Farmers’ first rain: investigating dry season rainfall characteristics in the Peruvian Andes

Abstract In the Peruvian Andes, first light rainfalls towards end of dry season in August-September are known as pushpa . Softening soils and improving sowing conditions, these rains crucial for planting dates agricultural planning. Yet remains to date unexplored literature. This study uses observations convection-permitting model simulations describe characteristics Rio Santa valley (Peru). Comparing an observed case August 2018 with a wet event same season, we find coincide upper-level westerly winds that otherwise characteristic periods. These conditions impose layer favours small-scale, vertically-capped convection, explaining low rainfall intensities reportedly typical Climatologically, 83% -type events occur under winds, dominating August, when 60% modelled spatial extent is linked Larger, more intense deep-convective gradually increase alongside easterly September, causing relative cloud coverage drop ̃20%. We note high inter-annual -decadal variability this balance between convective types, being twice during 2000-2009 than 2010-2018 decade over key period. result may explain farmers’ perception valley, who recently reported increased challenges due delayed but before rainy start. thus conclude germination crucially affected by rain, resulting higher probability late be intense.