Extreme Rainfall Event Observed in Northern of Rio Grande do Sul

Abstract

This paper analyzes atmospheric conditions related to an extreme rainfall event that reached Northern of Rio Grande do Sul (RS) in July 10, 2007. Different data sources were used: rainfall daily data from 16 meteorological surface stations of RS to verify the rainfall registered on RS during the event; infra-red (channel 4) satellite imagery from GOES 10 (Geostationary Operational Environmental Satellite), to analyze the evolution of meteorological system that generated the event; surface and altitude synoptic charts from July 10, 2007 at 00 UTC to analyze the meteorological systems acting on the RS and data from NCEP-CFSR Reanalysis (National Centers for Environmental Prediction -- Climate Forecast System Reanalysis), to analyze the large-scale environment associated with the event. The results showed that the circulation in low-level of the atmosphere contributed to supply the study area with large amount of heat and humidity. This condition combined with the occurrence of Frontal System observed from July 09, 2007 contributed to the organization of atmospheric instability and convective cloudiness observed, favoring the occurrence of the extreme rainfall registered in Northern RS in July 10, 2007.