Performance of seasonal rainfall forecasts in Malawi

Abstract

This research evaluates the performance of seasonal rainfall forecasts in Malawi, which has consistently been issued since 2003. The main predictor indices are the El Nino southern oscillation (ENSO). While in some years the rainfall association has been observed to be in the predicted category, in some years the outcome has been on the contrary. However no comprehensive studies have been carried out to assess the success. The objective of this study was to determine the skill of the forecast and also evaluate the suitability of the ENSO as predictor of seasonal rainfall over Malawi. The forecast seasonal rainfall in Malawi generally did not perform well in terms of discrimination of events. Nonetheless it was observed that while the overall score over the years is low over the northern region, it was average over the southern region. The low skill in forecast over the northern part was attributed to the week relationship between ENSO and rainfall over the region. ENSO is positively correlated with the equatorial region and negatively correlated with the sub-tropical regions, however the northern part of Malawi is in the transition zone. It is therefore recommended that further Research be conducted to identify other suitable predictors rather than depending on ENSO alone.