Evaluation of rainfall and atmospheric parameters during afternoon summer storms over Macaé city (Brazil) using WRF numerical model

Abstract

Forecasting summer storms requires addressing critical atmospheric conditions to determine the potential of their development and further evolution. However, due to the high degree of variability in the development of the storms, their early detection still represents a challenge to the operational forecasters and scientific community. In this context, this study endeavored to evaluate the rainfall and atmospheric parameters simulated by the Weather, Research, and Forecasting (WRF) numerical model using three grid domains (27 km, 09 km, and 03 km). This study proposed an evaluation of precipitation and atmospheric parameters for ten summer storm events over Macaé city during the austral summer of 2020 and 2021, as initially reported by local observers. The synoptic chart data showed that the local effects, the frontal systems passages, and the South Atlantic Convergence Zone (SACZ) were related to the storms observed. From the qualitative evaluation of the precipitation simulated by WRF, we found higher values over the mountainous region of Macaé city and lower values downstream. The quantitative assessment showed that the WRF model could reproduce the hourly rainfall development, although with a tendency of underestimation compared to the observations. The mean temporal evolution of atmospheric variables over Macaé city corroborated the importance of the joint analyses of thermodynamic and dynamic parameters and the increase of horizontal grid resolution to represent better the environment favorable to storm development.