In the past few years, significant progress has been made in terms of the improvement of numerical weather prediction models. It is proven that the enhancement of the model resolution increases the model quality.
In order to fulfil the lack of information in the field of forecast in Northern Cameroon, a very high-resolution version 3.7 of advanced research WRF (ARW) dynamical core for simulations with the National Centers for Environmental Prediction NCEP-GFS (spectral resolution about 12 km) with 64 vertical levels and sea surface temperature (SST) with 1° horizontal resolution have been implemented as boundary and initial conditions for operational forecast in the model.
The WRF model is run for 9 days and the output data is recorded every 3 hours. This work analyses simultaneously diurnal and daily simulate data from July, 14 to July, 23, 2018. WRF is being run at the Laboratory for Environmental Modelling of Atmospheric Physics (LEMAP) at the University of Yaoundé 1.
To validate the model forecast, the radiosoundings and very high resolution rainfall data ARC2 have been used in the present work within the same period for this purpose. These data combined in-situ measures and latest high quality research one provided by satellite (Mahakur et al. 2013). A detailed description of these data is provided in the next section.
In addition to radiosoundings and satellite data, re-analyses data have also been used to evaluate accurately the performance of the model. Thus, ERA5 wind and relative humidity database is used to further monitoring model forecast for the month of July 2018.
The diurnal and daily rainfall temporal series is calculated by adding 3 hourly data. The WRF model is initiated on 14, 18, 19, 20 and 22 July 2018 at 0000UTC, for day-9, day-5, day-3 and day-1 forecast lead times respectively. The spatial distribution of each parameter could be seen in different figures. The diurnal cycle of different parameters is computed for a 3-hour time series for the model output and also for the observation.
To improve the synoptic circulations, mesoscale features, and to capture heavy rainfall over Northern regions of Cameroon (Fig. 1), domain grids with a horizontal grid spacing of 12 km was provided.