Precipitation is one of the most complex and intermittent atmospheric processes, influenced by large-scale atmospheric circulation, weather-system characteristics, topography, land–atmosphere interactions, and moisture availability. This study investigates the potential influence of changes in Lake Jazmurian extent on the precipitation regime of its basin. Long-term precipitation records from 19 meteorological stations were analyzed using the Mann–Kendall test and Sen’s slope estimator to assess the temporal and spatial variability of precipitation. The synoptic mechanisms controlling precipitation were also examined under representative wet- and dry-season conditions in February and July 2019, respectively. Three scenarios, namely NOW, NORMAL, and EXTEND, were simulated using the WRF model. Model performance was evaluated by comparing simulated and observed precipitation using Bias, RMSE, and MAE.
The results revealed considerable spatial heterogeneity in precipitation trends across the basin, with no coherent and significant trend identified at the basin scale. Synoptic analysis indicated that winter precipitation is primarily associated with upper-level troughs, atmospheric ascent, and moisture transport from the Arabian Sea and Gulf of Oman. In summer, atmospheric conditions are generally dominated by the subtropical high-pressure system and associated subsidence, although limited monsoonal moisture occasionally affects the eastern part of the basin. The WRF model reproduced the timing and spatial distribution of major precipitation events with acceptable accuracy. Comparisons among the three lake-extent scenarios showed only minor changes in simulated precipitation. Precipitation anomalies generally remained within approximately ±2 mm day⁻¹ in February and below ±0.5 mm day⁻¹ in July. These anomalies exhibited fragmented spatial patterns, with no systematic increase in precipitation around the lake or along the prevailing wind direction. Overall, the findings indicate that changes in Lake Jazmurian extent have a negligible influence on regional precipitation under the simulated atmospheric conditions, which remains primarily controlled by large-scale atmospheric circulation and regional topographic conditions.