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Sub-seasonal forecasts provide forecast information on the 1-4 week timescale and are produced by a number of global weather forecast providers, including the European Centre for Medium-Range Weather Forecasts (ECMWF). The development and application of new sub-seasonal forecasting products in the agricultural sectors of Ghana and Kenya are described. Using a co-production approach transforms the role of the forecast user from merely a recipient of forecast information to being involved in the forecast product development process. Experiences of co-producing sub-seasonal forecast products for agricultural application in Kenya and Ghana. [Extracted from the article]

Understanding the environmental evolution of mesoscale convective systems (MCSs) is critical for forecasting weather in West Africa. This study investigated the thermodynamic and synoptic environments of MCSs over West Africa on 26 (storm 1) and 28 (storm 2) June 2018. Primary datasets used to assess the diurnal evolution of the storms were obtained from ERA5. The results showed a trapped gravity wave, enhanced by a well‐established African Easterly Jet and monsoon trough, was responsible for the initiation of storm 1. Both storms also initiated in the presence of several moist lower (925–850 hPa) to mid‐tropospheric (600 hPa) cyclonic and anticyclonic vortices, controlling inland moisture advection. The lower troposphere was moistened through moisture advection by the West African westerly jet for storm 1 and the nocturnal low‐level jet prior to initiation for storm 2. For both storms, the evolution of outgoing longwave radiation showed a consistent atmosphere of deep afternoon convection. Boundary layer height increased significantly during storm evolution to support the increasing ascent of warm air. Vegetation cover differences may have also likely aided the evolution of storm 2. The passage of gravity waves from decaying storms can aid forecasters to nowcast likely regions of afternoon convection with high accuracy. Under the GCRF African Science for Weather Information and Forecasting Techniques (SWIFT), these findings are crucial in fulfilling the project's aims of improving weather forecasting capability and communication over West Africa. [ABSTRACT FROM AUTHOR]