Abstract:
The world climate is changing and sub-Saharan Africa experiences it through
climate variability. Since the majority of people in the region depend on
agriculture for their livelihood, the predictability of rainfall is very critical in
reducing their vulnerability and seizing opportunities. This study aimed at
verifying skill and usefulness of the forecasts from two drought monitoring
centres-GHACOF and SARCOF-by looking at accuracy, bias and skill in 16
synoptic stations in Tanzania. The results have indicated that seasonal
forecasts by the two centres have similar patterns of accuracy. Both have better
accuracy in the northern parts of Tanzania compared to the southern parts
during October·November-December (OND) period. During January-February-
March for SARCOF and March·April·May for GHACOF forecasts show better
accuracy indices in the southern parts compared to the northern parts of the
country. The usefulness of both forecasts is still very low because the accuracy
levels are below 0.8. The forecasts are not showing much bias, i.e., they are not
over· or under· forecast rainfall amounts. However, the forecasting skill for both
centres is very low (majority of stations with HSS < 0.2). This study
recommends the two centres, together with national meteorological services, to
improve accuracy and skill of seasonal rainfall forecasts. The seasonal forecasts
should be disseminated widely to users, including farmers. However, a caution
should be provided to farmers as the accuracies of the seasonal forecasts are
seasonal, location and forecast dependent.
