Predictability of Ethiopian Kiremt rainfall (June to September: JJAS) and forecast skill of the European Centre for Medium-Range Weather Forecasts (ECMWF) fifth-generation seasonal forecast system 5 (SEAS5) is explored during 1981–2019. The first empirical orthogonal function of observed rainfall explains 50.6% of the total variability and is characterized by positive rainfall anomalies largely confined over the northwestern and central-western regions of Ethiopia. Consequently, a Kiremt rainfall index (KRI) is defined for this region. The correlation coefficient (CC) between the observed and predicted KRI is 0.68 and 0.53 for May and April starts, respectively. Composite analysis of sea surface temperature (SST) and lower-level circulation based on excess and deficit years of Kiremt rains shows that the El Niño Southern–Oscillation is the main modulator of the Kiremt rainfall variability. The CC between KRI and Niño3.4 index is − 0.62, indicating that El Niño is accompanied by below-normal Kiremt rainfall, while La Niña is accompanied by above-normal amounts. The fifth generation of ECMWF atmospheric reanalysis (ERA5) shows that excess (deficit) Kiremt rainfall anomalies are associated with an anomalous low (high) pressure centered over northeast Arabian Peninsula and an anomalous in-phase (reverse) low-level Somali Jet. SEAS5 reproduces the spatial and temporal components of observed Kiremt rainfall variability, including the main climatic features associated with excess and deficit Kiremt rainfall in May and April starts. However, certain important observed features like above-normal SSTs in the Gulf of Guinea are not well predicted. Results indicate that Kiremt rains has some potential predictability and SEAS5 shows a moderate forecast skill. Probabilistic analysis shows highest values where predictability and deterministic skill are also highest.

在 1981-2019 年期间探索了埃塞俄比亚基雷姆特降雨的可预测性（6 月至 9 月：JJAS）和欧洲中期天气预报中心 (ECMWF) 第五代季节性预报系统 5 (SEAS5) 的预报技巧。观测到的降雨量的第一个经验正交函数解释了总变率的 50.6%，其特点是降雨量正异常，主要局限在埃塞俄比亚的西北部和中西部地区。因此，为该地区定义了基雷姆特降雨指数 (KRI)。5 月和 4 月开始时，观察到的和预测的 KRI 之间的相关系数 (CC) 分别为 0.68 和 0.53。基于基里姆特降雨的过剩年和亏缺年的海面温度（SST）和低层环流的综合分析表明，厄尔尼诺南方涛动是基里姆特降雨变化的主要调节因素。KRI和Niño3.4指数之间的CC为-0.62，表明厄尔尼诺伴随着低于正常的基雷姆特降雨，而拉尼娜则伴随着高于正常的降雨量。第五代 ECMWF 大气再分析 (ERA5) 显示，过量（亏缺）Kiremt 降雨异常与以阿拉伯半岛东北部为中心的异常低（高）压和异常同相（反向）低空索马里急流有关。SEAS5 再现了观测到的基雷姆特降雨变化的空间和时间分量，包括与 5 月和 4 月开始的基雷姆特降雨过多和不足相关的主要气候特征。然而，某些重要的观测特征，如几内亚湾高于正常水平的海温并没有得到很好的预测。结果表明基里姆特降雨具有一定的潜在可预测性，而 SEAS5 显示出中等的预测能力。概率分析显示最高值，其中可预测性和确定性技能也最高。