Modelling Convective Rainfall Processes Over the Jos Plateau Using the WRF Regional Climate Model

The Jos Plateau presents a compelling case for mesoscale meteorological investigation, with its complex orographic terrain generating unique convective rainfall processes poorly captured by global climate models. This study models convective rainfall over the Jos Plateau using the Weather Research and Forecasting (WRF) regional climate model, aiming to improve rainfall simulation skill in this topographically complex region. WRF version 4.3 was configured with a 4-kilometre inner domain driven by ERA5 reanalysis boundary conditions for five rainy seasons from 2019 to 2023. Four convective parameterization schemes were evaluated and performance assessed against gauge observations from nine NiMet stations. Results indicate that the Kain-Fritsch scheme best reproduces observed seasonal rainfall totals with a mean bias of minus 9 percent and correlation of 0.84 at monthly timescales. WRF significantly outperforms ERA5 in simulating the spatial gradient of orographic enhancement across the Plateau, reducing RMSE by 31 percent over the study domain. Analysis of simulated convective initiation timing confirms that afternoon heating of the Plateau surface is the dominant mechanism triggering localized convective storms, with maximum convective available potential energy values exceeding 2,800 J per kilogram on severe storm days. The study provides a validated regional modelling framework for future dynamical downscaling of climate projections over the Jos Plateau and recommends NiMet invest in operational WRF configuration for North Central Nigeria. Keywords: WRF, convective rainfall, Jos Plateau, regional climate model, orographic enhancement.