On the night of August 2 and dawn of August 3, 2011, a nocturnal warming was observed at several weather stations in the city of Rio de Janeiro - RJ. This warming occurred suddenly and intensely, with an increase of up to 5°C in one hour at Tom Jobim International Airport (SBGL) and Santos Dumont Airport (SBRJ), and 3.9°C at the Forte de Copacabana weather station. Normally, the diurnal temperature cycle is well characterized, so that the lowest and highest values are observed in the early morning and mid/late afternoon, respectively. However, some meteorological phenomena can cause changes in this cycle, most commonly when a cold front passes through. Through reanalysis and a numerical simulation of the event using the Weather Research and Forecasting (WRF), a regional numerical weather prediction model, characteristics were identified in the atmospheric column, such as a layer of drier air at medium levels, just below a wetter layer, as well as a thermal inversion near the surface. These results are similar to those pointed out by Johnson (1983) for heat burst events, which are characterized by a sudden increase in air temperature simultaneously with a decrease in humidity at the surface. Heat bursts can be associated with the dissipation of storms and are typically nocturnal in nature, when a stable boundary layer develops during this period and plays an important role to its development.
Keywords : Nocturnal heating , Heat burst, Rio de Janeiro.