|
1
|
0.75
|
1983 |
-0.72
|
1
|
2
|
1
|
0.25
|
1977 |
-0.72
|
1
|
4
|
1
|
1.00
|
1972 |
-0.64
|
1
|
3
|
0
|
0.00
|
1973 |
-0.61
|
3
|
3
|
1
|
0.25
|
1986 |
-0.56
|
2
|
4
|
0
|
0.00
|
1982 |
-0.54
|
3
|
1
|
1
|
1.25
|
1987 |
-0.50
|
4
|
2
|
1
|
0.50
|
1976 |
-0.48
|
2
|
4
|
2
|
1.00
|
1980 (moderately dry) |
-0.46
|
2
|
7
|
2
|
7.25
|
Mean |
-0.64
|
2.6
|
3.4
|
1.0
|
1.23
|
Ten Wettest years
|
Ranking of dry year
|
Standardized
deviation
of rainfall
|
Tropical
Storms
only
|
Minor
hurricanes
(Cat. 1-2)
|
Intense
hurricanes
(Cat.3-5)
|
Intense-hurricane
days
|
1955 (extremely wet) |
1.20
|
3
|
3
|
6
|
17.25
|
1964 |
1.00
|
6
|
0
|
6
|
14.75
|
1961 |
0.94
|
3
|
1
|
7
|
24.50
|
1969 |
0.78
|
5
|
7
|
5
|
6.75
|
1953 |
0.73
|
8
|
2
|
4
|
6.75
|
1989 |
0.71
|
4
|
5
|
2
|
10.75
|
1952 |
0.62
|
1
|
3
|
3
|
6.75
|
1950 |
0.57
|
2
|
3
|
8
|
18.75
|
1958 |
0.55
|
3
|
2
|
5
|
9.50
|
1960 (moderately wet) |
0.55
|
3
|
2
|
2
|
11.00
|
|
___
|
_
|
_
|
_
|
_____
|
Mean |
0.76
|
3.8
|
2.8
|
4.8
|
12.72
|
Ratio wet/dry |
|
1.5/1
|
0.8/1
|
4.8/1
|
10.3/1
|
Table 3. Comparison of the early-season (i.e., prior to 1 August)
West African rainfall index for the ten driest and ten wettest seasons
during 1949-1990 versus the number of tropical storms (weaker than hurricane
force), minor (category 1 or 2) hurricanes, intense (category 3-5) hurricanes,
and intense-hurricane days. Early season rainfall includes Gulf of Guinea
rainfall for August through November during the previous year (weighted
0.3) and current year June-July western Sahel region rainfall (weighted
0.7).