Evaluating Extreme Precipitation Forecasts In Tarapacá, Chile Region Using Convective-Permitting Modeling

Presenter: Lourdes Mendoza-Fierro1
Co-Author(s): Hsin-I Chang, Rodrigo Valdés-Pineda, Christoforus Bayu Risanto.
Advisor(s): Dr. Christopher Castro
1Department of Hydrology and Atmospheric Sciences, University of Arizona

Panapto Presentation Video
Oral Session 1: Weather and Hydroclimate Extremes

In recent years, the Tarapacá region in northern Chile has experienced extreme precipitation events causing flash flooding, landslides, and associated adverse socioeconomic impacts. These events are likely to worsen in the future due to an increase in precipitation intensity driven by climate change. Recent studies have shown high precipitation forecast skills of convective-permitting models within South America, including areas with complex terrain like Tarapacá, improves simulated precipitation events at regional scales, which can then be used to evaluate hydrologic responses. In this work, the Weather Research and Forecasting (WRF) is used at convective-permitting resolution to design an ensemble-based, real-time forecast system for deterministic weather forecasts in Tarapacá. The Global Ensemble Forecast System (GEFS) is used to specify the lateral boundary conditions, with all 20 ensemble members. The simulation is 120 forecast hours, to provide retrospective precipitation forecast 2 days prior and 2 days after the observed extreme weather event. Preliminary results from retrospective simulations of extreme precipitation events show an improved representation of total precipitation, as compared to the driving global forecast model and satellite observations. A well-known problem in the steep terrain of the Andes is that satellite observations substantially underestimate the precipitation. So, we also explore the possibility to evaluate a modeled streamflow response using convective-permitting model output to drive a hydrologic model, as a possible new evaluative metric.

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