In this study, we analyze land-atmosphere interactions over the La Plata River basin in South America using the Weather Research and Forecast (WRF) model with the added capability of water vapor tracers (WRF-WVT). The La Plata is the second largest basin of South America after the Amazon but far exceeds the Amazon basin in hydroelectric power, agriculture and livestock. A better understanding of land-atmosphere interactions in this region will likely lead to improved predictability of precipitation. We are requesting 78,692 Stampede2 node-hour SUs and 200 TB of Ranch storage to perform high-resolution simulations over the region using control simulation (10 years) and an experiment with modified land surface conditions (10 years). As part of this request we will work with an expert in visualization of these types of data.