Increased rainfall to alleviate dryness in areas of West Africa and Central America
Africa Weather Hazards
Despite increased rainfall over some areas of the Gulf of Guinea over the past fews weeks, low and erratic rainfall in April and May has led to growing moisture deficits over Liberia and parts of Sierra Leone.
Low and infrequent rainfall since late March has resulted in drought across parts of southeastern Kenya and northeastern Tanzania. The potential for recovery remains unlikely as below-average rain is forecast during the next week for coastal regions, and areas inland are now climatologically dry.
Below-normal rain in most regions
Rainfall was below average throughout the region during the past 7 days.
Many areas recorded rainfall deficits between 10-50mm, while some areas received less than 10mm of total rainfall (Figure 1). A few local areas received heavier, and even above-average, amounts of rain, including parts of Sierra Leone, western Guinea, central Mali, and southern Nigeria. Already-dry portions of far western Africa such as Liberia and parts of Sierra Leone remained abnormally dry, with the exception of northern Sierra Leone.
This past week’s limited rain has begun to broaden the region of significant moisture deficits.
An analysis of the cumulative rainfall during the last 90 days indicates a favorable rainfall performance across much of central Gulf of Guinea, with higher rainfall percentile rankings (> 70%) over portions of Burkina Faso, Mali, Niger, Ghana, Togo, and Benin (Figure 2). This was due to a surge in on-shore, southerly flow, bringing moisture and inducing weather disturbances within the region. In contrast, very low percentile rankings (< 10%), indicating that the past month has been among the driest in record, are observed across Liberia, portions of Sierra Leone, and localized areas of Guinea, and southern Togo. Southern portions of Nigeria register similar percentile rankings. The drier than average conditions over areas of Liberia and Sierra Leone are attributed to an extremely poor and erratic start to the rainfall season since mid-April.
During the upcoming week, model forecasts suggest that rains will increase for the eastern part of the Gulf of Guinea region. Rainfall amounts could exceed 100mm in parts of Nigeria. More seasonable, but still substantial rainfall totals are to be expected in far western portions of the region, which could favorably impact areas of abnormal dryness.