Mesoγ-scale distribution of orographic precipitation: numerical study and comparison with precipitation derived from radar measurements

On the assumption that moisture convergence due to mechanical uplifting approximately equals the orographic precipitation, the mesoγ-scale rainfall distributions over mountainous regions in Israel are investigated. The simulated distributions are compared to rainfall observations both from raingages and from radar reflectivities. The mean error in the predicted rainfall on scale of 2 km was ±8.4% for mean annual normals and 15%-20% for three case studies. It is suggested that orographic rainfall on the small mesoscale is highly predictable with the adiabatic assumption that the uplifting is determined by V.∇Z_s, where V is the horizontal wind encountering the mountain and Z_s is the topographic elevation. -from Authors