The first episodes of floods caused by heavy rainfall during the major rainy season in 2018 occurred in Accra (5.6°N and 0.17°W), a coastal town, and Kumasi (6.72°N and 1.6°W) in the forest region on the 18th and 28th of June, respectively. We applied the Weather Research and Forecasting (WRF) model to investigate and examine the meteorological dynamics, which resulted in the extreme rainfall and floods that caused 14 deaths, 34076 people being displaced with damaged properties, and economic loss estimated at $168,289 for the two cities according to the National Disaster Management Organization (NADMO). The slow-moving thunderstorms lasted for about 8 hours due to the weak African Easterly Wave (AEW) and Tropical Easterly Jet (TEJ). Results from the analysis showed that surface pressures were low with significant amount of moisture influx aiding the thunderstorms intensification, which produced 90.1 mm and 114.6 mm of rainfall over Accra and Kumasi, respectively. We compared the rainfall amount from this event to the historical rainfall data to investigate possible changes in rainfall intensities over time. A time series of annual daily maximum rainfall (ADMR) showed an increasing trend with a slope of 0.45 over Accra and a decreasing trend and a slope of –0.07 over Kumasi. The 95th percentile frequencies of extreme rainfall with thresholds of 45.10 mm and 42.16 mm were analyzed for Accra and Kumasi, respectively, based on the normal distribution of rainfall. Accra showed fewer days with more heavy rainfall, while Kumasi showed more days with less heavy rainfalls.

中文翻译：

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加纳洪水的气象分析

在2018年的主要雨季，由强降雨引起的洪水的首发发生在沿海城镇阿克拉（5.6°N和0.17°W），以及该地区森林地区的库马西（6.72°N和1.6°W）。 6月18日和28日。我们应用天气研究和预报（WRF）模型调查和检查了气象动态，结果导致极端降雨和洪水导致14人死亡，34076人因财产受损而流离失所，两个城市的经济损失估计为168,289美元根据国家灾难管理组织（NADMO）的说法。由于弱的非洲东风（AEW）和热带东风急流（TEJ），缓慢移动的雷暴持续了大约8小时。分析结果表明，地表压力很低，大量的水分涌入有助于雷暴的加剧，在阿克拉和库马西分别产生了90.1 mm和114.6 mm的降雨。我们将该事件的降雨量与历史降雨数据进行了比较，以调查降雨强度随时间可能发生的变化。年日最大降雨量（ADMR）的时间序列显示出增加的趋势，阿克拉地区的坡度为0.45，而库马西地区的坡度为–0.07，呈下降趋势。根据降雨量的正态分布，分别对阿克拉和库马西的极端降雨的第95个百分率频率进行了分析，其阈值分别为45.10 mm和42.16 mm。阿克拉的降雨量少的日子少，而库玛西的降雨量少的日子多。